Diagnostic ultrasound ( PDFDrive )

CHAPTER 30 The First Trimester 1063
FSH or LH or abnormal patterns of secretion, or a decreased
response of the endometrium to progesterone.
Angiogenesis of the corpus luteum may be needed for the
regulation of progesterone production. Kupesic et al. 70 found
that the resistive index (RI) in intraovarian arteries in normal
nongravid women dropped below 0.47 in the luteal phase
compared to a group with luteal phase defect who had a high
resistance throughout the menstrual cycle, with RI always above
0.50. hey suggest that Doppler sonography may predict functional
capacity of the corpus luteum, at least in the nongravid
state. Blumenfeld and Ruach 69 were successful in treating luteal
phase defect in a group undergoing ovulation induction and in
patients with previous abortions, using hCG administration twice
weekly in the sixth and tenth weeks. his reduced the rate of
miscarriage from 49% to 17.8% (P < .01).
Currently, as medical management for a failed pregnancy
may include intervention with misoprostol that may harm a
potentially viable pregnancy, a false positive diagnosis of early
pregnancy failure can lead to negative consequences. his has
led to a philosophy espoused by the Society of Radiologists in
Ultrasound of using conservative criteria on ultrasound for early
pregnancy failure that would eliminate a false positive result. 5,27
Early pregnancy failure may not always be able to be diagnosed
or excluded on the basis of a single ultrasound, and follow-up
studies may be necessary for conclusive diagnosis.
Diagnostic Findings of Early
Pregnancy Failure
Diagnostic Findings of Early
Pregnancy Failure
CRL of 7 mm without a heartbeat
MSD of 25 mm without an embryonic pole
Crown-Rump Length 7 mm or Greater and
No Heartbeat
In patients with a sonographically demonstrable embryo, no
cardiac activity is one of the most important factors in predicting
pregnancy outcome. he absence of cardiac activity does not
necessarily indicate embryonic demise, however, because TVS
can identify a normal, very early embryo without cardiac
activity.
Many studies have demonstrated that cardiac activity is
expected when CRL is greater than 5 mm. Levi et al. 3 reviewed
a series of 96 patients with CRL of less than 5 mm to assess the
predictive value of the presence or absence of cardiac activity
using TVS. Of 71 patients available for follow-up, 46 embryos
had cardiac activity, 35 progressed to at least the late second
trimester, and 11 ended as irst-trimester demise. Of the 25
embryos without demonstrable cardiac activity, 5 (20%) were
normal and 20 (80%) ended as irst-trimester embryonic deaths.
Of the ive normal embryos without demonstrable cardiac activity
on initial TVS, three had initial CRL of less than 1.9 mm. Standard
embryology texts indicate that the embryonic heart begins to
beat at the beginning of the sixth week, when the CRL is 1.5 to
3 mm. hus it is not surprising that cardiac activity may or may
not be identiied in normal embryos with CRL less than 2 mm.
In the study by Levi et al., initial TVS assessment failed to identify
cardiac activity in 2 of 25 normal embryos with CRL of 2 to
4 mm. TVS enabled correct identiication of cardiac activity in
100% of normal embryos with CRL of 4 to 4.9 mm. 3 Pennell
et al. 71 found that 16 of 18 embryos with CRL less than 5 mm
had no cardiac activity on initial TVS assessment but demonstrated
cardiac activity on follow-up TVS. Cardiac motion was
seen on TVS in all pregnancies with CRL greater than 5 mm.
he combination of vaginal bleeding and absent cardiac activity
in embryos of CRL less than 5 mm on TVS is associated with a
very poor prognosis. Aziz et al. 72 reviewed outcomes in embryos
of CRL of 5 mm or less with absent cardiac activity on TVS, in
women presenting with vaginal bleeding; all resulted in pregnancy
failure.
Before making a diagnosis of embryonic demise, it is critical
to ensure that the examination is of high quality, performed with
modern equipment and an appropriate transducer frequency,
and that the entire embryo is visualized. A high frame rate must
be used, and the frame-averaging mode must be turned of. If
there is any doubt in the diagnosis, follow-up examination should
be performed. here is interobserver variability in measurement,
even by experienced sonographers. In a prospective cross-sectional
study on 1060 women, Abdullah et al. demonstrated that changing
the CRL cutof to greater than 7 mm would minimize the risk
of a false positive diagnosis of miscarriage. A generous cutof
ensures that a desired pregnancy would not be mistakenly terminated
by the administration of medication for chemical
miscarriage or dilation and curettage to remove products
of conception 4,5 (Fig. 30.18, Video 30.2). It is also imperative
that transmitted maternal pulsations are not mistaken for
embryonic cardiac pulsations, especially when evaluating a static
M-mode image to verify embryonic cardiac activity (Figs. 30.18B
and 30.19).
Gestational Sac Mean Sac Diameter 25 mm or
Greater and No Embryo
In many patients the embryo is not visualized on the initial
sonogram, and the diagnosis of pregnancy failure cannot be
made on the basis of lack of cardiac activity. In these patients
the diagnosis of pregnancy failure may be made based on gestational
sac characteristics. he most reliable indicator of abnormal
outcome based on gestational sac features is abnormal size. 2,42
Using TVS, an MSD of 8 mm or more without a demonstrable
yolk sac, or 16 mm with no demonstrable embryo, are
not typical and are suggestive of pregnancy failure. 5,43 However,
recent studies have documented gestational sacs up to 21 mm
with initially no visible embryos that went on to be viable
pregnancies. 4 Most authors allow a few millimeters of leeway
in MSD measurements as a margin of error, and many do not
use the absent yolk sac as a sign of pregnancy failure. his is
partly due to interobserver variability in measurements. Given
these variables, the Society of Radiologists in Ultrasound recently
advocated diagnosing early pregnancy failure by gestational sac
size only for sacs with MSD of 25 mm or greater with no embryo 5
(Fig. 30.20).