Diagnostic ultrasound ( PDFDrive )

CHAPTER 30 The First Trimester 1065
A
B
FIG. 30.20 TVS Findings Diagnostic of Early Pregnancy Failure With Large, Empty Sac. (A) Transverse and (B) sagittal images of an empty
gestational sac with MSD (calipers) greater than 25 mm. No yolk sac or embryonic pole is visualized.
TABLE 30.2 Worrisome Findings for Early Pregnancy Failure
Finding
Embryo with CRL < 7 mm
and no heartbeat
Gestational sac with MSD
16-24 mm and no embryo
Gestational sac appearance
Small MSD in relationship
to CRL
Abnormal amnion size
Yolk sac > 6 mm
Calciied yolk sac
Embryonic bradycardia
Large subchorionic
hemorrhage
Comment
Embryo 2-6 mm without cardiac activity is a worrisome inding. Follow-up is needed to
assess for cardiac activity in 1 week to ensure 100% speciicity in diagnosis of
miscarriage.
Embryo is typically seen by the time the MSD is 16 mm. Follow-up in 10-14 days is needed
to ensure 100% speciicity in diagnosis of miscarriage.
Irregular shape of sac, low position of sac, and weak decidual reaction are associated with
miscarriage, but the size of the embryo and presence or absence of cardiac activity
guides the diagnosis of miscarriage.
Low luid is associated with poor outcome. If MSD-CRL < 5, follow-up is recommended.
Expanded amnion or empty amnion as evaluated by an experienced sonologist is diagnostic
of miscarriage. If any uncertainty is present, then follow-up should be obtained.
Findings are associated with miscarriage, but the size of the embryo and presence or
absence of cardiac activity guides the diagnosis.
Heart rate (HR) < 100 may be seen with 1- to 2-mm embryo and be a normal inding. In
general, when HR is <100, follow-up is recommended.
Large hemorrhage is associated with miscarriage, but the size of the embryo and presence
or absence of cardiac activity guides the diagnosis of miscarriage.
useful information in assessing the normal development in serial
examinations. With an expected growth rate of 1.1 mm/day, one
should see an appropriate increase in sac size and, if normal, the
appearance of a yolk sac or an embryo. If the growth is less than
expected, it becomes more suggestive of early pregnancy failure.
On follow-up imaging, absence of an embryo with a heartbeat
7 to 13 days ater a scan showing a gestational sac without a
yolk sac or 7 to 10 days ater a scan showing a gestational sac
with a yolk sac remains suspicious. Given the remaining small
chance that such pregnancies may still progress, longer time
intervals between examinations are necessary for conident
diagnosis. 5
Gestational Sac Appearance
he following gestational sac criteria are not reliable in isolation
but indicate a pregnancy at increased risk for early failure:
distorted gestational sac shape, thin trophoblastic reaction
(<2 mm), weakly echogenic trophoblast, and abnormally low
position of the gestational sac within the endometrial cavity 42
(Fig. 30.21).
A “chorionic bump,” a focal irregular convexity or bulge in
the surrounding choriodecidual reaction into the gestational sac,
is associated with a guarded prognosis with a live birth rate for
these pregnancies of less than 50%. he bulge likely represents
a small hematoma. 74