Diagnostic ultrasound ( PDFDrive )

CHAPTER 30 The First Trimester 1071
A
B
C
FIG. 30.29 Ruptured Ectopic Pregnancy. A 28-year-old woman with
pelvic pain at 8 weeks’ gestation. (A) TAS of the left upper quadrant
demonstrates free luid adjacent to the splenorenal fossa (arrow). (B) Sagittal
and (C) transverse TVS scans show an oval intrauterine luid collection
illed with low-level echoes. No yolk sac or embryo is seen. This represents
a pseudogestational sac. Free luid is seen anterior and posterior to
the uterus. The ectopic pregnancy was not visualized but was removed
laparoscopically.
sensation that brought the patient to hospital initially. Pain can
also be felt with other inlammatory or expanding masses, such
as a hemorrhagic corpus luteum. he pelvis and cul-de-sac should
be examined for luid.
TVS ultrasound may miss an ectopic pregnancy located high
out of the ield of view of the probe or when a pelvic mass such
as a ibroid or bowel gas is located between the vagina and the
adnexa. 104-106 In 5% of cases, indings may be present that only
TAS can identify 107 (see Fig. 30.28).
Heterotopic Gestation
If a normal IUP is identiied, the likelihood of ectopic pregnancy
is drastically reduced. In the presence of an IUP, the risk of
coexistent ectopic pregnancy (heterotopic gestation) lies between
1 in 4000 and 1 in 7000. 100,108 However, even in the presence of
an IUP, evaluation of the adnexa should be performed to screen
for a possible coexistent ectopic pregnancy, especially in women
who present with adnexal pain and women with a history of
assisted reproduction techniques such as IVF. 109 he risk for
heterotopic pregnancy may be as high as 1% to 3% in women
undergoing ovulation induction 110 (Fig. 30.30).
Serum β-hCG Levels
Serum β-hCG levels play an important adjunctive role in the
early diagnosis of ectopic pregnancy. A negative β-hCG level
excludes the possibility of live pregnancy in a woman presenting
with pain whereas a negative ultrasound does not. As previously
stated, the WHO recommends that the hird IS and the identical
Fourth IS should be used for calibration of immunoassays. 37
In general, we expect to visualize a gestational sac when the
β-hCG level is greater than 2000 mIU/mL (IRP). Discriminatory
levels such as this can be used to guide management
but cannot be used as absolute indicators that the absence of
a sonographically demonstrable gestation sac with this level
of β-hCG is abnormal. A 2013 study by Connolly found that
of 366 patients with irst-trimester pain and bleeding, whose
pregnancies ultimately were shown to be viable, a hCG level of
3510 mIU/mL was needed for a gestational sac to be seen 99%
of the time. 111 Serial β-hCG measurements are usually more
helpful than a single measurement in identifying abnormal from
normal pregnancy, and ultrasound may document important
diagnostic features regardless of the β-hCG value. 5 he β-hCG
level in a normal pregnancy has a doubling time of approximately
2 days, whereas patients with a failed or failing gestation have a
falling β-hCG level. Patients with ectopic pregnancy usually have
a slower increase in β-hCG levels, although they occasionally
show patterns similar to a normal pregnancy or spontaneous
abortion.
Speciic Sonographic Findings
he most speciic sonographic sign of ectopic pregnancy is
documentation of a live embryo in an extrauterine location (Fig.