Specimen test slide and method of testing for fecal occult blood

A specimen slide in accordance with the present invention comprises a front panel including a test material placement side and a portion of a test sheet, the test material placement side including at least one aperture which is configured to accept a test sample through the aperture onto the test sheet, and a back panel including a developing side through which the opposite side of the test sheet is exposed. An indicating means is located on the developing side portion of the test sheet within proximity to, but not directly on, the portion of the test sheet directly opposite to the aperture.

FIELD OF THE INVENTION 
The present invention relates to devices and methods for testing specimens 
and more particularly to an improved specimen test slide for fecal occult 
blood. 
BACKGROUND OF THE INVENTION 
Fecal occult blood testing has become a popular, widely used procedure 
useful in the detection of relatively small amounts of blood in fecal 
specimens. This wide use and popularity arises primarily because fecal 
occult blood testing is non-invasive, simple and inexpensive to perform. 
Because the presence of fecal occult blood in a specimen is a symptom that 
may be associated with colon cancer or a precursor to colon cancer, fecal 
occult blood testing is often routinely used as a screening tool. The 
routine screening of patients by means of fecal occult blood testing has 
helped to detect colon cancer at a stage where the disease is readily 
treatable. 
A popular form of fecal occult blood testing utilizes a guaiac treated test 
sheet where a fecal material specimen is smeared on a front, or, "test 
material placement" side of the test sheet. The fecal material has a 
tendency to diffuse through the test sheet, defining a region on a side of 
the sheet opposite to the test material placement side. The portion of the 
sheet opposite to where the test material is smeared is the back, or, 
"developing" side of the sheet, and the area on the developing side of the 
test sheet where the fecal material diffuses through from the test 
material placement side of the test sheet is referred to herein as the 
"diffused region" or the "diffused area". A developing solution is applied 
to the developing side of the sheet directly onto the diffused region, and 
if a color change is indicated, blood may be present in the fecal 
specimen. 
There has been an on-going need to obtain, transport and process the 
specimens of the fecal occult blood test in a manner that is as convenient 
and as aesthetically acceptable as possible. One form of specimen 
collection device that has gained wide popularity is a slide formed from 
folded paper or cardboard. The slide includes guaiac treated paper to 
which the fecal specimen is applied through a "test window" or "aperture" 
located on the test material placement side of the test sheet, and a cover 
which is closed once the specimen application is completed. A flap in the 
back of the slide may be opened to reveal the developing side of the 
guaiac treated paper for subsequent application of developer onto an area 
of the developing side of the test sheet directly opposite to the aperture 
or apertures, i.e., directly onto the diffused region. A positive result, 
that is, one indicating the presence of blood in the fecal sample, is 
determined by the presence of (usually) a blue color, and the intensity 
thereof provides further information as to the amount of blood present in 
the fecal sample. 
Specimen slides for fecal occult blood tests generally have test windows of 
varying sizes. In an attempt to standardize the sample amount applied 
through the test windows and in an effort to mitigate against over- or 
under- application of sample, instructions for sample application are 
ordinarily provided to the patient. These instructions vary, but are 
generally intended to provide direction to the patient in an effort to 
limit the amount of sample smeared into the test window, i.e., "apply a 
thin smear"; "a pea size"; or "the size of a match head". The quantity of 
the sample on the slides returned to the laboratory varies from trace 
amounts, which are insufficient for proper testing, to very excessive 
amounts, which also create technical, as well as aesthetic, problems. It 
is often the case that when there is too much sample on the test material 
placement side, the developing side of the slide is fully covered with the 
colored stain of the diffused sample. This makes reading of test results 
based on color intensity difficult and usually impossible. 
Errors on the part of the technician developing the test slide may also 
occur. For example, if the technician inadvertently adds developer to the 
test material placement side of the test slide, as opposed to the 
developing side, the sample can be flooded with the developing solution, 
leading to incomprehensible, incorrect or misleading results, due to 
reconstitution of the sample. Furthermore, the instructions for 
application of the developing solutions require application thereof 
directly onto the diffused region. It is often the case, particularly when 
an insufficient amount of sample is present, that far too much developing 
solution will be added directly onto this area in an attempt to compensate 
for the lack of sufficient sample. This also has the effect of flooding 
the diffused region, which can result in incomprehensible, incorrect or 
misleading results, i.e. the intensity of the color can be artificially 
altered. 
Most of the problems associated with differing amounts of sample added to 
the test slide by the patient are predicted upon the inexperience of the 
patient with such test slides. Given the very nature of, for example, 
fecal sample materials, different individuals will react differently to 
applying such a sample to a test slide. Therefore, while instructions can 
be provided to the patient as to how much of a sample should be placed in 
the test window area, consistent amounts of sample across of wide-ranging 
group of patients are not obtainable, as experience has demonstrated. 
Additionally, the technician who attempts to develop a test on a test 
slide that includes either inadequate or excessive amounts of sample could 
possibly provide incorrect results to the patient or the patient's 
physician; thus the medical technician who attempts, albeit incorrectly, 
to compensate for incorrect sample amounts could possibly provide the 
patient or the patient's physician with results that do not lead to 
additional (and necessary) tests, or with results that lead to additional 
(but unnecessary) tests. Thus, the technician who provides such erroneous 
results could be exposed to legal liability. 
Because the performance of the test is dependent on the reproducibility, 
ease of use by patients, as well as efficient, yet simple, 
sampling/developing procedures, an improved specimen test slide taking the 
above factors into account is not only desirable, but necessary. 
SUMMARY OF THE INVENTION 
The present invention overcomes the limitations and drawbacks noted above. 
A most preferred embodiment of a specimen slide in accordance with the 
present invention comprises a front panel including a test material 
placement side and a portion of a test sheet, the test material placement 
side including at least one aperture which is configured to accept a test 
sample through the aperture onto the test sheet, and a back panel 
including a developing side through which the opposite side of the test 
sheet is exposed. An indicating means is located on the developing side 
portion of the test sheet within proximity to, but not directly on, the 
portion of the test sheet directly opposite to the aperture. The location 
of the indicating means relative to the aperture is critical and essential 
to the performance of the specimen slide. The indicating means is most 
preferably a target printed directly onto the test sheet. 
The size and shape of the aperture is configured such that the aperture is 
completely filled with the test sample. The width of the aperture is 
preferably less than the height of the aperture. Two apertures are most 
preferably included in the front panel, and the juxtaposition of the 
apertures is such that the inner edges thereof are substantially 
non-parallel with each other. Most preferably, the apertures have a 
"letter C" configuration such that the interior portion of each "letter C" 
aperture faces the indicating means. 
The location of the indicating means relative to the aperture is such that 
when a developing solution is added onto the indicating means, the 
solution migrates completely through the portion of the test sheet 
directly opposite to the aperture. 
To use the specimen slide, the patient completely fills the aperture with, 
e.g., a fecal specimen. A developing solution is then added onto the 
indicating means. The solution, having a tendency to migrate across the 
test sheet, migrates through an area of the test sheet directly opposite 
to the aperture, including the diffused region. By specifically locating 
the indicating means at a defined location relative to the aperture, the 
developed solution migrates away from this stained region, which 
surprisingly and unexpectedly enhances the color intensity of the 
developed solution, and hence the readability of the color intensity, as 
compared to previous specimen test slides.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
With reference to FIG. 1 and 2, a most preferred embodiment of a device in 
accordance with the present invention is in the form of a specimen slide 
100 and includes a front panel 105, with a corresponding front panel cover 
flap 107 (shown in an open position in FIG. 1) and a back panel 115, with 
a corresponding back panel cover flap 117. Panel 105 includes in the 
central region thereof a test material (sample) placement area which 
preferably includes two apertures 110, 120 and test sheet 101 of absorbent 
material fixed between the front panel 105 and back panel 115. 
Cover flap 117 (shown in its open position in FIG. 2) is defined in the 
back panel 115 by an outline of perforations 111 and a crease 130 which 
serves as a hinge. The perforations 111 are spaced to define a plurality 
of bridges, each bridge comprising bridge portions 117a and 117b. The 
bridges hold flap 117 in place until the bridges are broken as flap 117 is 
opened along the perforations 111 to reveal the backside of test sheet 
101. In the embodiment disclosed herein, sheet 101 is filter paper which 
carries a reagent which will react with hemoglobin components from blood 
and a peroxide solution to form a visible colored compound. In the 
embodiment disclosed herein, test sheet 101 is Whatman Grade #1 filter 
paper (Whatman Paper Ltd., Springfield Mill, Kent, United Kingdom). The 
reagent may be, for example, guaiac, tetramethyl benzidine, ortho 
tolidine, and other similar chromogens. In the embodiment disclosed 
herein, the reagent carried by the sheet 101 is guaiac. An area defining 
monitors suitable for indicating the performance of the guaiac carrying 
test sheet 101 and reagents which may be applied thereto is indicated at 
200 and may be of the form described, for example, in U.S. Pat. No. 
4,365,970. 
The specimen slide 100 is preferably formed from a single sheet or panel of 
paper or cardboard. The cardboard is die-cut to form apertures 110 and 120 
(best viewed in FIG. 1 and shown in phantom in FIG. 3), as well as the 
perforations to define flaps 107 and 117. A tab 109 is also formed at the 
other edge of flap 107. Tab 109 is adapted to engage a semi-circular slit 
109a formed near an outer edge 150 of the frontal panel 105. The slit 109a 
is also formed by, for example, die-cutting during the manufacturing 
process of the slide 100. 
Specimen sheet 101 is positioned and fixed by a suitable adhesive or glue. 
The front and back panels 105 and 115 are folded along the edge 150 and 
are pressed and held together by means of a suitable glue or adhesive. A 
drop of glue 190 holds the front panel 105 and front panel cover flap 107 
together until slide 100 is ready for use. 
In order to effectuate the placement of developing solution onto test sheet 
101, means are provided for indicating the placement of the developing 
solution onto test sheet 101 onto an area of the test sheet opposite to 
apertures 110 and 120. For example, a target area, preferably in the form 
of a target 830 (FIG. 2 and FIG. 3), can be printed directly onto test 
sheet 101. Target 830 is the most preferred means for directing the 
medical technician to apply the developing solution onto the test sheet 
101. Alternative means for indicating can include, for example, any 
printed locator for directing the placement of the developing solution 
onto test sheet 101. 
The location of the indicating means is critical. By ensuring that the 
indicating means is properly located relative to the aperture(s), then 
irrespective of the size, shape or specific juxtaposition of the 
aperture(s), or the specific type of filter paper utilized, the advantages 
derived herein can be realized. In effect, the location of the aperture 
relative to the indicating means is determined by the objective of 
ensuring that the developing solution can contact the test sample, react 
therewith to form a reaction product (if any), and carry any reaction 
product away from the stained region onto a relatively clean area of test 
sheet 101 adjacent to such a stained region. For these reasons, the 
location of the indicating means is advantageously located relative to the 
location of the aperture, as will be described in detail below. 
With reference to FIG. 3, and with respect to the embodiment disclosed 
herein, target 830 is advantageously located between about 1.5 and about 
2.5 times, and preferably about 2.0 times the width of an aperture from 
outer edges 110a and 120a of apertures 110 and 120, respectively. As used 
herein, the term "outer edge" is defined as the edge of an aperture 
located furthest from the target area as defined, including target 830, 
"inner edge" is defined as the edge of the aperture opposite to the outer 
edge, and "times" is an alternative term to the mathematical expression 
referred to as "multiplication" or "multiplied". 
As an alternative method for locating the indicating means relative to the 
aperture, the distance between the outer edge of one aperture and the 
outer edge of at least one other aperture is advantageously between about 
3.0 and about 5.0 times, and preferably about 4.0 times the width of an 
aperture such, that the indicating means is located at the midpoint 
between the apertures. As a further alternative, the indicating means is 
advantageously located between about 2.0 and about 4.0 times and 
preferably about 3.0 times one half of the width of the aperture from the 
approximate center of the aperture. As used herein, the "approximate 
center" of each aperture is defined as a point approximating call-out 
designations 110d and 120d (FIG. 3). i.e. a point located interior to an 
aperture at a point approximating about one-half of the height and about 
one-half of the width. 
Preferably, the width of the aperture is less than the height of the 
aperture. "Height" is defined as the measured distance "h" in FIG. 1 and 
width is defined as the measured distance "w" in FIG. 1. The height of the 
aperture is advantageously about 5 times to about 1.5 times than the width 
of the aperture. Most preferably, the height is about 4 times the width of 
the aperture. The width is advantageously about 0.25 cm to about 1.00 cm 
and most preferably about 0.50 cm in length. 
When two apertures are utilized, it is essential that the inner edges of 
the apertures be substantially non-parallel with each other. As used 
herein, the term "parallel" is accorded its usual definition, e.g. 
everywhere equidistant. "Substantially non-parallel" as used herein is 
indicative of the relative relationship between the inner edges of the 
aperture. Thus, the inner edges of the two apertures are substantially 
non-parallel if the distances between the inner edges are substantially 
non-equidistant. When more than two apertures are utilized, it is 
essential that the inner edges of the apertures be substantially 
non-partallel with each other as previously disclosed. When a single 
aperture having a straight line inner edge is utilized, it is essential 
that the distance between the top inner edge corner of the aperture and 
the indicating means be substantially greater or substantially less than 
the distance between the inner edge corner opposite to the top inner edge 
corner and the indicating means. Under this scheme, the indicating means 
can be described as the apex of a triangle, whereby the triangle is formed 
by: a line from the indicating means to the top inner edge corner; the 
inner edge; and a line from the inner edge corner opposite to the top 
inner edge corner and the indicating means. In this scenario, the triangle 
thus formed is not an equilateral triangle, given the length differentials 
described above. 
Most preferably, the inner edge of each aperture(s) is curvilinear in 
nature such that a portion of the inner edge, or the entire inner edge, is 
bounded by a curved line. If only a portion of the inner edge of an 
aperture is curvilinear, the remaining portion thereof can be parallel 
with the inner edge of another aperture. In such a situation, at least 
one-half of the inner edge is preferably curvilinear. The curved line is 
advantageously positioned interiorly to the aperture(s). By way of example 
and not limitation and referencing FIG. 3, inner edge portion 110c and 
inner edge portion 120c are parallel to each other; however, inner edge 
portion 110b and inner edge portion 120b are curvilinear such that the 
inner edges of aperture 110 and 120 are substantially non-parallel to each 
other. 
The outer edge of each aperture can also be curvilinear in nature. Most 
preferably, the entire outer edge is curvilinear. Accordingly, in the most 
preferred embodiment, the apertures each have a "letter C" configuration. 
As used herein, the term "letter C" configuration is meant to describe the 
configurational shape of an aperture as depicted in FIG. 1 and FIG. 3. 
Most preferably, the apertures each face one another. 
For the embodiment disclosed herein, the most preferred measurements for 
the apertures would be such that the height of each aperture is about 2.0 
cm, the width of each aperture is about 0.5 cm, and the distance between 
the outer edges of the apertures is about 2.0 cm, such that the distance 
between the outer edge of each aperture and target 830 is about 1.0 cm and 
the distance between the approximate midpoint of each aperture and target 
830 is about 0.75 cm. 
In using the specimen slide 100, fecal specimens are placed onto test sheet 
101 through apertures 110 and 120 such that the specimens completely fill 
apertures 110 and 120. The patient closes the specimen slide 100 by 
folding front panel cover flap 107 along crease 230 and inserting tab 109 
beneath slit 109a. The specimen slide 100 is transported to the 
physician's office or laboratory for analysis. With reference to FIG. 2, 
the analysis of the fecal specimens carried by specimen slide 100 may be 
accomplished in an advantageous manner, i.e. without reopening the 
specimen slide 100 at front panel cover flap 107 to gain access to 
apertures 110 and 120. Back panel cover flap 117 is opened by separating 
bridge portions 117a from 117b. A developing solution is applied to the 
back of the test sheet 101 onto target 830 to form a screening test for 
occult blood in the specimen. 
Developing solution is most usually applied via a drop-wise application to 
the developing side of filter paper 101. As such, as these drops come in 
contact with test sheet 101 and are absorbed therein, there is a tendency 
for the solution to migrate outwardly from the point of contact, usually 
in a radial direction. Two to three drops of developing solution are added 
to the test sheet 101 by addition thereto onto target 830. After testing, 
the entire slide 100 may be properly disposed of. 
Sheet 101 may be sensitized for other analytes and the device may be 
adapted for collecting other types of specimens, such as mucosic, viscous 
materials. Several slides may be attached side-by-side, each having a 
different reagent on sheet 101, such that testing of several analytes can 
be effectuated. 
Different filter papers can be utilized for test sheet 101 such that 
adjustment of the location of the outer edges of the aperture(s) relative 
to the location of the target area or to one another is possible. 
Preferably, the composition of the filter paper is cotton fiber, although 
wood/cotton fiber or glass/cotton fiber combinations can be utilized. 
Three factors are of importance in determining the location of the outer 
edges of the apertures relative to the target area, these being the 
thickness, particle size relation and flow rate of the filter paper. 
The thickness of the filter paper is preferably between about 0.10 mm and 
about 0.26 mm. Most preferably the thickness of the filter paper is about 
0.175 mm. When a filter paper is used that has a thickness in excess of 
about 0.175 mm, it is possible that the area in which developing solution 
travels may correspondingly decrease; the opposite is possible for a 
filter paper that has a thickness less than about 0.175 mm. In order to 
compensate for these variables, at least two approaches are possible: (1) 
altering the amount of developing solution added to the filter paper; or 
(2) adjusting the location of the outer edges of the apertures relative to 
the target area. Thus, for a filter paper having a thickness greater than 
about 0.175 mm, more than two to three drops of developing solution can be 
utilized (about three to four drops), or the aperture, and hence, the 
outer edges of the aperture, can be moved closer to the target area. The 
opposite is suggested for filter paper having a thickness less than about 
0.175 mm. I.e., less than about two drops of developing solution can be 
utilized (about one drop) or the aperture, and hence the outer edge of the 
aperture, can be moved further from the target area. 
The particle size retention of the filter paper is defined herein as the 
average size of a spherical particle retained by a given filter paper with 
a 98% efficiency as determined using an electronic particle counter. 
Preferably, this value is relatively small, on the order of from less than 
about 1.0 micron to about 7.0 microns. Most preferably, the particle size 
retention is about 4.0 microns. The value for the particle size retention 
cannot be such a value that too much of the sample is able to "leak" 
through the filter paper, while at the same time if the value is too 
small, the sample will not properly diffuse through the filter paper. 
Adjustment of the distance of the outer edge of the aperture relative to 
the particle size retention is made in the same manner as that of the 
thickness of the filter paper. Accordingly, as the particle size retention 
value increases, the outer edge distance from the target area increases, 
and as the particle size retention value decreases, the outer edge 
distance from the target area decreases. 
Related to particle size retention is the flow rate or linear wicking of 
the filter paper. This value can be defined in a variety of ways depending 
on the manufacturer of the filter paper. Preferably, the flow rate (which 
can be defined in terms of the time necessary for distilled water to rise 
a specified distance on the filter paper) is between about 0.3 cm/minute 
and about 0.9 cm/minute. Most preferably, the flow rate is about 0.6 
cm/minute. The flow rate value is of import in that diffusion of the 
sample is related to the flow rate of the filter paper. Thus, as flow rate 
increases, the outer edge distance from the target area increases, and as 
the flow rate decreases, the outer edge distance from the target area 
decreases. 
ADVANTAGES OF THE INVENTION 
The advantages derived from the present invention include the placement of 
a consistent quantity of sample applied in a consistent manner to a 
consistent location on test sheet 101 such that addition of a developing 
solution close to but not directly into the diffusion area allows the 
developer to migrate through the diffusion area, carrying the resultant 
color (e.g. blue when guaiac treated paper is utilized) away from the dark 
background of the diffused region, thus increasing and enhancing the 
readability of the reaction. These advantages are derived from locating 
the aperture relative to the indicating means. Furthermore, because the 
patient is instructed to completely fill the aperture, variations in the 
amount of sample added to a specimen slide are avoided as well as the 
aforementioned concerns associated with such variations. Additionally, 
because specimen slide 100 does not yield any additional sub-parts or 
components which may require separate disposal, the entire slide can be 
disposed upon completion of development, thereby reducing the potential 
for improper disposal of a clinical material. 
While the present invention has been set forth in considerable detail, the 
invention disclosed herein is not to be limited to the detailed 
description, but is to be afforded the full scope of the appended claims 
and all equivalents thereto.