Device for holding medical instrumentation sensors at and upon the cervix os of a human female, particularly for holding the ultrasonic transducers of an ultrasonic transit time, real-time, cervical effacement and dilatation monitor

A flexible elastomeric annulus-shaped membrane having a shape-retentive memory and exerting a force so as to assume and to maintain a predetermined closed-loop geometric shape, normally a circle, fits circumferentially about the cervix os of a human female so as to hold and retain medical instrumentation probes, preferably two opposed wire-connected ultrasonic transducers of a real-time transit-time ultrasonic monitor of cervical dilatation and effacement. The annular membrane may optionally extend as a tube downwards in the vaginal canal, in the manner of a female diaphragm, as to shield the wires from the walls of the vagina. The membrane expands and contracts with such cyclical variation in the dilatation and effacement of the cervix os as occurs from the earliest onset of labor until imminent childbirth. The membrane holding the transducer probes of an ultrasonic cervimeter may be situated in place about the cervix os for prolonged periods ranging to several months, or may be placed only at the onset of full labor, for monitoring purposes.

The present application is a companion to U.S. patent application Ser. No. 
08/514,234 for a SYSTEM AND METHOD FOR THE INFUSING OF TOCOLYTIC DRUGS IN 
RESPONSE TO THE ONSET OF PREMATURE LABOR DETECTED BY ULTRASONIC MONITORING 
OF THE DILATATION AND/OR EFFACEMENT OF THE CERVIX OS filed on an even date 
herewith. The related application is to inventors including the selfsame 
Michael Harrison, W. Scott Kemper and Michael P. Guberek who are among the 
co-inventors of the present application. 
The contents of the predecessor and of the companion patent applications 
are incorporated herein by reference. 
BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention generally concerns devices for holding medical 
instrumentation probes at an in contact with the cervix os of a human 
female. 
The present invention particularly concerns non-penetrating elastomeric 
devices that hold position at and about the cervix of in order to hold the 
probes of medical instrumentation in position at the cervix even during 
such periodic dilation and effacement thereof as are in advance of the 
onset of, and during, labor, particularly including, but not limited to, 
the ultrasonic transducers of an ultrasonic transit time, real-time, 
cervical effacement and dilatation monitor (being a type of cervimetry and 
cervimeters such as uses ultrasound as a basis of measurement). 
2. Description of the Prior Art 
Although the present invention will be seen to be quite general in 
application for holding medical instrumentation probes at and on the 
cervix os of the human female, one particular, preferred embodiment of the 
invention will seen to be particularly adapted (i) for holding a pair 
ultrasonic transducers, while, and nonetheless to, (ii) any periodic 
dilation (and, alternately cyclically, constriction) and cyclical 
effacement of the cervix os in advance of the onset of labor. This 
particular embodiment is intended for use with the ultrasonic transducers 
of an ultrasonic cervical effacement and dilatation monitor, including a 
monitor that is transit time, real-time, and/or ambulatory. 
The use of such a transducer probe holder, and such a ultrasonic cervical 
monitor, in the present and in the related inventions is directed to the 
avoidance of spontaneous abortion and premature labor, and the 
prolongation of gestation, in human females. Gestation is desirably 
prolonged for variously increasing minimum periods in order to (i) make 
more probable a viable live birth, (ii) reduce the incidence of health 
complications attending a prematurely born child, and (iii) reduce the 
time period during which a premature infant, even if healthy, must, 
because of its size and viability, receive extraordinary care. All the 
factors of (i) live birth, (ii) a healthy child, and (iii) a child that 
can timely leave the hospital in the custody of its parents, obviously 
have an impact on the happiness and well-being of the parents and 
relatives. There is also and impact on society, including a very great 
societal economic impact in caring for children delivered greatly 
prematurely. 
Fortunately, there is a class of drugs call tocolytic, or labor-preventing, 
drugs that are effective to postpone labor if, and only, if administered 
before the full onset thereof. These drugs have undesirable side effects, 
and cannot be continuously administered to a pregnant woman during the 
duration, or even during the high risk period, of a her pregnancy. It is 
necessary to (i) timely detect the early onset of labor, and (ii) timely 
administer a tocolytic drug, if labor is to be avoided, and pregnancy 
prolonged. As will be further discussed, the cyclical dilatation and 
effacement of the cervix os of a gravid female appears, circa 1995, to be 
a useful and non-invasive way of detecting the early onset of labor in 
mammals, including humans. 
The record short human gestations which have resulted in viable live births 
are, circa 1995, twenty-six (26) weeks. These exceptionally rare survivals 
are the subjects of papers in medical journals. The normal period 
considered the practical minimum for gestation if a live birth is likely 
realizable in a major medical center is twenty-eight (28) weeks. If the 
birth transpires in a facility without specialized facilities for the care 
of premature infants, or in areas of the second or third world where 
childbirth becomes progressively more hazardous for both the mother and 
child, the period during which the child is desirably maintained in utero 
increases all the way to normal full term. Human gestation is desirably 
extended to thirty-four (34) weeks in order to assure near-normal 
probability of a viable live birth even under the best, first-world, 
circumstances. Although the probability of successful delivery, and the 
good health of the newborn continues to improve (sometimes for reasons 
more reflective of the overall good health and prenatal care of the mother 
as opposed simply to the benefit of being longer in the womb) all the way 
up to the normal full human gestation period of thirty-six to forty 
(36-40)weeks, active medical intervention is normally not used to postpone 
labor beyond thirty-four (34) weeks. 
Accordingly, human gestation is, if possible and other medical conditions 
of the pregnant woman not counter-indicating, preferably prolonged as long 
as about thirty-four (34) weeks, which is considered the lower limit for 
live birth in advanced modern facilities without appreciably greater 
complications than are incurred by babies carried to the full normal term 
of thirty-six to forty (36-40) weeks. If gestation can be prolonged from 
the practical minimum of twenty-eight (28) weeks at which viable live 
births routinely transpire in advanced hospitals for only four (4) weeks 
longer, i.e., to thirty-two (32) weeks, then a cost savings in excess of 
$100,000 to $300,000 U.S. can typically be realized circa 1995--even over 
the costs of continuous hospitalization and monitoring of the mother 
during the critical period. It should be understood that there are some 
areas of the United States, and most of the world, where neither the 
quality nor the quantity of resource exists to keep a highly premature 
infant alive. Although direct financial outlays may be less in these 
areas, the human cost is very great. People inevitably wishing to have 
children, and there being no viable way to even certainly detect, let 
alone prevent the pregnancies of, females at risk for premature delivery, 
it is thus of consummate interest to prolong, if possible, pregnancies 
until (usually) near full term. 
Cause and constant supervision of high-risk pregnancies has historically 
involved the use of what were, at the times introduced, new and advanced 
technologies. This lengthy background has led, culminating in the present 
and related inventions, to the continuous recording and monitoring of 
cervical dilatation during labor by means of ultrasonic cervimetry. To 
support this continuous monitoring, probes must be maintained continuously 
in position. 
The ancients knew that the dilatation of the cervix, discernable with and 
by the fingers during manual digital assessment, attended the onset of 
labor in the human female. 
2.1 The General History of Cervimeters Including Ultrasonic Cervimeters, 
and of the Measurements Obtainable With Such Cervimeters 
Current medical knowledge of cervical behavior descends largely from a huge 
base of historical data obtained by repeated digital palpation or `digital 
cervimetry` during labor. Both vaginal and rectal examination have been 
used. The latter method was introduced by Kroenig to prevent ascending 
uterine infection. Reference Kroeig, A. . Der Ersatz der inneren 
Untersuchung Kriessender durch die Unteersuchung per Rectum; CENTRALBL 
GYNAKOL 1894; 18:235-243. Semmelweiss' classic work involving the 
relationship between vaginal examination and puerperal infection is well 
appreciated. Reference Semmelweiss, I., in Von Gorky, Y., ed., 
Semmelweisss gesammte Werke, Jena. 1905, VEB Gustav Fisher Verlag. 
Although digital examination offers valuable clinical information on the 
progress of labor, its intermittent character does not allow an assessment 
of the dynamics of cervical dilatation. For that reason many attempts have 
been made to construct devices, cervimeters, for objective and continuous 
measurement of cervical dilatation based on (electro) mechanical, 
electronic and ultrasonic principles. A historical overview of some of 
nineteen various instruments published since the early fifties is 
presented in the article Assessment of cervical dilatation during labor; a 
review, by T. vand Dessel, et al. appearing in EUR. JNL. OBS. GYN. & REP. 
BIO. 41 (1991) 165-171. 
Instrument-based cervimetry, or cervical dilatation measurement, has in 
particular been performed by mechanical, magnetic and/or ultrasonic means. 
A history of instrument-based cervimetry is presented by Moss, P. L., et 
al. as Continuous cervical dilatation monitoring by ultrasonic methods 
during labor, appearing in AM. J. OBSTET. GYNECOL. 132:16, 1978. The 
following text is derived from that article. 
Moss, et al. point out that Friedman was the author in 1936 of a report 
discussing mechanical cervimetry. See Friedman, E. A.: Cervimetry, an 
objective method for study of cervical dilatation in labor, AM. J. OBSTET. 
GYNECOL. 71:1189, 1956. This paper was followed by another paper 
co-authored with Von Micsky in 1963. See Friedman, E. A., and Von Micsky, 
L. I.: Electronic cervimeter, A research instrument for the study of 
cervical dilatation in labor, AM. J. OBSTET. GYNECOL. 87:789. 
Siener cooperated with West from 1962 to 1972, and with Krementsoy in 1968, 
in the use the same method. See Siener, H.: An apparatus for recording the 
opening of the cervix during labor, ZENTALBL GYNAEWKOL 78:2069, 1956; 
Siener, H.: A new electromechanical apparatus for measuring labor 
activities by the execution of combination measurements, ARCH. GYNAEKOL. 
196:365, 1961; Siener, H.: First stage of labor recorded by cervical 
tonometry, AM. J. OBSTET. GYNECOL. 86:303, 1963; Siener, H. and West, I.: 
Internal isometry and graphic registration of cervix dilatation as a basis 
for calculation of labor effectiveness and soft tissue resistance, 
GEBURTSHILFE FRAUENHEILKD 32:123. 1972; and Krementsoy, U.: Improved 
technique for measurement of cervical dilatation, BIOMED. ENG. (N.Y.) 
2:350 1968. 
The magnetic cervimeter was first proposed by Smith in 1954. See Smith, C. 
N.: Measurement of the forces and strains of labor and the action of 
certain oxytocic drugs, International Congress of Obstetrics and 
Gynecology, Geneva, 1954, S. A. George, P. 1030. However there were many 
drawbacks and it was only in 1971 that Rice, and also Kriewall, tried to 
solve these problems. Reference Rice, D. A.: Mechanism and measurement of 
cervical dilatation. Doctoral thesis, Purdue University, Lafayette, 
Indiana, 1974. Reference also Kriewall, T. J.: Measurement and analysis of 
cervical dilatation in human parturition, Doctoral theses, University of 
Michigan, Ann Arbor, Mich. 1974. 
Ultrasonic cervimetry was introduced in the period from 1974 to 1976 by 
Neuman, Wolfson, and Zador. Reference Neuman, M. R. Wolfson, R. N. and 
Zador, I,: Ultrasonic transit time methods for monitoring the progress of 
obstetrical labor, TRANSACTIONS OF PROFESSIONAL GROUP ON 
ULTRASONICS--IEEE, Vol. 33, 1975; Zador, J.: Ultrasonic determination of 
cervical dilatation during labor, Master's thesis, Case Western Reserve 
University, Cleveland, Ohio, 1974; Zador, I, Neuman, M. R. and Wolfson, R. 
N.: Continuous monitoring of cervical dilatation during labour by 
ultrasonic transit-time measurement, MED. BIOL. ENG. 14-229, 1976; and 
Wallenburg, H. C. S., and Wladimiroff, J. W.: Ultrasonic measurement of 
cervical dilatation during labor, AM. J. OBSTET. GYNECOL. 126:288, 1978. 
A comparison of the advantages and inconveniences of each prior art method 
is shown in the first four columns of the Table of FIG. 1. 
2.2 Ultrasonic Cervimetry 
A typical advanced method of ultrasonic cervimetry, and the analysis of the 
measurements obtained thereby, was expounded by Moss, P. L., et al. in the 
aforementioned paper Continuous cervical dilatation monitoring by 
ultrasonic methods during labor, appearing in AM. J. OBSTET. GYNECOL. 
132:16, 1978. 
The major goal of Moss, et al., as stated in their own words, was to 
evaluate ultrasonic cervimetry and to look at the characteristics of the 
recordings with respect to conventional variables of fetal monitoring. In 
particular, Moss, et al. looked at the relationship between dynamic 
changes in cervical dilatation and intrauterine pressure. They looked at 
both the amplitudes of the changes and the phase relationships between the 
two signals. 
The installation of the transducers consisted of fixing two piezoelectric 
crystals, each of dimension 1 mm by 5 mm, to the external os of the 
uterine cervix. The installation took place at 3 cm or more of dilatation. 
The crystals were fixed in places dramatically opposed to each other and 
were so held in position by spring-loaded clips. 
The ultrasonic cervimeter in use generated an ultrasound wave each second, 
and the total time elapsed from the emission of that signal by one crystal 
to the reception by the other was compiled and converted into a distance. 
The ultrasound wave velocity was considered to be constant at 1.48 mm per 
microsecond. Since time, and not intensity, of the signal was the 
important parameter, the crystals had to rotate more than 60 degrees from 
one another before an error in the measurements was introduced. Migration 
was not possible since the clips teeth, when closed, pierced the cervix 
through and through. 
The dilatation value along with the fetal heart rates, the fetal 
electrocardiograms, and the uterine contractions were recorded on an eight 
channel recorder. 
Clinical accuracy was 0.6 cm. When the ultrasound recording of cervical 
dilatation is compared to the intrauterine pressure curve, it is 
characterized by a baseline and wave-shape curve of dilatation (DWP). The 
maximal amplitude component is called cervical maximal plasticity. The 
onset of the DWP is related to cervical resistivity, and the end of DWP 
reflects the relaxation time of cervical dilatation. The data show that as 
dilatation enters the active phase of labor, the plasticity, the 
resistivity, and the duration of relaxation of the cervix increase. These 
observations are related to the structural changes of the cervix during 
labor. (AM. J. OBSTET, GYNECOL. 132.16 1978). 
It was noted by Moss, et al. (op. cit.) that cervical dilatation and fetal 
descent can be monitored simultaneously by ultrasound. 
2.3 Problems With Previous Cervimeters--Mechanical and Electromechanical 
Cervimeters 
The analysis of this section 2.3, and of the following sections 2.4 and 
2.5, is a substantial extract and paraphrase of the aforementioned article 
Assessment of cervical dilatation during labor: a review, by T. van 
Dessel, J. H. M. Frijns, F. Th. J. G. Th. Kok, and H. C. S. Wallenburg 
appearing in EUROPEAN JOURNAL OF OBSTETRICS & GYNECOLOGY AND REPRODUCTIVE 
BIOLOGY, 41 (1991) 165-171. 
Two main prototypes of mechanical cervimeters have been described, the 
calipers-type and the string-type. 
In the basic calipers-type cervimeter, X-cross calipers equipped with a 
centimeter rule at the distal end are used to measure the distance between 
opposing cervical rims. The Krementsov cervimeter, called an 
`orificiometer` 18!, has a ring at each proximal caliper end in which the 
fingers of the examiner can be placed. See Krememtsov, Y. G., Improved 
technique for measurement of cervical dilatation, BIOMED. ENGIN. 
1968:2:350. It enables the examiner to verify his findings by vaginal 
examination. The Tervila cervimeter consists of two pairs of Kelly clamps, 
attached separately to the cervical edges, and connected in a hinge-like 
way. See Tervila, L., Measurement of cervical dilatation in labour, AM. J. 
OBSTET. GYNECOL. 1953;51:374-376. The Friedman cervimeter is equipped with 
bulldog clips for attachment to the cervical rims. See Freidman, E. A., 
Cervimetry: an Objective method for the study of cervical dilatation in 
labor, AM. J. OBSTET. GYNECOL. 1956;71:1189-1193. Measurement is 
continuous, but readings are obtained at 2 to 10 minute intervals and 
plotted manually against time. 
Disadvantages of these simple mechanical cervimeters are the discontinuity 
of readings, the lack of recording facilities and the quite heavy 
mechanical construction that interferes with dilatation during 
measurement. 
In later years, low-weight calipers with cervical attachment clips were 
combined with potentiometers to convert the movements of the caliper arms 
into an electrical signal that could be recorded on a polygraph. 
Electromechanical cervimeters of this basic type were described by 
Vossius, G. in Eine Methode zur guantitativen Messung der Erweiterung und 
des Tiefertretens des Muttermundes Wahrend der Geburt. Z GESAMTE EXP MED 
1961;134:506-512, by Svoboda, M. in CSL. GYNAEKOL 1958;23:621-623, cited 
by Warm R., Ueber die Messung der Muttermundseroffnung unter der Geburt. Z 
Arztl Fortbild 1967;61:661-666, by Richardson, J.Aa, Sutherland, I. A., 
Allen D. W., and Dore F., in The development of an instrument for 
monitoring dilatation of the cervix during labour; BIOMED. ENGIN. 
1976;11:311-313, and by Richardson J. A., Sutherland I. A.; Measurement of 
cervical dilatation during labour; Physical science techniques in 
obstetrics and gynecology, Tunbridge Wells: Pitman Medical, Kent, United 
Kingdom, 1977. In the paper The electromechanical Friedman cervimeter by 
Friedman, E. A., and Von Micsky, L. I., an electronic cervimeter is taught 
as a research instrument for the study of cervical dilatation in labor. 
Reference AM. J. OBSTET. GYNECOL. 1963;87:789-792. The Freidman electronic 
cervimeter is attached to the cervix by a retractable row of needles. At a 
preset dilatation the needle attachments to the cervix are automatically 
released. In another instrument developed and expounded by Langreder, W. 
in Geburtshilfliche Messungen, BIBL. GYNAECOL 1965;20 (S), movements are 
recorded by means of a photoelectric cell. The cervimeters described by 
Warm, R. in Ueber die Messung der Muttermundseroffnung unter der Geburt. 
appearing in Z. ARTZL FORTBILD 1967;61:661-666, and by Kazda S. Brotanek 
V. in Part played by cervix in uterine activity at the onset of labour 
appearing in CSL. GYNAEKOL 1962;27:333-337, have a similar design. A pair 
of calipers is connected to an invisible hinge in a heavy extravaginal 
part containing an internal potentiometer. Kazda and Brotanek report 
successful recordings in 90 patients without presenting data. 
Siener has reported several cervimeters. The original Siener cervimeter was 
reported by Siener H., Ein neues elektromechanisches Wehenmessgerat zur 
Durchfuhrung von Kombinationsmessungen, ARCH. GYNAKOL 1961;196;365-372, by 
Siener H., First stage of labor recorded by cervical tonometry; AM. J. 
OBSTET. GYNECOL. 1963;86:303-309, by Siener H. and Wust L., Innere 
Wehenmessung and graphische Registrierung der Muttermunds-Eroffnung als 
Grundlagen zur Berechnung der Weheneffektivitat und des 
Weichteil-widerstandes; GEBURTSH FRAUENHEILK 1972;32:125-130. It was also 
reported by Embrey M. P. and Siener, H. Cervical tocodynamometry; J. 
OBSTET. GYNAECOL. BRIT. COMMONW. 1965;72:225-228, and in Siener H., 
Cervical dynamometry, a new method in obstetrical research; Am. J. OBSTET. 
GYNECOL. 1964;89:579-582. The Siener cervimeter offers the opportunity for 
both measurement of cervical dilatation and measurement of cervical 
dilatation forces, after fixation of the calipers. Later Siener used the 
concept of the electromechanical calipers cervimeter to construct even 
more sophisticated devices: the cervical dynamometer and the `erweiterte 
Zervixwehenmesser` (`expanded cervix-contraction meter`). Reference Siener 
H., Die erweiterte Zervixwehenmessung; GEBURTSH FRAUENHEILK 
1959;19:140-145. The cervical dynamometer allowed measurement of the 
pressure of the fetal head on the cervix after fixation of the 
intravaginal arms of the cervimeter. The `expanded cervix-contraction 
meter` combined a calipers cervimeter with a metal construction for 
measurement of fetal descent. 
The string-type cervimeter consists of strings or cords, attached to the 
cervix. Changes in dilatation cause changes in length of the strings which 
are transmitted to a kymograph by a mechanical pulley-guided system. 
Reference Siener H., Studien uber das Verhalten des Muttermundes wahrend 
der Eroffnungsperiode; ARCH. GYNAEKOL 1957;118:556-576. Alternatively, the 
changes could be electrically communicated by a linear differential 
transformer. Reference Smyth C. N., Measurement of the forces and strains 
of labour and the action of certain oxytocic drugs. Comptes Rendus du 
Congres International de Gynecologie et d'Obstetrique, Geneva, 
1954;1030-1039. 
Some instruments are described for assessment of cervical properties other 
than dilatation. Glass and coworkers has used the medical engineering 
principle of indentation to design an electromechanical device for 
measurement of the relative softness of the cervix. Reference Glass B. L., 
Munger R. E., Johnson W. L.; Instrument to measure tissue softness of the 
uterine cervix in pregnancy; MED. RES. ENGIN. 1968;7:34-35. An instrument 
to measure the amount of pressure of the fetal head on the cervix has been 
reported by Noack and Blaschkowski. Reference Noack H. and Blaschkowski 
E., Zur Frage der graphischen Registrierung von Kontraktionen des 
Muttermundes unter der Geburt; Z. GYNAKOL 1958;80:160=-1616. 
Mechanical cervimeters are cumbersome in clinical practice and they cannot 
be used for continuous measurement of dilatation. Most electromechanical 
devices offer the possibility of continuous registration but have the 
disadvantage of a mechanical intravaginal part, which may interfere with 
cervical dilatation. 
2.4 Problems With Previous Cervimeters--Electromagnetic Cervimeters 
Electromagnetic cervimeters were described by Wolf in a his congress 
report: Wolf W., Kongressbericht. ARCH. GYNAKOLOGIE 1951;180:177-180; and 
later by Rice, D. A. in Mechanism and measurement of cervical dilatation; 
Doctoral dissertation. 1974, Purdue University, Lafayette, Ind. U.S.A. 
With these cervimeters cervical dilatation is measured using two small 
induction coils, attached to opposing cervical rims. An electrical 
current, sent through one of the coils, establishes a magnetic field that 
is detected in the opposite coil and then recorded. Kriewall has used a 
permanent magnet dipole as a magnetic field source and two Hall-effect 
magnetic-field transducers as detectors. Reference Kriewall, T. J., 
Measurement and analysis of cervical dilatation in human parturition; 
Doctoral thesis, 1974, University of Michigan, Ann Arbor, Mich., U.S.A. 
The signals derived with this technique are processed to determine the 
distance between the transducers. 
Electromagnetic cervimeters with clinical applicability have not been 
described. 
2.5 Problems With Previous Cervimeters--Ultrasound Cervimeters 
Abdominal routes have been used to visualize cervical dilatation by means 
of ultrasound during pregnancy. Reference Sarti D. A., et al. Ultrasonic 
visualization of a dilated cervix during pregnancy; RADIOL. 
1979;130:417-420; Varma T. R., Patel R. H., and Pillai U. Ultrasonic 
assessment of cervix in normal pregnancy; ACTA. OBSTET. GYNECOL. SCAND. 
1986;65:229-233; Parulekar S. G. and Kiwi R., Dynamic incompetent cervix 
uteri; J. ULTRASOUND MED. 1988;7:481-485. 
Vaginal routes have been used to visualize cervical dilatation by means of 
ultrasound during pregnancy. Reference Balde M. D., Stolz W., Unteregger 
B., and Bastert G.; L'echographie transvaginale, un rapport dans le 
diagnotic de la beance du cal uterin; J. GYNECOL. OBSTET. BIOL. REPROD. 
(Paris) 1988;17:629-633 
Transperineal routes have been used to visualize cervical dilatation by 
means of ultrasound during pregnancy. Reference Lewin B., 
L'echotomographie perineale. Une nouvelle methode de mesure objective du 
cal; J. GYNECOL. OBSTET. REPROD. 1976;5:289-295; and Jeanty P., Perineal 
scanning; AM. J. PERINATOL. 1986;3:289-295 
Reports in the literature dealing with systematic visual assessment of 
cervical dilatation during labor could not be found by T. van Dessel, et 
al. (op. cit.), nor by Applicants. 
A different approach uses two ultrasound transducers attached to opposing 
rims of the cervix. An ultrasonic signal generated by one transducer is 
received by the opposing one. Since the ultrasound velocity is known, the 
transmission time allows computation of the distance between the 
transducers. 
The first ultrasound cervimeter was described by Zador et al. in 1974. 
Reference Zador, I, Neuman, M. R., and Wolfson, R. N.; Continuous 
monitoring of cervical dilatation during labour by ultrasonic 
transmit-time measurement; MED. BIOL. ENGIN. 1976;14:299-305; also Zador, 
I, Wolfson R. N., and Neuman, M. R., Ultrasonic measurement of cervical 
dilatation during labor; ANN. CONF. ENGIN. MED. BIOL. 1974;16:187. These 
authors used spring-loaded clips to attach the transducers to the cervix. 
A total of 24 readings of women in labor were reported, but no specific 
data were given. Apparently, practical problems were encountered, because 
further clinical studies with this device could not be found. 
A similar cervimeter has been presented by Kok et al. in 1976 in 
preliminary reports. Reference Kok, F. T., Wallenburg, H. C., and 
Wladimiroff, J. W., Ultrasonic measurement of cervical dilatation during 
labor; AM. J. OBSTET. GYNECOL. 1976;126:288-290; also Eijskoot, F., Storm, 
J., Kok, F. T., Wallenburg, H., and Wladimiroff, J.; An ultrasonic device 
for continuous measurement of cervical dilatation during labor; 
ULTRASONICS 1977;55:183-185. The problems with the fixation of the 
transducers to the cervix were eliminated by using special spiral-shaped 
transducers. The data was analyzed off-line by a computer, and accuracy 
and precision in vitro and in vivo were shown to be good in a 
well-documented study of 62 women in labor. Reference Kok, FTJGT; 
Ultrasonic cervimetry (summary in English); PhD-Thesis, Erasmus 
University, School of Medicine and Health Sciences, Rotterdam, 1977. 
Cervical dilatation appeared to follow a wave pattern reflecting the 
intrauterine pressure curve. Maximal cervical dilatation coincided with 
the maximal intensity of each contraction. Generally, the derived curve of 
cervical dilatation showed the sigmoid shape postulated by Friedman (op. 
cit.) and by Krementsov Y. G. in Improved technique for measurement of 
cervical dilatation; BIOMED. ENGIN. 1968;2:350. A decelerative phrase was 
never detected. Using a similar device Moss and coworkers have 
investigated 13 women in labor. Reference Moss P. L., Lauron P., Roux J. 
F., Neuman M. R., and Dmytrus K. C.; Continuous cervical dilatation 
monitoring by ultrasonic methods during labor; AM. J. OBSTET. GYNECOL. 
1978;132:16-19. T. Van Dessel, et al. (op. cit.) observed--contrary to the 
findings reported by Kok, Zador I, Neuman M. R., Wolfson R. N. in 
Continuous monitoring of cervical dilatation during labour by ultrasonic 
transmit-time measurement. MED. BIOL. ENGIN. 1976;14:299-305--that the 
peaks of uterine contraction and cervical dilatation were out of phase. 
Ultrasound visualization of the cervix may be helpful in monitoring the 
patient at risk for premature delivery, but does not allow continuous 
registration of dilatation during labor. However, ultrasonic cervimetry 
does offer continuous and reliable recording with little discomfort to the 
patient, but clinical data has been limited. T. van Dessel, et al., (op. 
cit.) felt in 1991 that "u! ltrasound cervimetry may be a useful research 
tool for the study of the cervical response to the uterine contractions 
during labor. For clinical obstetric purposes, however, digital assessment 
of cervical dilatation seems sufficient." 
2.6 Problems With Previous Ultrasonic Cervimeters--Position-holding of 
Placed Probes 
In the predecessor patent application it is taught that ultrasonic 
transducers to which various barbs of the order of corkscrews to fish 
hooks are affixed may be reliably semi-permanently affixed to the cervix 
os, which is devoid of nerve endings. The fact that the placement of these 
vicious-looking devices may benefit the patient without inducing pain or 
harm--much in the manner of the similarly-appearing corkscrew probe of a 
cardiac pacemaker--does little to assuage the sensitivities of the female 
in whose birth canal these devices are to be affixed. 
Especially since the ultrasonic probes are generally to be maintained in 
position for a prolonged period ranging to many months while the carrier 
female is conscious, and because the carrier female must be able to 
recognize a probe should it come loose and become resident in, or become 
ejected from the vaginal canal, the patient should be shown the probe and 
its affixation means, and its function and operation should be explained 
to the patient, and should be understood by the patient. 
The present invention will be seen to be directed to a more 
psychologically-user-friendly placement and holder device for cervical 
instrumentation, including a pair of ultrasonic transducer probes as may 
be used with a cervical dilatation and effacement monitor. 
2.7 The Desirability of Continuous Accurate Convenient Cervical 
Dilation/effacement Monitoring, With Automated Alarms 
The inventors of the present invention are of a contrary opinion to the 
opinion of T. van Dessel, et al., (op. cit.) in the aforementioned paper 
that "digital assessment of cervical dilatation . . . is! sufficient" and 
that, by implication, ultrasound cervimetry has no role in the clinical 
environment. 
In the first place, the only realistic alternative to ultrasonic cervimetry 
is, and has proven to be, no cervimetry at all, and exclusive reliance the 
time-honored approach of digital assessment of cervical dilatation. This 
procedure, which should be, and regularly is, performed every hour after 
the onset of labor, is (i) manifestly inadequate to detect the onset of 
labor itself, (ii) laborious, (iii) without automatic contemporaneous 
generation of a permanent record, and (iv) of no greater quality in 
results obtained than the skill and attentiveness of the practitioner. 
Despite the lack of clinical, or patient portable, instrumentation for the 
detection of the onset of labor (should such event be sharply definable, 
and it is), the detection of this event is very important in those rare 
cases where premature labor must be avoided. The inventors of the present 
invention are involved in the verification of instrument with one of the 
major centers for the management of problem pregnancies and premature 
births in the United States if not also the world circa 1994. Prolongation 
of gestation beyond a certain, threshold, number of weeks is currently 
very, even crucially, important to the survival of the fetus at birth. 
This minimum gestation period for live birth has greatly decreased in 
recent years, but cannot be expected to decrease to shorter than the 
period within which spontaneous abortions, or premature labor, occur in 
the human female. Accordingly, the only way that some fetuses will 
ultimately be viable is if tenure in the womb is prolonged. 
Powerful drugs exist to arrest labor. However, these drugs cannot be 
continuously, or even regularly administered, during the projected 
terminal phase (at whatsoever period gestation) of a particular problem 
pregnancy. Accordingly, it is of crucial importance to detect the onset of 
labor (should such event be detectable, and it is) at the earliest 
possible moment in order that it may be stopped, if desired or required, 
by the administration of drugs or otherwise. 
Next, once labor has begun, and even in normal pregnancies and deliveries, 
the inventors of the present invention do not take such a cavalier 
attitude as do their peers to the present lack of hard, recorded, and/or 
instantaneous quantitative data about what has gone on, and is going on, 
from moment to moment during labor. The dilatation/effacement of the 
cervix is a very good indicator of the progress, and or of problems, with 
labor. 
2.7.1 Timing of Therapeutic Regimens Based in Cervical Dilation/Effacement 
Monitoring 
The first, and potentially greatest, advantage to the continuous monitoring 
of cervical dilatation/effacement during labor, if not also in the period 
before, is that it can promote superior timing in the administration of 
medical therapies to support the suppression of labor or during labor. 
Cervical dilatation/effacement monitoring promotes the timely and 
optimally timed therapeutic administrations in consideration of (i) the 
earliest possibly recognition of changing conditions, including problem 
conditions, during labor, (ii) a definitive record of exactly how long 
certain conditions have persisted, and (iii) the possibility of machine 
aids, ranging from alarms to the comparison of profiles to mathematical 
modeling. 
In short, the fact that most births occur normally even should the midwife 
or obstetrician be ignorant of cervical dilatation, and the complementary 
fact that some births encounter problems, are both facts of nature, and 
not of man. However, the fact that intervention in the birth process, 
primarily by Caesarian section, is occasionally ancient and generally 
successful does not invariably mean that it has been optimally timed for 
the health of the fetus and/or the mother. 
Timing in the administration of therapeutic regimens during labor has 
always been recognized to be an issue. For example, the administration of 
pain-killing drugs to the mother is permissible during the early stages of 
labor whereas the administration of the same drugs becomes impermissible 
in later stages of labor. For example, a Caesarian delivery is not 
normally attempted until some lapse of reasonable progress towards a 
normal, vaginal, delivery. The questions that should be asked by a 
clinical practitioner in considering the efficacy of a monitor device in 
accordance with the present invention are these: Is there any evidence 
that the timing of some (or any) interventions is more critical than the 
timing of other interventions, or more critical than is generally 
recognized, or, God forbid, more critical that is generally possible under 
current methods for the measurement of the progress of labor? If so, what 
interventions would so benefit? Finally, is the monitoring of cervical 
dilatation and/or effacement (the thinning of the cervical rim, which 
thinning is of course proportional to the expansion of the cervix) an 
appropriate, or useful, measure of the progress, and/or the onset of 
problems, during labor? The present specification does not contain proof 
that the answers to the first and the third questions are yes, nor need it 
do so. However, such data from clinical trials as is still under 
development circa April, 1994, suggests that this "yes" answer. 
The present invention does not concern the medical diagnosis of problems 
during delivery, which is part of the evolving medical art of obstetrics. 
The present invention does concern, however, new machines and methods for 
the comprehensive measurement and display of, and the generation of alarms 
from, cervical dilatation/effacement during labor. 
2.7.2 The Communication of the History of a Birth Based in Cervical 
Dilation/Effacement Monitoring 
The oral record and the written does not suffice for the communication of 
the stages, and circumstances, of complicated labor. The hard-copy, 
graphical, record of a continuous monitoring of cervical 
dilatation/effacement during labor can promote a number of ends. It 
permits the ready visualization of the progress of the labor. It permits 
all temporal junctures at which therapies were administered to be 
identified, and the results of these therapies (insofar as affecting 
cervical dilatation/effacement) recognized. It permits the ready 
communication of a history of the labor to (i) students, (ii) history, 
(iii) medical review boards and courts, and (iv) other physicians, 
including those who may attend other labors of the same female some years 
hence. 
2.7.3 Diligence in Childbirth Monitoring Based in the Monitoring of 
Cervical Dilation/Effacement 
Childbirth in humans is a lengthy process which can commence totally 
asynchronously with the other duties and schedule of an attending 
obstetrician or midwife. The attentiveness of personnel attending to the 
labor can sometimes languish over the long periods involved. It is equally 
as undesirable that these personnel should be overly zealous. It is (i) 
difficult, (ii) unreasonable on the basis of medical results obtained, 
(iii) and more disturbing than beneficial to the patient, that a physician 
or attending midwife should be making excessively frequent manual digital 
assessment of the dilatation of the cervix during labor. 
Accordingly, manual assessment of cervical dilatation during labor that is 
either too infrequent, or too frequent, is avoided. However, there is a 
fair amount going on in the cervical dilatation on a time scale that is 
short, and thus insufficiently captured, relative to even the most 
frequent manual digital assessment. Namely, this dilatation is cyclic on a 
time scale of typically from one (1) to two (2) minutes, as will be shown 
in this specification. Moreover, there is no desire to delay the 
recognition of changes, especially such changes as may be significant, 
simply because they do not coincide with the periodic, and likely 
infrequent, schedule of manual digital assessment. 
In most labors and deliveries, including those that have problems, 
observational vagaries as may result in (i) imprecision and/or (ii) 
untimeliness in detection/measurement of the dilatation/effacement of the 
cervix the are of no consequence. The challenge is with those few 
difficult, often premature, labors and deliveries in which the timeliness 
and quality of information may be, or become, critical. In episodes of 
labor of this sort the physician faces a dilemma. His continuing 
observational interventions may precipitate the very events that he/she 
seeks to avoid. Conversely, optimal intervention may be compromised if the 
physician is not in possession of the most timely and accurate 
information. 
Accordingly, a system that would continuously, accurately and reliably 
monitor cervical dilatation/effacement during labor without substantial 
discomfort, inconvenience, disturbance or hazard to the patient would be 
very desirable. The present invention concerns such a system. 
SUMMARY OF THE INVENTION 
The present invention contemplates a flexible annulus-shaped membrane 
having a shape-retentive memory and exerting a force so as to assume and 
to maintain a predetermined closed-loop geometric shape, normally a 
circle, circumferentially about the cervix os of a human female. In this 
position the membrane holds and retains one or more medical 
instrumentation probes, preferably two opposed wire-connected ultrasonic 
transducers of a real-time transit-time ultrasonic monitor of cervical 
dilatation and effacement. 
The annular membrane may particularly be made from elastomeric material, 
preferably surgical latex. Both the exterior and interior circular 
circumferential regions of the annulus are preferably somewhat thickened, 
and in the form of an integral rings having a shape-retentive memory. 
However, whereas the exterior ring is substantially stable, exerting a 
continuous pressure force to assume and retain its base dimension and 
circular shape over an indefinitely long period, the interior ring will 
assume over time, at body temperature, and upon expansion of the cervix os 
a slight "set", and will stretch if required to ever larger dimensions. In 
this manner the annular membrane will not only cycle about the instant 
base dimension of the cervix os--should it be called upon to do so--but 
will never become so restrictive so as to, for example, hold closed the 
cervix in the manner of a pessary. The preferred annular membrane is never 
"tight", but is always snug, to the cervix os. 
In one embodiment, the annular membrane preferably incorporates one or 
more, and typically two opposed, cavities at the (preferably thickened) 
rim of its smaller, central, circular opening, in which cavities are 
received and retained medical probes such as, for example, an electronic 
thermal sensor or, more preferably, two ultrasonic transducers. Because 
the preferable two ultrasonic transducers as are held in complimentary 
opposed cavities are held pointed towards each other across the cervix os 
(when the annular membrane is properly inserted), these ultrasonic 
transducers need not be so omnidirectional as was the case with previous 
positional affixation of these probes such as by, for example, screwed 
attachment to the muscle of the cervix os. In other embodiments of the 
annular membrane, the ultrasonic transducers are simply glued to the 
membrane, which is substantially planar. 
The annular membrane comes in a first embodiment that is similar in form to 
a female diaphragm in that the membrane (and it supported instrumentation 
probe(s)) is held in contact with, and about, the cervix os by action of 
being wedged at the top of the vaginal canal. In another, second, 
embodiment, the annular membrane is similar in form to a cervical cap, and 
compressively embraces the cervix os so as to held in position thereupon. 
Finally, in still another, third, embodiment, the annular membrane is 
similar in form to a female contraceptive diaphragm, and is lodged in the 
vaginal canal so high so as to be in contact with the cervix os. In this 
third embodiment a sheath, or large tube, extends downward from the 
exterior circumference of an annular ring lodged in the top of the vaginal 
canal. This tube shields the wire(s) connecting to the probe(s) from the 
walls of the vagina. Other of the embodiments may also incorporate wire 
shields of greater or lessor length, sometimes centrally positioned within 
the vagina so that wires from probes positioned at the cervix os 
essentially extend straight downwards and out the vagina. 
In a variant to any of the embodiments which variant is especially useful 
if (i) instrumentation probes are to be mounted lower in the vaginal 
canal, and/or (ii) surgery is to transpire in or through the vaginal 
canal, the annular membrane may further incorporate within its annulus one 
or more integral small wire conduits, or channels. Two wires--typically 
connecting to typically two ultrasonic transducers that are typically 
mounted at the inner rim of the annulus--are routed to the exterior 
circumference of the annulus, preferably at the same point, and are then 
directed downwards into the vaginal canal, by these conduits. If the 
annular membrane is optionally extended into the vaginal canal, then the 
conduits, or channels, preferably appear only in that portion of the 
flexible annular membrane that is mounted at and about the cervix os. This 
is in order to avoid that any lower-extending small conduit should serve 
as a pathway for bacteria from the vagina to the region of the cervix. 
All these various embodiments and variants with their differing geometries 
have a purpose: each may be variously useful for positioning and holding 
one or more probes in some particular position(s) in the vaginal canal, 
particularly at and across the cervix os, as will later be more fully 
taught. 
The wires and the preferred ultrasonic transducers are coated with a 
biologically inert material, preferably respectively Teflon.RTM. polymeric 
material Teflon is a registered trademark of E. I. DuPont de Nemours) and 
EPO-TEK.TM. coating (epo-tek is a trademark of Epoxy Technology, Inc.). 
The surgical latex is also biologically inert. 
The elastomeric membrane expands and contracts with such cyclical variation 
in the dilatation and effacement of the cervix os as occurs from the 
earliest onset of labor until imminent childbirth, and does not interfere 
with either this natural function nor, if inadvertently not timely removed 
before delivery, childbirth. In the rare situation that the annular 
membrane and its retained probe(s) are still within the vaginal canal upon 
the occurrence of childbirth, the annular membrane and retained probe(s) 
will be pushed from off its seat on and about the cervix os by the 
continuing effacement of the cervical wall, and the entire assembly will 
simply comprise a relatively small and benign item which will be swept, if 
not earlier pulled, from the birth canal during childbirth. 
The annular membrane holding the preferred transducer probes of an 
ultrasonic cervimeter may safely be situated in place about the cervix os 
for prolonged periods ranging to a month. Both the annular membrane and 
its held probe(s) are intended to be (i) entirely disposable, and (ii) 
changeable by the patient woman herself in the manner of a contraceptive 
diaphragm or cervical cap. In the rare case the that the medical probe(s) 
retained by the annular membrane is (are) so expensive that neither 
disposal nor later reclamation of the used probe is practical, it is 
relatively straightforward and non-hazardous to (i) extract the membrane 
and probe(s), (ii) detach the probe(s) from the membrane, (iii) discard 
the used membrane, (iv) wash and sterilize the probes with a chemical 
solution, normally alcohol, (v) insert the cleaned probe(s) in a new 
sterile membrane, and (vi) insert the membrane and its held probe(s) back 
into position at and about the cervix os. Although the wire end(s) of the 
probe(s) are preferably plug connected to the biomedical instrumentation, 
or monitor--and are thus easily unplugged and plugged--it is possible and 
non-hazardous to do the replacement while the probe(s) is (are) still 
connected to a still-energized instrument or monitor. 
The preferred annular membranes and their held probe(s) are self-aligning 
and self-centering in position about the cervix os, and a quality 
replacement may normally be accomplished by an expectant woman herself as 
well as by her gynecologist or obstetrician. In the event of improper 
replacement of an annular membrane carrying the preferred ultrasonic 
transducer probes, the monitor will so indicate by alarming after a period 
of time that, no or an unreasonable cervical dimension being indicated, 
the probes are not detectable to be in reasonable and proper positions. 
Conversely, a good status indication at the cervical dilatation/effacement 
monitor provides a very high degree of assurance to the woman patient that 
she has accomplished the replacement satisfactorily. It should be 
understood that ultrasound cannot be communicated between probe 
transducers save though such intervening tissue and mucous as is normally 
found at the cervix os, and that an ultrasonic distance measurement will 
not transpire between the two ultrasonic transducer probes of a membrane 
that is merely inserted, for example, into the vaginal canal. 
The membrane and its preferred attached ultrasonic transducer probes may 
alternatively be emplaced only at the onset of labor, and for the purpose 
of monitoring the progress of labor. The expectant mother need never have 
previously worn an ultrasonic monitor of cervical dilatation and 
effacement. The automated electronic cervical dilatation and effacement 
monitoring is continuous and accurate, and less obtrusive than periodic 
digital assessment, throughout the progress of labor. Moreover, the latex 
annular membrane itself is less mentally disconcerting, and likely more 
familiar in form, to a woman entering labor--who may already somewhat 
apprehensive--than are the alternative probe affixation 
means--particularly including corkscrews of considerably daunting 
appearance. 
These and other aspects and attributes of the present invention will become 
increasingly clear upon reference to the following drawings and 
accompanying specification.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention is directed to the holding of medical instrumentation 
probes at and about the cervix os of a human female. The present invention 
is particularly directed to holding ultrasonic transducer probes in 
positions about the cervix os of a pregnant human female for purposes of 
measuring and of monitoring the dilatation--meaning opening--or, 
equivalently, the effacement--meaning the thickness of the rim--of the 
cervix uteri, as attends all stages of labor. It should be noted that as 
the cervix expands during labor, increasing the dilatation distance, the 
rim of the cervix stretches and becomes thinner, decreasing the effacement 
distance, or thickness of the rim. One phenomena is related to the other. 
Both phenomena show the same cyclical variation during labor, and each may 
be correlated to the other. 
The probes of an ultrasonic acoustic cervimeter with which the holding 
device of the present invention is beneficially used are preferably 
affixed across the major chord, or diameter, of the cervix uteri from a 
one side to the other, or at least across a minor chord for such a maximum 
distance of separation on the face of the cervix as is possible. In such 
positions the probes measure dilatation. 
However, the probes may be affixed, if required or desired, along but a 
single radii of the cervix with a one probe located more centrally, on an 
interior wall of the cervix (which is in the overall shape of a torus) and 
with the remaining probe located nearby on the exterior wall of the 
cervix. In such a position the probes measure effacement. 
An cervimeter instrument usable with the holding device of the present 
invention may be implemented in many different forms--ranging from a 
straightforward ultrasonic acoustic distance measuring device, or sonic 
cervimeter, to a full-blown computerized cervical dilatation/effacement 
alarming monitor with a memory and a time-based display of a running 
history of dilatation/effacement measurements. One preferred embodiment of 
a cervimeter is as a battery-powered monitor with a memory and a graphical 
display, plus combined audible and visual alarm indications, that is 
completely self-contained and portable, and that is intended for 
continuous use on, partially within, and by, an ambulatory female patient. 
This embodiment typically takes one hundred (100) measurements a second, 
forming a running average of the cumulative measurements taken over a 
period of five (5) seconds and displaying the averaged measurements for 
the previous one hundred and twenty-eight (128) five-second intervals (for 
a total of 102/3 minutes). The cumulative measurements for a longer period 
are stored to the capacity of memory, typically the averaged measurements 
for at least the previous six hundred and forty (640) five-second 
intervals for a total of over sixty (60) minutes. The ambulatory monitor 
typically so functions on two (2) 9 v.d.c. dry cell batteries, typically 
for a period of more than eight weeks. 
A table comparing the major advantages and inconveniences of prior art 
methods of cervimetry with such a method, and instrument, of the present 
invention is shown in FIG. 1. It may immediately be observed that the 
preferred ultrasonic cervimetry method serves, nonetheless to being 
performed by an instrument that is uniquely compact and suitable for 
ambulatory use, to record a history of cervical dilatation/effacement that 
is described as "total" as opposed to "limited". By this it is meant that 
previous monitors, especially including ultrasound monitors, recorded a 
history of cervical dilatation/effacement only when the patient was 
"hooked up" to the previous monitors, usually in a hospital after the 
onset of labor. Data regarding any such long or short term transient 
events during pregnancy as did not lead to the full onset of labor was 
unrecorded and unavailable. Indeed, very little is known at the present 
time about exactly what (other than the lapse of time, or 
intentionally-administered medications) will most likely induce the onset 
of labor in a particular human female, and what precursors to this event 
and/or flags to the likely causative agent(s) (such as exercise, or diet, 
or temperature) might be observed. The cervical monitor for which 
ultrasonic transducer probes are held in position by the device of the 
present invention is, of course, dedicated to providing a full and 
complete record of cervical dilatation/effacement over a period 
potentially as long as many months. During this period of time there is 
little or nothing regarding the dilatation (or, equivalently, the 
effacement) of the cervix that will not be recorded, and archived into a 
history store that is retrievable to and analyzable by, a health care 
professional. Accordingly, the recorded history is described as "total". 
Because the cervical monitor for which ultrasonic transducer probes are 
held in position by the device f the present invention is intended to be 
in continuous use twenty-four hours a day during all periods--which 
periods may be protracted and many months in duration--when the dilatation 
(or, equivalently, the effacement) of the cervix of the female patient 
wearing the monitor is of medical interest, it is possible for the monitor 
to make a visual or audible alarm when certain conditions are detected. 
Certain basic conditions regarding the cervical dilatation/effacement 
curing the onset of, and during the progress of, labor are well 
understood, and the monitor looks for, and alarms, the occurrence of these 
conditions. 
It may well be, and is expected, however, that certain high-risk 
pregnancies will exhibit detectable, possibly unique, phenomena prior to 
events such as spontaneous abortion. If particular warning signs to the 
continuation of the pregnancy of a particular human female, or class of 
human females, can be recognized from the study of historical data on such 
female, or on such class of females, then it is contemplated that it will 
be desirable to warn such a female or females of the incipient occurrences 
of such signs in her/their later pregnancies. As will be seen, the 
ambulatory cervical monitor of the present invention is a programmable 
device. If necessary or desired, it can be preset to alarm, and to 
variously alarm, conditionally upon the occurrence of almost any 
condition(s) of the cervix transpiring over almost any time interval(s) 
that the monitor is capable of detecting. 
Although setting up the ambulatory cervical monitor to alarm upon 
arbitrarily determined criteria (one, or many) involves (as of the present 
degree of understanding of cervical dilatation/effacement indications in 
high-risk pregnancies) highly skilled labor and attendant expense, it 
should be understood that the monitor is intended to be used, among other 
applications, on pregnant females that have never successfully carried so 
long so as to give live birth, let alone to term. Moreover, it should be 
understood that if cautions performed by the female and/or her medical 
advisors in response to monitor alarms and/or recorded records can 
prevent, or can even slightly delay by a matter of months or even scant 
weeks, highly premature births, then the very considerable expense of 
administering to premature newborns can be ameliorated, or even 
substantially saved. 
This simple concept deserves further exposition. People do not like to, and 
effectively cannot, be told that they cannot have children because they 
are at risk of giving birth prematurely, and at great expense. People, 
especially those who desire but do not yet have children, do not like to 
think that such medical care, no matter how expensive, as might permit 
their prematurely born child to survive is being withheld on economic 
grounds. An ounce of prevention is worth a pound of cure--although it is 
perhaps not so "showy" in terms of hospital obstetrics facility, practice, 
and practitioners. A successful obstetrician in the current U.S. health 
care environment (circa 1994) is one who judiciously avoids problems, not 
just one who is skilled in overcoming problems. The cervical monitor with 
which the probe holder of the present invention is preferably used is 
directed to aiding an obstetrician, a general health care practitioner, 
and a woman patient herself, in avoiding the expense, risk, and 
potentially traumatic consequences of premature birth. 
A diagrammatic perspective view of a preferred embodiment of an ambulatory 
cervical effacement/dilatation monitor 1 having disposable probes 13 in 
use for monitoring a pregnant human female 2 (shown partially in cut-away 
view and partially in phantom line) is shown in FIG. 2. The female 2 is 
ambulatory. Wires 12 connect a portable control unit 11 to the probes 13, 
The wires 12 descend (in the standing female) from the cervix os 21 
whereat the probes 13 are affixed through the vagina (not shown) to the 
exterior of the body of the female 2. They then proceed past normal 
boundaries and apertures of both underclothing and clothing to the site of 
the control unit 11, which may be worn virtually anywhere on the body in a 
position covered or uncovered by clothing as is desired. The wires 12 are 
normally quite small and flexible, and are appropriately sheathed in soft 
and flexible plastic. The preferred surrounding plastic is preferably (i) 
surgical grade, (ii) antibacterial, (iii) and readily cleansed. The wires 
and probe bodies are preferably coated with epo-tek.TM. coating available 
from Epoxy Technology, Inc., 14 Fortuna Drive, Dillerica, Mass. 01821 
U.S.A. (epo-tek is a trademark of Epoxy Technology, Inc.). 
The entire interconnection system of the wires 12 is designed with due 
consideration to (i) comfort for long term wear, and (ii) avoidance of 
establishing any path by which germs might abnormally be conducted to the 
region of surface of the cervix 21. 
A detail diagram of the affixation of the disposable probes 13 of the 
ambulatory cervical effacement/dilatation monitor 1 to the cervix uteri 21 
of the pregnant human female 2 (previously seen in FIG. 1) is shown in 
FIG. 3. The particular affixation of the probes 13 that is illustrated is 
where each of the two probes is on the rim of the cervix 21 at roughly 
180.degree. separation. In this position the probes 13 are positioned to 
measure, by the delay in an ultrasound pulse traveling between them, the 
cervical dilatation, or distance across the cervix. Note that in the FIG. 
3 it appears as if the central opening of the cervix os is void and filled 
with air, which would be unsuitable to transmit ultrasound. In actual fact 
the complete path in a substantially straight line between probes 13 is 
completely filled with tissues, mucous and fluids. An ultrasonic path can 
be reliably established and maintained between the probes 13 under all 
normal and abnormal conditions. Indeed, neither ultrasonic signal 
attenuation nor change in attenuation (signal level) presents any 
significant problem(s) or challenge(s)--at least when the preferred probes 
are used (as will be discussed in conjunction with FIG. 4)--and there is 
little difficulty that (i) and ultrasonic pulse emitted at a one of the 
probes 13 will be duly received and the other one of the probes 13, and 
that (ii) this pulse will travel a true path, meaning straight between the 
two probes 13. 
A diagram, at an enlarged scale from FIG. 3b, of one mode of affixation of 
disposable probes to the cervix uteri of the pregnant human female in 
positions to monitor effacement is shown in FIG. 3b. The probes 13 are 
mounted along a same wall region, and normally on opposite sides of the 
wall, of the cervix os 21. When the cervix os 21 dilates (enlarges) then 
the distance between the probes 13 as such are attached in FIG. 3a will 
increase. However, during the same dilatation (enlargement) the distance 
between the probes 13 as such are attached in FIG. 3b will decrease. The 
increase is related (although not linearly) to the decrease, and vice 
versa. The status of the cervix os may be monitored, and interpreted, from 
data concerning either dilatation or effacement (or both). The normally 
measured, observed, monitored and interpreted quantity is dilatation, and 
the ensuing discussion of the function of the cervical monitor of the 
present invention will be based on dilatation. However, a practitioner of 
the medical arts will understand that these and other physiological 
measurements are interrelated, and that the monitoring and alarming 
function of the present invention is not dependent upon the particular 
placement of the probes 13, nor the particular path and distance that is 
monitored. 
Various preferred embodiments of the head of a disposable probes, two of 
probes which are used with the preferred embodiment of the ambulatory 
cervical effacement/dilatation monitor previously seen in FIGS. 2 and 3, 
are shown in FIG. 4, consisting of FIG. 4a through FIG. 4c. The body of 
the embodiments of FIGS. 4a and 4b is substantially cylindrical whereas 
the embodiment of FIGS. 4c is substantially spherical. The transducer of 
each of these two body configurations is in the substantial shapes of a 
three-dimensional, non-planar, bodies. This is somewhat unusual because an 
ultrasonic transducer is normally housed in a substantially planar 
parallelepiped body, typically a disk. Such need not be the case, however. 
The ultrasound, which is electrically produced in a crystal, will radiate 
from the surface of the surrounding housing, whatsoever its shape. 
Each of the preferred transducer bodies shown in FIGS. 4a-4c is 
characterized in that ultrasound emissions from the transducer occur along 
a multiplicity of axis in multiple different directions. The reason that 
the transducers are so omnidirectional is that, when secured to the wall 
of the cervix uteri of human female such as by a barbed fishhook or 
corkscrew coil (to be discussed), the transducers are substantially 
insensitive to their initial placement(s) and alignment(s), and also to 
any directional changes occurring before or during labor. The preferred 
transducers serve to maintain good acoustic coupling under all conditions. 
The particular construction of the preferred spherical transducer 
previously illustrated in FIG. 4c is shown in cross-sectional view in FIG. 
4d. A detail perspective view of this same transducer as assembled is 
shown in FIG. 4e. The preferred spherical transducer is formed from the 
union of two ceramic hemispheres coated on the interior and the exterior 
with metal. Each hemisphere is a polarized piezoelectric. Wired 
connections are as shown. The device is available from Channel Industries, 
Santa Barbara, Calif., U.S.A. 
It is, or course, necessary to maintain the transducers 13 in their 
predetermined, fixed, locations upon the cervix os 21 so that ultrasonic 
transit time measurements may be performed. That is the purpose of the 
holding device of the present invention. However, it should be 
preliminarily understood that no such separate holding device, per se, is 
absolutely necessary. There are insubstantial nerve endings on the cervix 
os, which is also physically very robust and resilient to permanent 
damage. Ultrasonic probes have heretofore been attached by corkscrews, and 
that embodiment of a probe 13 that is shown in FIG. 4b continues this 
tradition. Corkscrews are a good, and proven, means of attachment of 
probes to muscle, as witness cardiac pacemakers. However, there are 
differences between cardiac probes and ultrasonic transducers. In the 
former case an electrical signal is being coupled to the muscle, and 
reliable continuous electrical and physical contact must be maintained 
therewith. In the present ultrasonic probes, understand that no 
electrical, nor acoustical, energy is being attempted to be coupled into 
the muscle (of the cervix os) through, or by, the probe attachment. There 
is, or course, no electrical coupling to the muscle. The acoustic coupling 
is, by and large, to the surrounding mucous and fluids, and the probe is 
not configured for coupling acoustic energy into the cervix os (if it was 
then should lie tight against the cervix os). The probes' attachments are 
simply to hold the probes in position so that they may follow the movement 
of the muscle, and so that the varying distance between them may be 
monitored. 
So considering the function of the attachment of a probe 13, the barbs of 
the embodiments of FIGS. 4a and 4c, of like barbs in the substantial 
shapes of fishhooks, are preferred for some patients. Namely, the barbed 
probes are generally easier, and faster, to attach in patients who are 
sensitive to discomfort. A corkscrew probe should be unscrewed in order to 
remove, but a barbed probe of the design of FIGS. 4a and 4c will usually 
exit cleanly if simply pulled strongly. In those generally rare 
affixations, and locations, where a fishhook barb (not shown) better 
serves retention, and positioning of the probe, then the barb may be 
removed exactly as a fishhook is removed from the flesh of the body. 
Namely, the barb is worked forward to exit the surface, and is cut off as 
exposed. The barb-less probe is then withdrawn. 
Despite the fact that the performance of these methods and structures for 
probe affixation is unquestionably effective, there is a very great 
psychological problem in explaining to a woman that devices that look so 
"vicious" and so potentially injurious as do the barbed and corkscrew 
probes are to be affixed within in her body, and at a location thereof 
that she typically (wrongly) regards as sensitive. Furthermore, the barbed 
and corkscrew probes must be both inserted and extracted by the woman's 
obstetrician or other health care professional, and are not suitable for 
self-insertion or extraction. For these reasons, the alternative probe 
emplacement and holding system of the present invention will be shown 
commencing with FIG. 9. 
In the meanwhile, a graph showing a calibration of the preferred ambulatory 
cervical effacement/dilatation monitor is shown in FIG. 5a. The 
calibration is performed in the controller 11 by producing in manually 
controllable steps successive delays such as would be indicative, if 
received from probes 13, of an increasing amount of separation between the 
probes 13. The "manually controllable steps" simply involve the stepwise 
rotation of a multiple position switch which, in its successive positions, 
couples an increasing amount of delay into the simulated probe input to 
the controller 11 (the schematic diagram of which controller 11 will be 
shown in FIGS. 6 and 7). The lowest level of the trace in the graph of 
FIG. 5a is indicative of a probe separation of 10 mm; the highest level of 
the trace is indicative of a probe separation of 60 mm. If the number of 
steps are carefully counted, if may be observed that the preferred 
resolution of the cervimeter monitor 1 is at least as small as 5 mm. 
FIG. 5b is a graph showing the typical varying dilatation of the cervix 
uteri of a human female, or other higher primate such as a rhesus monkey, 
during labor. The total period shown is about thirty (30) minutes in which 
period twenty (20) relatively even cycles have transpired for an average 
cycle time of one and one-half (11/2) minutes per cycle. 
A schematic block diagram of a substantially analog first portion 11 of the 
preferred embodiment of the ambulatory cervical effacement/dilatation 
monitor 1 in accordance with the present invention is shown in FIG. 6. The 
first portion 11 is, in of itself, a complete sonomicrometer. 
Sonomicrometers are known in the art, and the circuit of the block diagram 
of FIG. 6 is simply a particular version of a sonomicrometer that is, 
quite obviously, adapted to the measurement task at hand in terms of (i) 
acoustic signal power, (ii) acoustic signal reception sensitivity, and, 
most importantly, (iii) the duration (not the frequency) of an acoustic 
signal pulse that will be appropriate to measure the distances involved in 
cervical dilatation, and (iv) a repetition rate of the acoustic signal 
pulse that will be appropriate to measure all changes in the distances 
involved in cervical dilatation. Notably, the frequency of the acoustic 
signal is an innate property of the probes, or transducers 13, which 
"ring" when electrically excited at their resonant frequency(ies). The 
probes, or transducers, 13 may suitably operate over a broad range of 
ultrasonic frequencies, and preferably ring at a natural resonant 
frequency of about 5 Mhz. 
A CLOCK portion of the CLOCK AND TIMING 111 produces a fundamental 1.58 MHz 
frequency. This frequency is chosen because an ultrasonic acoustic pulse 
will travel approximately 1 millimeter in tissue--and very nearly the same 
in mucous or other water-based fluids--in the period of one cycle of 1.58 
MHz, or 0.63 microseconds. The 1.58 Mhz signal is provided as signal CLOCK 
111. 
A TIMING portion of the CLOCK AND TIMING 112 produces pulses of (i) 50 
microsecond duration (of 1.58 MHz signal) (ii) at a pulse repetition rate 
of 100 Hz. The duty cycle of the collective pulses is correspondingly 
((5.times.10.sup.-5).times.1.times.10.sup.2) per second, or a low 0.5% 
which serves to save power. These 50 microsecond pulses at the 100 Hz. 
rate are applied to the set, or S, input of the PULSE GENERATOR 116 and 
the PINGER 114. The PINGER 116 serves as an amplifier. The 50 microsecond 
pulse duration is sufficient, when driven by the PINGER 114, so as to 
cause the driven one of the probes, or transducers, 13 to ring, producing 
an acoustic pulse (which gradually decays in amplitude) for an effective 
duration, as is such pulse is detectable at the other one of the 
transducers 13 and by the RECEIVER 118, of about 1 msec. (One hundred such 
acoustic pulses each second give an acoustic duty cycle of approximately 
10%.) The duration of this acoustic pulse is, or course, not particularly 
important save that each pulse shall have completely died away before a 
next later pulse is generated. In accordance with the principles of 
transit time sonomicrometry, it is the delay incurred by this pulse in 
reaching the receiving one of the probes, or transducers, 13 that is 
important. Each and every pulse will incur a delay of about 0.63 
microseconds per millimeter traversed. 
The signal developed in the RECEIVER 118 in response to each received 
acoustic pulse is shaped in an automatic gain control, AGC, circuit 120 
and is then subject to detection in LEVEL DETECT circuit 122. The signal 
AGC VOLTAGE 113 is a function of the amount of signal gain being applied 
in, and by, the AGC circuit 120, and will be highest when the received 
signal acoustic is lowest, or non-existent (as between acoustic pulses, or 
before an acoustic pulse has arrived). A use of such signal AGC VOLTAGE 
113 will be later shown in FIG. 7. The signal output of LEVEL DETECT 
circuit 122 will assume a logic High condition within a few tens of 
nanoseconds that the acoustic pulse is received by the RECEIVER 118. The 
signal will, as applied to the reset, or R, input of the PULSE GENerator 
circuit 114, serve to reset this circuit. (It will be understood that 
electrical delays are small in relation to acoustic delays in a 
sonomicrometer.) The signal PULSE 115 arising from the PULSE GENerator 
circuit 114 accordingly starts with each transmission of an acoustic 
pulse, and ends with the reception of the same pulse. Its duration is thus 
indicative of the acoustic delay in the communication of the ultrasonic 
pulse between the two transducers 13. 
FIG. 7 is a schematic block diagram of a substantially digital second, data 
logger and alarming, portion of the preferred embodiment of the ambulatory 
cervical effacement/dilatation monitor 1. This data logger and alarming 
portion receives all three signals 111, 113, and 115 developed in the 
analog, sonomicrometer, portion previously seen in FIG. 6. The signal 
CLOCK, which is at a frequency of 1.58 Mhz, serves to increment a COUNTER 
124 that is enabled for counting for the duration of signal PULSE 115. The 
number of counts accrued during the duration of each signal PULSE 115 is 
the thus the distance in millimeters that the ultrasonic acoustic signal 
traversed between probes 13 (shown in FIG. 6). Permitting the COUNTER 124 
to read directly in millimeters avoids the necessity of a later 
conversion. Once the count is terminated by the logic Low condition of 
signal PULSE 115, the COUNTER 124 will put the accrued count onto a 
digital communications bus that is called DIMENSION BUS 117 because it 
carries the cervical dimension. The COUNTER 124 will also reset itself to 
zero for the next counting interval (which, in accordance with CLOCK AND 
TIMING 112 shown in FIG. 6, will occur in 10 milliseconds). 
The current count, which is the cervical dilatation (or effacement) in 
millimeters, is received into a LATCH 126 and a COME circuit 128. The 
COME circuit 128 also receives a digital quantity from the PHYSIO LIMIT 
SET register 130. This quantity represents the greatest reasonable, 
real-world, change that would be expected in cervical dilatation over the 
time interval between successive counts, or 10 milliseconds. This quantity 
is equivalent to a change in cervical diameter of about 1 millimeter per 
second. The previous cervical measurement that was stored in LATCH 126 is 
compared with the current cervical measurement received via DIMENSION BUS 
117, and with the maximum expected change received from PHYSIO LIMIT SET 
register 130 in order to make the single determination that the 
presently-received cervical dimension either is, or is not, reasonable. An 
unreasonable reading might be received, for example, due to ultrasonic 
noise. If the cervical dimension, as is upon the DIMENSION BUS 117, is 
reasonable then the input from the COME circuit 128 to the AND gate 132 
is a logic High, satisfying one of the two inputs to AND gate 132. 
The other, remaining, input to the AND gate 132 is derived from 
differential amplifier 134. The signal 119 from this differential 
amplifier 134 will be a logic High, satisfying the remaining one of the 
inputs to AND gate 132, at such times as the signal AGC VOLTAGE 113 is 
greater than a preset signal level supplied from the reference voltage 
level, or LEVEL SET 136. The signal AGC VOLTAGE 113 will so be greater 
than the preset signal level supplied from reference voltage level SET 136 
when, and upon such times, as the RECEIVER 118 (shown in FIG. 6) is not 
receiving an ultrasonic pulse. According to being in an interval between 
the reception of ultrasound, the COUNTER 124 is not incrementing, and the 
cervical dimension that is upon the DIMENSION BUS 117 driven from the 
COUNTER 124 is (momentarily) stable, and invariant. Satisfaction of the 
AND gate 132 will produce a logic High gating signal to the DISPLAY 138, 
and will cause the DISPLAY 138 to capture the cervical dimension quantity 
that is upon the DIMENSION BUS 117 and to display it as a vertical bar in 
a next successive position proceeding towards the right across a visual 
display area. 
The display 138, if not substantially the entire data logger shown in FIG. 
7, may optionally, and even preferably, based upon a microprocessor. A 
practitioner of the digital logic design arts will have no difficulty in 
accomplishing the counting and comparison functions already discussed in 
FIG. 7, as well as certain other functions to be discussed, in the logic 
and the registers of a microprogrammed microprocessor. A microprocessor 
may, for example, scale the cervical dimension received on DIMENSION BUS 
117 in order to appropriately size, and place, a graphical display on the 
DISPLAY 138. Indeed, almost as soon as the practitioner of the digital 
logic design arts starts to think about the flexibility, and power, of a 
microprocessor as applied to the data logging and alarming task of FIG. 7, 
it is possible to realize that, other than the necessity of comparing 
analog signal levels in the differential amplifier 134 (and also in 
differential amplifier 140, yet to be discussed) and displaying data in 
the DISPLAY 138, veritably everything could be done in a microprocessor. 
In such a case FIG. 7 could be equally validly considered as a functional, 
as opposed to a hardware, block diagram. 
The preferred implementation of the monitor is, as is shown in FIG. 7, to 
(i) use a microprocessor (not shown) as part of DISPLAY 138, but (ii) not 
to place have all such functionality as might conceivably be accomplished 
by the microprocessor so accomplished. This is for two reasons not 
immediately apparent on the face of FIG. 7. First, it is contemplated 
that, with an appropriate data storage memory and sequential memory 
addressing (not shown) that a power-consuming microprocessor and a visual 
display might be turned off for periods of time and from time to time, 
saving energy when no one cares to view historical cervical dilatation 
(effacement) data in the DISPLAY 138. Second, and although various alarms 
the development of which is yet to be discussed are shown to be 
communicated directly to the DISPLAY 138, and presumably to any 
microprocessor (not shown) lodged therein, if is very simple to understand 
that, by use of discrete circuits no more complex than a latch, it would 
be possible to register, and to sound and/or display (in the form of a 
light, or LED), one or more alarms without the involvement of any 
microprocessor, or microcode program. Although outside the scope of the 
present disclosure, the data logging and alarming circuitry of FIG. 7 can 
thus readily be made to have (i) a reduced-power, fullback, operational 
mode, and/or (ii) substantially fail-safe operation. 
An alarming monitor of cervical dilatation/effacement does not incur the 
reliability requirements of, for example, a cardiac pacemaker. If the 
instrument fails the patient neither aborts, nor gives birth, nor suffers 
any adverse effects whatsoever. However, it is anticipated that, in some 
pregnancies, successful live birth may be dependent upon the adequacy and 
continuity of the cervical monitoring, and the timely administration of 
all such interventions (primarily drugs) as are indicated to be prudent 
and necessary as a result of such monitoring. Accordingly, the cervical 
dilatation (or effacement) monitor is desirably, and is, constructed as a 
quality instrument, with due regard by design for its potentially crucial 
function. 
Continuing in FIG. 7, a battery (not shown), nominally of a 9 v.d.c. type 
which typically suffices to last at least two (2) weeks and more commonly 
two (2) months in continuous use, produces a battery voltage BATT VOLTS 
121. This battery voltage is compared in differential amplifier 140 to the 
voltage output of a constant voltage circuit LEVEL SET 142. Until, an 
unless, the battery voltage falls below a predetermined level, normally 
eight (8) v.d.c., the signal ALARM 123 will be maintained a logic High 
level, and the DISPLAY 138 will not produce an alarm. At any such times as 
the battery voltage were to fall below the predetermined level the signal 
ALARM 123 will go to a Logic Low level, and the DISPLAY 138 will produce a 
visual and/or audible alarm in plenty of time to replace the battery (not 
shown) before power reserves are exhausted. 
A comparison of the cervical dilatation (effacement) measurement as is 
present on the DIMENSION BUS 117 is made in, and by, COME circuit 144 
to a predetermined dimension that is stored in the DIMN ALARM SET register 
146. The DIMN ALARM SET register 146 is intended to contain a maximum 
dimension in the case of evaluating cervical dilatation, or, conversely, a 
minimum dimension in the case of evaluating cervical effacement, which, 
when the cervical dimension is respectively greater than or less than the 
stored dimension, is indicative that labor has begun (or at least of an 
extreme cervical condition). The result of the comparison is communicated 
to OR gate 148 as a logic High signal in the event that the threshold is 
exceeded. The predetermined dimension that is stored in the DIMN ALARM SET 
register 146 is preferably adjustably so predetermined, and stored. A 
microprocessor (not shown, typically closely associated with DISPLAY 138) 
may facilitate this storage, normally of a value that is determined by the 
attending physician or obstetrician. 
In a similar manner, another comparison of the cervical dilatation 
(effacement) measurement made in, and by, COME circuit 152 to a 
predetermined dimension that is stored in the DIMN RATE ALARM SET register 
152. Notably, the cervical dimension is not even transferred to the 
COME circuit 152 until the COME circuit 144 is satisfied, meaning 
that a threshold cervical dilatation/effacement measurement has been 
exceeded. The DIMN RATE ALARM SET register 152 is intended to contain a 
minimum rate of the change of dimension cervical dilatation, or 
effacement. This quantity is involved once labor has begun (which was 
presumptively determined by satisfaction of COME Circuit 144). If the 
predetermined rate of change is not exceeded then this may be indicative 
of problems with the progress of labor. The result of the comparison is 
also communicated to OR gate 148 as a logic High signal in the event that 
the predetermined rate of change is not exceeded. The predetermined rate 
of change that is stored in the DIMN RATE ALARM SET register 152 is 
preferably adjustably so predetermined, and stored. A microprocessor (not 
shown, typically closely associated with DISPLAY 138) again facilitates 
this storage, normally again of a value that is determined by the 
attending physician or obstetrician. 
Satisfaction of the OR gate 148 produces a logic High signal ALARM 125, 
which signals received into DISPLAY 125 is used to produce a visual and/or 
audio alarm. 
A flow chart of the function of the preferred embodiment of the ambulatory 
cervical effacement/dilatation monitor 1 is shown in FIG. 8. The flow 
chart is, as well as being functional, suitable to serve as the flow chart 
of a sequential controller, particularly (but not necessarily) including a 
microprogrammed microprocessor. It will be recognized by a practitioner of 
the digital circuit design arts that the relative simplicity of the 
functional control block diagrammed in FIG. 8 may be accomplished by, and 
in, many alternative circuit implementations including, but not limited 
to, a microprogrammed microprocessor circuit. 
The function of the ambulatory cervical effacement/dilatation monitor 1 
commences with BEGIN block 800 upon application of power, and proceeds to 
commencing ultrasound transmission with ENABLE PINGER block 802. An 
ultrasound, or "ping", transmission count N is incremented in block 804, 
and inquiry is made as to whether this count has exceeded 100 in block 
806. As will be developed in the further explanation of FIG. 8, it is a 
highly abnormal condition, indicating that at least 101 ultrasound pulses 
have been transmitted with no intervening receptions, if N is greater than 
100. In such an eventuality, transducer or transducer interconnect 
hardware failure is indicated, and a TRANSDUCER ALARM is sounded in block 
808 and the monitor 1 brought to a STOP in block 810. 
Normally block 806 is satisfied, and the inquiry as to whether the 
Automatic Gain Control (AGC) voltage is greater than a threshold--AGC 
VOLT&gt;THRESHOLD--is made in block 812. If not, no ultrasonic pulse has as 
yet been received, and the transmission process is re-enabled commencing 
with block 802. 
If a received pulse is detected in block 812, then a reasonability check on 
the detected delay is performed in block 814. It is therein inquired as to 
whether the detected change is within the physiological limits of the 
human subject, IS CHANGE&lt;=PHYSIO LIMIT? In the event that it is not, 
process error has occurred and the transmission process is again 
re-enabled commencing with block 802. 
If, however, all status and reasonableness checks of blocks 806, 812 and 
814 are satisfied, block 816 is entered to assess whether the change in 
measurements dictates a rate alarm. If the measurement change does not 
exceed the predetermined alarm threshold, then DELTA MEAS&lt;RATE ALARM? is 
answered yes and block 820 is entered. Should, however, the measurement 
change exceed the predetermined alarm threshold, then an ALARM is 
indicated in block 818. 
Similarly, block 820 is entered to assess whether the absolute magnitude of 
the measurement dictates an alarm. If the measurement change does not 
exceed a predetermined alarm threshold dimension, then MEAS&lt;DIMN ALARM? is 
answered yes and block 822 is entered. Should, however, the measured 
dimension exceed the predetermined alarm threshold dimension, then an 
ALARM is indicated in block 824. 
Whether a dimension, or a dimensional change, has occasioned the respective 
ALARM of block 824, of or block 818, or not, the block 822 DISPLAY MEAS is 
always entered and the measurement displayed. The count number of the 
ultrasound transmission is thereafter reset to zero--SET N=0--in block 
824, and the entire loop process re-entered at block 802. 
The present invention concerns a particular, preferred, biomedical 
instrumentation probe holding system that is particularly useful with the 
cervical dilatation monitor described above, and with long term use of 
this monitor during pregnancy. A diagrammatic perspective view of a first 
embodiment of such a device for holding medical instrumentation sensors at 
and upon the cervix os of a human female in accordance with the present 
invention is shown in FIG. 9. The device 90 is in the substantial shape of 
an annular disc. It is preferrably constructed entirely of surgical grade 
latex rubber, although the elastic modulus of the rubber used may, and 
desirably does, vary across the radius of the annulus, being strongest and 
most elastic to the exterior. 
The exterior rim region 91 is normally possessed of an integral ring of 
substantially circular cross section and typically several millimeters 
diameter. The ringed rim region 91 has a shape memory. It is not 
appreciably subject to losing this memory over the durations and body 
temperatures of use, and will always be elastic to resume its original 
shape and circular contour. 
The interior rim region 93 is likewise normally possessed of an integral 
ring again of substantially circular cross section and typically several 
millimeters diameter. This ringed rim region 93 also has a shape memory. 
However, this memory is not permanent, and the rim region 93 will, if held 
stretched indefinitely for durations in excess of days at body 
temperature, assume a slight "set", and become less forceful to resume its 
absolutely original shape and circular contour. The interior rim region 93 
is, mind you, always elastic, and will when deployed at the cervix vary in 
size, including cyclically, with the cervix os. It is simply that, should 
it be called upon to expand in diameter by a factor of two or three, the 
interior rim region 93 will not become more and more elastically resistant 
to further expansion (like a rubber band) but will, in fact, exhibit about 
the same resistance to stretching throughout a broad range. 
The interior rim region 93 is connected to the exterior rim region 91 by an 
elastic annulus region 92 that is typically quite thin and like onto the 
thin latex elastic of a condom or female diaphragm. There need be very 
little mechanical strength provided by this region, and its regional 
rupture is both uncommon (when situated in operative position) and without 
substantial effect on holding function of the device 90. The annulus 
region 92 is accordingly normally made quite less than a millimeter in 
thickness. 
The dimension X is typically one to two centimeters (1-2 cm.), and the 
dimension Y four to six centimeters (4-6 cm.) as the size of the female 
patient wearer dictates. 
One or more biomedical probes, and particularly two ultrasonic transducers 
130, are held by the device 90, preferably in and by cavities 931 of 
complimentary shape and size located at the interior rim region 93 of the 
device 90. The transducers 130 are tightly permanently held and 
directionally disposed to point at each other across the circular central 
opening of the annulus. Wires 131 to each of the transducers 130 are 
preferably housed in integral conduits, or channels, 932 within the body 
of the device 90 at each of its interior rim region 93, its elastic 
annulus 92 and its exterior rim region 91. These integral conduits, or 
channels, 932 serve to direct the wires 131 at a substantial right angle 
to the plane of the device 90 where the wires 131 exit the exterior rim 
region 91. The integral conduits, or channels, 932 may alternatively 
direct the wires 131 to a single point on the exterior rim region 91 (not 
illustrated). 
The wires 131 preferably terminate in a plug connector 132 that is in turn 
plug connected to the PINGER 115 and the RECEIVER 118 of the cervical 
dilatation/effacement monitor shown in block diagram in FIG. 6. 
A cross-sectional plan view of the probe previously seen in FIGS. 4c-4e in 
position about the cervix os, and within the vaginal canal, of a human 
female is shown in FIG. 10--primarily for ease of comparison to FIGS. 
12-16. The barbed transducers 13 are hooked into the tissue of the cervix 
os. 
A cross-sectional plan view, similar to the view of FIG. 10, of the 
first--diaphragm-like--embodiment of e holding device 90 in accordance 
with the present invention (previously seen in FIG. 9) located in position 
about the cervix os, and within the vaginal canal, of a human female, is 
shown in FIG. 11. The exterior rim region 91 contacts and engages the 
interior walls of the vaginal canal 22. Probes 13a are held, as will be 
shown in more detail in FIG. 14. 
A cross-sectional plan view of a second--cervical-cap-like--embodiment of 
an annular holding device 90a in accordance with the present invention is 
shown in FIG. 11. The second embodiment holding device 90a is retained in 
position by compressively embracing the cervix os. 
The cross-sectional plan view of the second embodiment of a holding device 
90a in accordance with the present invention again shows the device to be 
in the substantial shape of planar annular disc, now shown slightly 
deformed in deployed position. The main difference between the embodiments 
is (i) size, and (ii) the tension, and elasticity, of the central annulus 
region 92 (shown in FIG. 9). The central annulus region 92a of the first 
variant 90 shown in FIG. 12 is more taught, and more tightly elastic. 
Either of the embodiments 90, 90a functions roughly equivalently, and 
equally satisfactorily, to hold position at and about the cervix os 21. 
It should be understood that the ultrasonic transducers 13 (shown in FIG. 
9) are not only positioned to the cervix os 21 in a relative sense, and 
may be or become slightly differently disposed, giving a correspondingly 
slightly different measured distance of separation, from time to time, and 
from one insertion of the device 90 to another. The precise measurement of 
the diameter of any one woman's cervix os is, or course, neither the 
requirement nor the purpose of dilatation monitoring. It is the changes, 
and cyclical changes, in probe separation incurred over time that are of 
interest, and importance, and not the absolute distance of separation of 
the probes. The dilatation monitor so responds, and is "self-normalizing". 
It is accordingly necessary only that the holding device 90 of the present 
invention should hold the probes stably, and to less than the deviations 
in cervical dimensions, over the typically several minute duration 
dimensional variations of labor. This the holding device 90 does. It is 
typically sufficient to hold the probes 13 at a constant uniform 
separation (the cervix os remaining constant) not varying by more than a 
few millimeters, if at all, during the course of one day of the wearer's 
normal activities. 
Yet another cross-sectional plan view, similar to FIGS. 10-12, showing a 
third--female-condom-like--embodiment of a holding device 90b in 
accordance with the present invention in position about the cervix os, and 
within the vaginal canal 22, of a human female, is shown in FIG. 13. The 
annular holding device 90b is expanded from the annular device 90 of FIG. 
9 for additionally incorporating a large tube 94. The device 90b with its 
tube 94 is shown in deployed position about the cervix os 21 and within 
the vaginal canal 22, of a human female 2 (shown in FIG. 2). The tube 94 
is preferably integral with the device 90b, and is an extension at and 
from the exterior rim region 91 (shown in FIG. 19). The region 91 is still 
suitably called a "rim" region, even though it not longer represents the 
termination of the body of the device 91, because it is of maximum 
diameter to the whole of the device 91, and because the tube 94 extends 
downwards in the vaginal canal 22 from this "rim" region 91 in the manner 
of female condom. 
Continuing in FIG. 13, the wires 131 are desirably routed to the interior 
of the tube 94 where they are, quite obviously, out of contact with the 
wall of the vaginal canal 22. The wires normally run free inside the 
region of tube 94, and lower, however, and are not further sheathed in any 
continuation of any optional conduits, or channels 932 (shown in FIG. 9). 
This is so as to prevent that this narrow region should become a path for 
the migration of bacteria such as might cause infection. 
A detail cross-sectional plan view, similar to FIG. 11, of the 
first--diaphragm-like--embodiment of a holding device 90 in accordance 
with the present invention is shown in FIG. 14. The device 90 holds probes 
13a, normally two ultrasonic transducers, in the indicated positions about 
the cervix os 21, and within the vaginal canal 222, of a human female. 
A detail cross-sectional plan view, similar to FIG. 12, of the 
second--cervical-cap-like--embodiment of a holding device 90a in 
accordance with the present invention is shown in FIG. 15. The device 90a 
holds two ultrasonic transducers 13a in first positions about the cervix 
os 21, and within the vaginal canal 22, of a human female. 
The transducers 13a need not be, however, held in the specific position 
illustrated in FIG. 15. A detail cross-sectional plan view of the same 
second--cervical-cap-like--embodiment of a holding device 90a in 
accordance with the present invention now holding two ultrasonic 
transducers 13a in second positions about the cervix os 21, and within the 
vaginal canal, of a human female. The rim region 91a, and the central 
aperture region 93a, of the second embodiment device 90a perform like 
functions as do the regions 91, 93 of the first embodiment device 90 
illustrated in FIG. 9. 
The probes 13 are commonly glued to surface of the holding devices 90, 90a 
shown in FIGS. 14-16 by non-biologically reactive adhesive 95. 
A perspective view of the first--diaphragm-like--embodiment of an annular 
ring holding device 90 in accordance with the present invention with two 
ultrasonic transducers 13a mounted so that their wire connections 131 
extend outboard and over the rim region 91 of the annulus is shown in FIG. 
17. Another perspective view of the same first--diaphragm-like--embodiment 
of an annular ring holding device 90 in accordance with the present 
invention now having the two ultrasonic transducers 13a mounted so that 
their wire connections 131 extend through the central aperture of the 
annulus is shown in FIG. 18. 
A perspective view of a variant of the first--diaphragm-like--embodiment of 
an annular ring holding device 90 (variant) in accordance with the present 
invention is shown in FIG. 19. In the variant device 90 (variant) the 
wires of two mounted ultrasonic transducers 13a that mounted are sheathed 
in their passage through the central aperture of the annulus and away from 
the annulus by the tube 96. 
A perspective view of the second--cervical-cap-like--embodiment of an 
annular ring holding device 90a in accordance with the present invention 
is again shown in FIG. 20. Two ultrasonic transducers 13a are mounted so 
that their wire connections 131 extend through the central aperture of the 
annulus. 
A cross-sectional view of the second--cervical-cap-like--embodiment of an 
annular ring holding device 90a in accordance with the present invention 
is again shown in FIG. 21. The two held ultrasonic transducers 13a mounted 
to the holding device 90a are disposed on opposite sides of a cervix os 21 
that has not undergone either dilatation nor effacement. A cross-sectional 
view of the same second--cervical-cap-like--embodiment of an annular ring 
holding device 90a in accordance with the present invention previously 
seen in FIG. 21 is again shown in FIG. 22, only the two held ultrasonic 
transducers 13a mounted to the holding device 90a are disposed on opposite 
sides of a cervix os that has undergone both dilatation and effacement. It 
may be noted that the transducers 13a still hold position, as desired. 
In accordance with the preceding explanation, many variations and 
alterations of the preferred embodiment of the present invention will 
suggest themselves to a practitioner of the electronic medical equipment 
design arts. For example, many more separate, and detailed, alarms could 
be made contingent upon conditions which may be quite intricate, and 
convolute. For example, the display, and history display, could be of 
alternative intervals and epochs. For example, the holding device could be 
intrusive into the cervix, and could also hold one or more instrumentation 
probes at and in contact with the walls of the womb or the placenta. 
In accordance with these and other possible variations and adaptations of 
the present invention, the scope of the invention should be determined in 
accordance with the following claims, only, and not solely in accordance 
with that embodiment within which the invention has been taught.