5/24/05njm

**Q. Is it standard of care to obtain a 2nd ultrasound on low risk
patients for a fetal survey?**

A. It is reasonable to obtain one US. The optimal timing is at 16 to 20
weeks of gestation

First point....sorry that was a bit of a trick question.

There is not good evidence to support routine use of ultrasound for a
'fetal survey', per se. On the other hand, there is evidence for one
ultrasound to establish excellent dating parameters, as that can save
fetal lives, due to a reduction of post-datism.

At our facility our one 'screening' US was started because we wanted to
establish dating in all our patients initially for geographic / logistic
reasons.... and then later after the Cochrane Review came out we
continued it to decrease the possible fetal death related to post dates.

So what started as a 'dating' ultrasound started getting done at a time
that was also good for a 'fetal survey' (16-18 weeks).....and somehow
now staff thought that a 'fetal survey' was indicated for all patients.

As our system tries to deal with the increasingly heavy load of
ultrasound exams our patients get, both indicated and not so indicated,
I think the following discussion may help us get back to our original
thinking and perhaps 'right size' our overall usage of US in pregnancy.

Somehow that one US 'dating' US morphed into a 'fetal survey' ultrasound
over many years of mis-interpretation, e.g., if one gets an accurate
dating US early in pregnancy for size not equal to dates,  there is not
data to not support the use of a second US for a 'fetal survey', per se.

**Background**

#1 The evidence for the value of one ultrasound at 16 - 20 weeks is
based in its ability to predict post-term pregnancy and its subsequent
morbidity and mortality.

The **Cochrane Library** reviews on this topic state:

"Routine ultrasound in early pregnancy appears to enable better
gestational age assessment, earlier detection of multiple pregnancies
and earlier detection of clinically unsuspected fetal malformation at a
time when termination of pregnancy is possible."

and

"Routine early pregnancy ultrasound examination and subsequent
adjustment of delivery date appear to reduce the incidence of post-term
pregnancy. Routine induction of labour after 41 weeks gestation appears
to reduce perinatal mortality."

#2 On the other hand, repeat ultrasound examinations do not confer
benefit on mother or baby.

The Cochrane Library review on this topic states:

"Based on existing evidence, routine late pregnancy ultrasound in low
risk or unselected populations does not confer benefit on mother or
baby. There is a lack of data about the potential psychological effects
of routine ultrasound in late pregnancy, and the effects on both short
and long term neonatal and childhood outcome. Placental grading in the
third trimester may be valuable, but whether reported results are
reproducible remains to be seen, and future research of late pregnancy
ultrasound should include evaluation of placental textural assessment."

#3

This one ultrasound may be especially important in Indian Country, due
the logistics in which many of our patients deliver.

Here are excerpts from other benchmark resources

**Ultrasonography in pregnancy. ACOG Practice Bulletin No. 58**

**Conclusions**

-   Ultrasound examination is an accurate method of determining
    gestational age, fetal number, viability, and placental location.
    Gestational age is most accurately determined in the first half of
    pregnancy.

-   The ability of ultrasonography to diagnose major fetal anomalies is
    well established.

-   The diagnosis of fetal growth abnormalities with ultrasonography is
    not precise.

-   Ultrasonography is safe for the fetus when used appropriately.

-   Specific indications are the best basis for the use of
    ultrasonography in pregnancy.

-   The optimal timing for a single ultrasound examination in the
    absence of specific indications for a first-trimester examination is
    at 16--20 weeks of gestation.

-   

**Summary of Recommendations**

***The following recommendation is based on limited or inconsistent
scientific evidence (Level B):***

-   Serial ultrasonograms to determine the rate of growth should be
    obtained approximately every 2--4 weeks.

***The following recommendations are based primarily on consensus and
expert opinion (Level C):***

-   Casual use of ultrasonography, especially during pregnancy, should
    be avoided.

-   Before an ultrasound examination is performed, patients should be
    counseled about the limitations of ultrasonography for diagnosis.

**UpToDate**

**RECOMMENDATIONS** --- If one screening ultrasound examination is
performed, the optimal timing is at 16 to 20 weeks of gestation

**First trimester** --- Based upon the discussion above, routine early
ultrasound is beneficial in an unselected population because of better
estimation of gestational age resulting in significantly reduced
frequency of labor induction for postterm pregnancy and use of tocolysis
for suspected preterm labor.

In addition, first trimester ultrasound examination can lead to earlier
detection of clinically unsuspected fetal malformations and earlier
detection of multiple pregnancy. These effects have not been shown to
improve ultimate fetal outcome, although studies have lacked power to
assess for secondary outcomes. Improvements in technology, increasing
experience, and refinements in visualization should make the detection
of anomalies in the first trimester more efficient at a time when
termination of pregnancy is possible and private.

**Second trimester** --- The large number of trials addressing
ultrasound screening in the second trimester of pregnancy primarily
focused upon detection of anomalies. The value (ie, utility) that
individual patients place on birth, or avoidance of birth, of a child
with an unsuspected anomaly needs to be incorporated into any
cost-benefit equation of this issue, but is not routinely assessed. The
Eurofetus trial likely approaches the most accurate sensitivity rates
for ultrasound in the detection of anomalies (approximately 50 to 70
percent).

Ultrasound in the second trimester is also effective when used to
establish EDD.

Overall, these data suggest that is both ethical and cost-effective to
offer routine screening in the second trimester for detection of fetal
anomalies and that the ultrasound examination should be carried out by
experienced and thorough practitioners. The examination should be
performed at a gestational age that allows for good visualization of
anatomy, and thus will have a high yield for anomalies. At the same
time, it should be done at a gestational age that is early enough to
allow completion of prenatal diagnostic procedures (eg, fetal karyotype,
additional imaging studies) while legal termination of pregnancy is
possible, if desired. The optimal timing of second trimester ultrasound
screening for fetal anomalies seems to be from 16 to 20 weeks.

**Third trimester** --- The currently available data does not support
the routine use of ultrasound in the third trimester to screen low risk
women.

**Summary**

In Indian Country it is reasonable to obtain one ultrasound at 16- 20
weeks. This may be especially important due the logistics in which many
of our patients deliver. Other ultrasound studies should be obtained for
specific obstetric indications.

**[References:]{.underline}**

Ultrasonography in pregnancy. ACOG Practice Bulletin No. 58. American
College of Obstetricians and Gynecologists. Obstet Gynecol
2004;104:1449--58.

**Non-ACOG Members**

<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=15572512>

**ACOG members**

<http://www.acog.org/publications/educational_bulletins/pb058.cfm>

Bricker L, Neilson JP. Routine ultrasound in late pregnancy (after 24
weeks gestation). *The Cochrane Database of Systematic Reviews* 2000,
Issue 1. Art. No.: CD001451. DOI: 10.1002/14651858.CD001451

Crowley P. Interventions for preventing or improving the outcome of
delivery at or beyond term. *The Cochrane Database of Systematic
Reviews* 1997, Issue 1. Art. No.: CD000170. DOI:
10.1002/14651858.CD000170.

Neilson JP. Ultrasound for fetal assessment in early pregnancy. *The
Cochrane Database of Systematic Reviews* 1998, Issue 4. Art. No.:
CD000182. DOI: 10.1002/14651858.CD000182.

**Routine prenatal ultrasonography as a screening tool: UpToDate**

<http://www.uptodateonline.com/application/topic.asp?file=antenatl/18078&type=A&selectedTitle=3~62>

**Indications for diagnostic obstetrical ultrasound examination:
UpToDate**

<http://www.uptodateonline.com/application/topic.asp?file=antenatl/7451&type=A&selectedTitle=1~62>

**Assessment of gestational age: UpToDate**

<http://www.uptodateonline.com/application/topic.asp?file=neonatol/8161&type=A&selectedTitle=14~62>

**Physics and safety of diagnostic ultrasound in obstetrics and
gynecology: UpToDate**

<http://www.uptodateonline.com/application/topic.asp?file=antenatl/15779&type=A&selectedTitle=17~62>

**Technique for ultrasound examination in obstetrics and gynecology:
UpToDate**

<http://www.uptodateonline.com/application/topic.asp?file=antenatl/14673&type=A&selectedTitle=12~62>

**Cochrane Library**

<http://www.update-software.com/cochrane/abstract.htm>

**Ultrasound for fetal assessment in early pregnancy**

**Background:** Advantages of early pregnancy ultrasound screening are
thought to be more accurate calculation of gestational age, earlier
identification of multiple pregnancies, and diagnosis of non-viable
pregnancies and certain fetal malformations.

**Objectives:** The objective of this review was to assess the use of
routine (screening) ultrasound compared with the selective use of
ultrasound in early pregnancy (ie before 24 weeks).

**Search strategy:** The Cochrane Pregnancy and Childbirth Group trials
register and the Cochrane Controlled Trials Register (up to June 2001)
were searched.

**Selection criteria:** Adequately controlled trials of routine
ultrasound imaging in early pregnancy.

**Data collection and analysis:** One reviewer assessed trial quality
and extracted data. Study authors were contacted for additional
information.

**Main results:** Nine trials were included. The quality of the trials
was generally good. Routine ultrasound examination was associated with
earlier detection of multiple pregnancies (twins undiagnosed at 26
weeks, odds ratio 0.08, 95% confidence interval 0.04 to 0.16) and
reduced rates of induction of labour for post-term pregnancy (odds ratio
0.61, 95% confidence interval 0.52 to 0.72). There were no differences
detected for substantive clinical outcomes such as perinatal mortality
(odds ratio 0.86, 95% confidence interval 0.67 to 1.12). Where detection
of fetal abnormality was a specific aim of the examination, the number
of terminations of pregnancy for fetal anomaly increased.

**Authors\' conclusions:** Routine ultrasound in early pregnancy appears
to enable better gestational age assessment, earlier detection of
multiple pregnancies and earlier detection of clinically unsuspected
fetal malformation at a time when termination of pregnancy is possible.
However, the benefits for other substantive outcomes are less clear.

**Citation:** Neilson JP. Ultrasound for fetal assessment in early
pregnancy. *The Cochrane Database of Systematic Reviews* 1998, Issue 4.
Art. No.: CD000182. DOI: 10.1002/14651858.CD000182.

**Routine ultrasound in late pregnancy (after 24 weeks gestation).**

**Background:** Diagnostic ultrasound is used selectively in late
pregnancy where there are specific clinical indications. However, the
value of routine late pregnancy ultrasound screening in unselected
populations is controversial. The rationale for such screening would be
the detection of clinical conditions which place the fetus or mother at
high risk, which would not necessarily have been detected by other means
such as clinical examination, and for which subsequent management would
improve perinatal outcome.

**Objectives:** To assess the effects on obstetric practice and
pregnancy outcome of routine late pregnancy ultrasound, defined as
greater than 24 weeks gestation, in women with either unselected or low
risk pregnancies.

**Search strategy:** The Cochrane Pregnancy and Childbirth Group
Specialised Register of Controlled Trials and the Cochrane Controlled
Trials Register were searched.

**Selection criteria:** All acceptably controlled trials of routine
ultrasound in late pregnancy (defined as after 24 weeks).

**Data collection and analysis:** The principal reviewer assessed trial
quality and extracted data, under supervision of the co-reviewer.

**Main results:** Seven trials recruiting 25,036 women were included.
The quality of trials overall was satisfactory. There was no difference
in antenatal, obstetric and neonatal intervention or morbidity in
screened versus control groups. Routine late pregnancy ultrasound was
not associated with improvements in overall perinatal mortality.
Placental grading as an adjunct to third trimester examination scan was
associated with a significant reduction in the stillbirth rate in the
one trial that assessed it. There is a lack of data with regard to long
term substantive outcomes such as neurodevelopment. There is a lack of
data on maternal psychological effects.

**Authors\' conclusions:** Based on existing evidence, routine late
pregnancy ultrasound in low risk or unselected populations does not
confer benefit on mother or baby. There is a lack of data about the
potential psychological effects of routine ultrasound in late pregnancy,
and the effects on both short and long term neonatal and childhood
outcome. Placental grading in the third trimester may be valuable, but
whether reported results are reproducible remains to be seen, and future
research of late pregnancy ultrasound should include evaluation of
placental textural assessment.

**Citation:** Bricker L, Neilson JP. Routine ultrasound in late
pregnancy (after 24 weeks gestation). *The Cochrane Database of
Systematic Reviews* 2000, Issue 1. Art. No.: CD001451. DOI:
10.1002/14651858.CD001451.

**Interventions for preventing or improving the outcome of delivery at
or beyond term.**

**Background:** Perinatal mortality and morbidity is increased in
pregnancies of more than 42 weeks that are otherwise low risk.

**Objectives:** The objective of this review was to assess the effects
of interventions aimed at either reducing the incidence or improving the
outcome of post-term pregnancy.

**Search strategy:** The Cochrane Pregnancy and Childbirth Group trials
register was searched.

**Selection criteria:** Randomised and quasi-randomised trials of
interventions involving the intention to induce labour at a specified
gestational age.

**Data collection and analysis:** Eligibility and trial quality were
assessed by one reviewer. Study authors were contacted for additional
information.

**Main results:** Twenty-six trials of variable quality were included.
There were four trials of routine early pregnancy ultrasound, two of
nipple stimulation, nineteen of routine versus selective induction of
labour and one of antenatal fetal monitoring. Routine early pregnancy
ultrasound reduced the incidence of post-term pregnancy (odds ratio
0.68, 95% confidence interval 0.57 to 0.82). Breast and nipple
stimulation at term did not affect the incidence of post-term pregnancy
(odds ratio 0.52, 95% confidence interval 0.28 to 0.96). Routine
induction of labour reduced perinatal mortality (odds ratio 0.20, 95%
confidence interval 0.06 to 0.70). This benefit is due to the effect of
induction of labour after 41 weeks. Routine induction of labour had no
effect on caesarean section.

**Authors\' conclusions:** Routine early pregnancy ultrasound
examination and subsequent adjustment of delivery date appear to reduce
the incidence of post-term pregnancy. Routine induction of labour after
41 weeks gestation appears to reduce perinatal mortality. There is not
enough evidence to evaluate the effects of breast and nipple
stimulation, or tests of fetal wellbeing.(This abstract has been
prepared centrally.)

**Citation:** Crowley P. Interventions for preventing or improving the
outcome of delivery at or beyond term. *The Cochrane Database of
Systematic Reviews* 1997, Issue 1. Art. No.: CD000170. DOI:
10.1002/14651858.CD000170.