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Chapter 30 ■ The First Trimester 1097
A
ys
a
e
B
C
FIGURE 30-31. Intrauterine embryonic death with yolk sac calcification. A, Transvaginal color Doppler ultrasound
scan of a pregnancy at
appearing yolk sac (arrow). B, Repeat scan 5 days later shows no change in the size of the embryo (calipers) and a dense yolk sac (arrow)
with faint distal shadowing. C, In a different pregnancy, transvaginal sagittal scan shows calcified yolk sac (ys). No cardiac activity was
identified in embryo with crown-rump length of 18 mm. a, Amnion; e, embryo.
1
6
weeks’ menstrual age (CRL, 6.5 mm) shows an embryo with no cardiac activity (no color), and a normal-
2
In a group of patients with vaginal bleeding at 10
to 20 weeks’ gestation, identification of a subchorionic
hemorrhage was associated with a 50% fetal loss rate.
In a retrospective study of 516 patients with first-trimester bleeding, Bennett et al.
78
found an overall pregnancy
77
loss rate of 9.3%. This increases with increasing maternal
age and decreasing gestational age. For women over age
35, the rate is 13.8% (vs. 7.3 for those ≤35), and for
those presenting at or before 8 weeks, it is 13.7% (vs.
only 5.9% for those later in gestation). The most important predictor for pregnancy loss was the presence of a
large subchorionic hemorrhage.
78
The small or medium-
sized hemorrhages (i.e., ≤50% the sac circumference)
had a miscarriage rate of 9%, versus 18.8% for the larger
subchorionic hemorrhages.
Ball et al.
76
found an increased risk of miscarriage (odds
ratio [OR], 2.8), stillbirth (OR, 4.5), abruptio placentae
(OR, 11.2), and preterm labor (OR, 2.6) when women
with hemorrhaging were compared with controls without
subchorionic hemorrhage or bleeding. The presence of
bleeding alone also increased the risk of miscarriage.
Abu-Yousef et al.
79
followed 21 cases of subchorionic
hematoma (8-19 weeks’ gestation), and 17 had vaginal
bleeding; 71% had an unfavorable outcome of spontaneous abortion or prematurity. They found significant correlation between pregnancy outcome and hematoma
size, severity of bleeding, and presence of pain, but no
correlation between outcome and elevation of the placental edge.
Pedersen and Mantoni
80
studied 342 pregnant women
from 9 to 20 weeks’ gestation presenting with vaginal
bleeding and found subchorionic hematomas in 18%,
averaging 20 cc (range, 2-150) in size. Although most
studies show an association between subchorionic
1098 PART IV ■ Obstetric Sonography
hemorrhage and abnormal outcome, this study found no
difference in the rate of miscarriage (10%) or premature
delivery (11%) between the patients with and without
subchorionic hematomas.
Doppler Ultrasound Assessment
A
B
FIGURE 30-32. Echogenic material within yolk sac.
A, Single live embryo at 7 weeks’ gestational age with echogenic
material within the yolk sac (ys) next to a live embryo. B, One
week later the yolk sac looks normal, and the pregnancy continued
uneventfully.
*
FIGURE 30-33. Moderate subchorionic bleed. Sagit-
tal transvaginal scan of an 8-week gestation with no spotting. The
moderate subchorionic bleed (*) is seen adjacent to the gestational
sac. The live embryo was not in the field of view. The bleed
resolved and pregnancy continued uneventfully.
In the normal pregnancy, maternal peripheral vascular
resistance decreases as early as 5 weeks’ gestation.
81
Uterine arterial flow resistance decreases progressively
after implantation but increases in women with preeclampsia or IUGR.
82
Normally, before 12 weeks’ gestation, no flow is detectable within the trophoblastic ring,
consisting of the intervillous space, chorionic villi, and
their fetal vessels.
arterial flow is present normally in the decidual spiral
arteries.
7
83
As noted previously, low-resistance
Controversy surrounds whether Doppler sonography
of the uterine or spiral arteries is useful in predicting
pregnancy outcome. Extravillous trophoblastic cells
invade the decidual spiral arteries. Inadequate trophoblastic invasion of the spiral arteries may be seen in early
pregnancy failure and may be associated with increased
resistance to flow in the spiral arteries. Jaffe et al.
83
suggest that an abnormal RI (>0.55) in the decidual
spiral arteries and active arterial blood flow in the intervillous space may be associated with an increased incidence of early pregnancy failure. They speculate that
abnormal, high-pressure blood flow in the spiral arteries
may result in significantly increased pressure to the
immature villi, causing detachment of the early villi and
subsequent miscarriage. Others have not found Doppler
ultrasound to be predictive of pregnancy outcome.
84,85
Nakatsuka et al.86 found that the pulsatility index
(PI) of the uterine artery in two groups (N = 52) of
women at 4 to 5 weeks’ gestation was significantly higher
in the group with recurrent pregnancy loss (≥2 consecutive losses), as well as in women with elevated antinuclear
or antiphospholipid antibodies, compared to the control
group. In the group with recurrent loss, uterine artery
PI was significantly higher even in those without elevated
antibodies. The authors strongly suggest that uterine
artery PI is an independent index for recurrent pregnancy loss. The mean values of PI for the controls were
2.20 ± 0.52, and for the recurrent loss group, 2.5 ± 0.52.
Those with elevated antibodies and recurrent loss had PI
of 3.08 ± 0.61 or higher. The study outcome was not
entirely clear because women with recurrent losses were
treated with aspirin, heparin, or both in early pregnancy,
a result of the current belief that coagulopathy and vascular dysfunction may impair uterine perfusion and
result in pregnancy loss. Leible et al.
87
studied the uterine
artery PI in 318 consecutive early pregnancies from 6 to
12 weeks and found that a significant difference between
the two uterine arteries was strongly associated with
pregnancy failure before 20 weeks, likely because of
uterine ischemia.
Chapter 30 ■ The First Trimester 1099
*
*
A B
FIGURE 30-34. Small subchorionic bleed. A, Sagittal transvaginal scan of a 10-week gestation with a small subchorionic hemor-
rhage (*) elevating the posterior placental edge in the lower uterine segment. B, Transverse scan of the small bleed. C, Sagittal transvaginal
color Doppler ultrasound showing no flow in the subchorionic bleed.
Amniotic Sac Abnormalities
A large amniotic sac compared to the CRL is predictive of
abnormal outcome. Horrow
88
demonstrated that the dif-
ference between the CRL and the amniotic sac diameter
2.0 mm in normal embryos, but 8.6 ± 3.8 mm in
is 1.1 ±
abnormal pregnancies. In abnormal early pregnancies the
chorionic cavity remained appropriate in size relative to
the embryonic CRL, indicating that the increased differ-
C
91% (201/221) miscarried within 9 days (range, 1-32);
54% were complete within 7 days, 83% within 14 days,
and 89% within 21 days. There was no correlation
between the presence or absence of a gestational sac and
failed medical management. Twenty women required
surgery, with 19 elective and uneventful and one
emergent with excessive bleeding, pain, fever, and
leukocytosis.
*
ence in CRL compared to amnion diameter is caused by
enlargement of the amnion rather than a small embryo.
This finding is especially useful in early embryos before
visualization of cardiac activity. As with other predictors
of abnormal outcome, patients with abnormal amnion
diameters should be considered at increased risk and
should have a follow-up ultrasound examination.
Retained Products of Conception
Retained products of conception (RPOC) can have a
spectrum of sonographic appearances, from a seemingly
empty uterus to a large, echogenic mass of tissue filling
the endometrial canal. We have found that the presence
of focal increased vascularity is of great importance in
Termination of Early
Pregnancy Failure
Termination may be surgical, medical, or expectant
management. Surgical termination is generally by
suction dilation and curettage (D&C) of the intrauterine
contents under local or light general anesthesia. Medical
termination,
using mifepristone (600 mg) then miso-
prostol (400 µg) orally 2 days later, was found to be more
acceptable to women than surgical intervention; the
majority would repeat this management or would recommend it to others.
89
Later regimens used misoprostol
vaginally rather than orally with greater success. In 220
consecutive pregnancy failures using repeated doses of
mifepristone and misoprostol, Wagaarachchi et al.
defined success as complete uterine evacuation within 3
90
The overall success rate was 84%. Success in
days.
90
symptomatic women was 80%, versus 94% in asymptomatic women.
Expectant management of incomplete first-trimester
miscarriage was tested by Luise et al.,
91
who found that
distinguishing between blood clots and RPOC. There
can be a single vessel or a large group of vessels, either
superficially in the myometrium or extending deep
within it. The vascularity shows high-velocity flow up to
160 cm/sec with a mass of vessels. This can appear very
dramatic on the scan and, because of the high flow, can
raise concern about performing D&C. We have seen this
as a common finding, however, with a surprising lack
of any untoward bleeding during or after the surgery
(Fig. 30-35).
ECTOPIC PREGNANCY
Ectopic pregnancy remains one of the leading causes of
maternal death in the United States. It accounts for
1.4% of all pregnancies and approximately 15% of
maternal deaths. Although the incidence of ectopic pregnancy is increasing, the mortality has declined to less
than 1 in 1000 cases compared with 3.5 in 1000 in
92,93
1970.
The increased incidence is likely caused by
1100 PART IV ■ Obstetric Sonography
A
C
FIGURE 30-35. Retained products of conception. A, Sagittal transvaginal scan of a 22-year-old woman who presented 5
weeks after a suction dilation and curettage (D&C) therapeutic abortion with vaginal bleeding. The endometrial canal is distended with
a 1.8 × 2.5–cm echogenic mass (arrows). B, Color Doppler ultrasound shows an area of marked increase in vascularity at the base of the
mass at its attachment to the myometrium. C, Sagittal transvaginal scan of a 28-year-old woman who had suction D&C for a therapeutic
abortion 6 weeks previously with vaginal bleeding. The myometrium in the body anteriorly was heterogeneous with increased echogenicity.
D,
Color spectral Doppler ultrasound shows increased vascularity with velocities of 1.3 m/sec.
increased prevalence of the risk factors as well as earlier
diagnosis, whereas heightened awareness and improved
diagnostic capabilities have decreased mortality.
Clinical Presentation
The classic clinical triad of pain, abnormal vaginal bleeding, and a palpable adnexal mass is only present in
approximately 45% of patients with ectopic pregnancy.
In addition, the positive predictive value of this triad is
only 14%. Other presenting signs and symptoms include
any combination of the classic triad, as well as amenorrhea, adnexal tenderness, and cervical motion tenderness. Schwartz and DiPietro
94
found that only 9% of
patients with clinically suspected ectopic pregnancy
actually had an ectopic pregnancy, whereas 17% had
symptomatic ovarian cysts, 13% had pelvic inflammatory disease, 8% had dysfunctional uterine bleeding, and
7% had spontaneous abortions. The clinical presentation
is thus nonspecific.
B
D
Importantly, even in the early 1990s, 5% of proven
ectopic pregnancies bypass all imaging and go directly to
surgery. In addition, even in retrospect, 8.7% of proven
ectopic pregnancies are sonographically normal.
The prevalence of ectopic pregnancy varies according
to the patient population and their inherent risk factors.
Nevertheless, all patients in the reproductive age group
are at risk. Factors that increase the risk of ectopic preg-
94
nancy include tubal abnormality preventing passage of
the zygote or resulting in delayed transit; previous tubal
pregnancy,
surgery; pelvic inflammatory disease; chlamydial salpingitis;
96,97
cesarean section, or tubal reconstructive
98
intrauterine contraceptive devices; and increased
age or parity.
There is a strong association between infertility and
ectopic pregnancy, likely because of the shared tubal
abnormalities in both conditions. The risk factors for
ectopic pregnancy are therefore present in patients who
undergo ovulation induction or in vitro fertilization
(IVF) and embryo transfer. The increased incidence of
95
Chapter 30 ■ The First Trimester 1101
RISK OF ECTOPIC PREGNANCY
Any tubal abnormality that may prevent passage of
zygote or result in delayed transit
Previous tubal pregnancy
History of tubal reconstructive surgery
Pelvic inflammatory disease
Intrauterine contraceptive device
Increased maternal age
Increased parity
Previous cesarean section
multiple pregnancies with ovulation induction and IVF
further increases the risk for both ectopic and hetero-
topic (coexistent intrauterine and ectopic) gestation.
The hydrostatic forces generated during embryo transfer
may also contribute to the increased risk.
99
The frequency of heterotopic pregnancy was originally estimated on a theoretic basis to be 1 in 30,000 pregnancies.
More recent data indicate that the rate is approximately
1 in 7000 pregnancies.
100,101
Sonographic Diagnosis
When women present with a positive pregnancy test or
a history suggestive of ectopic pregnancy (missed period,
pain, unprotected intercourse), it is critical to identify
the presence and location of the gestational sac. Pelvic
ultrasound and especially TVS must be the first line of
imaging investigation. TVS allows for a more detailed
evaluation of the endometrium, endometrial canal, and
adnexa than TAS. The imaging component must be
augmented by the clinical findings of tenderness elicited
by the transvaginal probe. Uterine tenderness is uncommon, but adnexal tenderness may be important in
leading to the ectopic site or less often to a ruptured or
leaking corpus luteum cyst. Focal uterine tenderness may
be seen with an IUP and a degenerating fibroid or in the
nongravid female from adenomyosis. Endometritis and
pelvic inflammatory disease are causes of a more generalized type of pelvic pain.
We begin the examination with TAS through a full
bladder, if possible, looking for a large or complex mass
that may be outside the range of the transvaginal probe.
The mass may be the extrauterine gestational sac or a
large hematoma. At the end of TAS, we always look for
free fluid in the hepatorenal space (Fig. 30-36; Video
30-4). This provides a sense of the degree of blood loss.
Although hemodynamically stable with a large volume
of fluid loss, the patient could decompensate rapidly.
Fluid seen in the hepatorenal space should impart a
greater sense of urgency to the surgeon.
We then perform a vaginal scan, assessing the uterus,
ovaries, and adnexal regions. If the ovary and tube cannot
be seen on one side, in a suspected ectopic pregnancy, a
helpful maneuver is to try and push the ovary down
toward the transvaginal probe by pressing firmly on the
anterior abdominal wall. The clinician must watch the
screen carefully for an echogenic mass or ectopic sac
as the adnexa is pushed downward and into the field
of view.
In early IUP, early pregnancy failure, or ectopic pregnancy, it is not always possible to identify the gestational
sac. Several nonspecific sonographic findings may help
in localization of the gestational sac. However, ectopic
pregnancy is generally excluded with the demonstration
of an IUP (which reduces the risk of coexistent ectopic
pregnancy to 1 in 7000) or is confirmed with demonstration of a live embryo in the adnexa.
Specific Findings
The earlier demonstration of an IUP is the most important contribution of TVS (vs. TAS) in the evaluation of
patients presenting with suspected ectopic pregnancy. In
a series of suspected ectopic pregnancies by Dashefsky et
102
all 19 normal intrauterine pregnancies were identi-
al.,
fied by TVS, versus only 11 of 19 for TAS. In addition,
TVS identified 7 of 16 abnormal IUPs, versus 3 of 16
for TAS.
102
As described earlier, the intradecidual sign and the
double-decidual sign can be used to identify an IUP
before visualization of the yolk sac or embryo. The
double-decidual sign must be distinguished from the
decidual cast or pseudogestational sac of ectopic pregnancy. A pseudosac is an intrauterine fluid collection
surrounded by a single decidual layer (Fig. 30-37),
as opposed to the two concentric rings of the doubledecidual sign. TVS allows for differentiation of the
decidua, which produces the pseudogestational sac, from
the choriodecidual reaction of the double-decidual sign
103
of IUP.
Doppler ultrasound and in particular color flow
Doppler imaging may further help distinguish a gestational sac from pseudosac. Peritrophoblastic flow is
high-velocity, low-resistance flow with low RI and PI.
Dillon et al.
104
studied a series of 40 patients with an
empty saclike structure in the uterus. They defined peritrophoblastic flow as a peak systolic frequency of 0.8 kHz
or greater (corresponding to 21 cm/sec with no angle
correction) and correctly classified 26 of 31 IUPs and 9
of 9 pseudogestational sacs.
104
When there is no sonographic evidence of an IUP,
the pregnant patient is more likely to harbor an extrauterine gestation. Because TVS allows for the earlier
identification of an IUP, it significantly increases the
accuracy of diagnosis in patients with suspected ectopic
gestation.
105
The sonographic demonstration of a live embryo in
the adnexa is specific for the diagnosis of ectopic pregnancy (Fig. 30-38). A live extrauterine embryo/fetus
has been detected with TVS in 17% to 28% of patients
1102 PART IV ■ Obstetric Sonography
*
U
A
B
*
C
FIGURE 30-36. Ruptured ectopic pregnancy with hemoperitoneum. A 35-year-old woman presented at 6 weeks’ gesta-
tion with right lower quadrant pain. A, Sagittal transvaginal scan shows echogenic material within the endometrial cavity but no gestational
sac. Blood clot is (*) seen around the uterus. B, Coronal transvaginal scan of the uterus (U) and a complex right adnexal mass with a sac
at its posterior aspect (arrow). C, Coronal color Doppler sonogram with no vascularity seen. D, Sagittal scan of the left upper abdomen
showing free fluid (*).
D
A B
FIGURE 30-37. Pseudogestational sac. A, Coronal transvaginal scan of a 33-year-old woman (G2P1) at 8 weeks with pelvic
pain. There is a rounded intrauterine sac filled with low-level echoes. No yolk sac or embryo is seen. There is a single echogenic ring
around the fluid (arrow). This is a fluid-filled endometrial canal, a decidual cast, or pseudogestational sac. B, Sagittal transvaginal scan
shows a large pseudogestational sac with echogenic debris. Note the acute angle at the lower end, uncommon in a gestational sac.
Chapter 30 ■ The First Trimester 1103
A
C
FIGURE 30-38. Live ectopic pregnancy. A 33-year-old woman presented with left lower quadrant pain at 9 weeks’ gestation.
A, Coronal transvaginal scan shows the empty endometrial cavity on the right and a gestational sac and embryo on the left. B, M-mode
image demonstrates a live embryo with cardiac activity at a rate of 173 beats/min. C,
D, In a different patient, coronal transvaginal scan of the right ovary with a corpus luteum cyst (c) and a gestational sac with a single live
embryo immediately adjacent (arrow).
106,107
with ectopic pregnancy,
versus only 10% with TAS.
Cardiac activity can be demonstrated with M-mode,
color, or power Doppler sonography.
D
possible to identify a normal intrauterine gestational sac
by TAS. Threshold levels of 500 to 1000 mIU/mL
(Second IS) have been proposed for TVS (1000-2000
for IRP).
Nonspecific Findings
When the sonographic findings are nonspecific, correlation with serum β-hCG levels improves the ability
of sonography to distinguish between intrauterine
and ectopic pregnancy. A negative β-hCG essentially
excludes the presence of a live pregnancy. The serum
β-hCG test yields positive results at approximately 23
days of gestational age.
108
This is before a normal intrauterine gestational sac may be imaged with TVS. Different types of sonographic techniques and equipment have
is recommended for the equipment and expertise in each
individual institution. If the hCG level is above the
threshold level, it should be possible to identify a normal
intrauterine gestational sac. If an intrauterine gestational
sac is not identified, an ectopic pregnancy becomes the
diagnosis of exclusion. An early complete or incomplete
abortion, however, may give a similar clinical and sonographic appearance. As noted earlier, published threshold levels do not take into consideration multifetal
pregnancies or patients with an enlarged uterus from
fibroids.
different hCG discriminatory levels above which gestational sacs are large enough to be imaged routinely.
Nyberg et al.
109
identified a β-hCG threshold level of
1800 mIU/mL (Second IS), above which it was always
sonogram may still identify an ectopic pregnancy. The
utility of the threshold level is to raise the index of sus-
picion for an ectopic pregnancy when no intrauterine
B
RO
C
The embryonic crown-rump length is 19 mm.
109
Some further refinement of a threshold level
110
If the β-hCG level is below the threshold level, the
1104 PART IV ■ Obstetric Sonography
gestational sac is identified. TVS should be performed
even when the β-hCG levels are low because some
patients may have suggestive or diagnostic findings. In
indeterminate cases when the patient is clinically stable,
serial quantitative serum hCG levels may be helpful in
distinguishing ectopic pregnancy, early pregnancy
failure, and early IUP. The β-hCG level in a normal
pregnancy has a doubling time of approximately 2 days,
whereas patients with a dead or dying gestation have a
falling β-hCG level. Patients with ectopic pregnancy
usually have a slower increase in hCG levels, although
they occasionally show patterns similar to a normal pregnancy or spontaneous abortion.
The presence of nonspecific adnexal findings improves
the ability of sonography to predict an ectopic pregnancy. An adnexal mass can be found in conditions other
than ectopic pregnancy (hemorrhagic corpus luteum
cyst, endometriosis, and abscess) and is therefore not
diagnostic. However, the presence of an adnexal mass in
patients without sonographic evidence of an IUP and a
positive β-hCG test result strongly suggests an ectopic
pregnancy. A suspected ectopic mass should be assessed
during the transvaginal examination for local tenderness.
The probe is used to apply light pressure on the mass.
This pressure almost always elicits pain similar to the
sensation that brought the patient to hospital initially.
Pain can also be felt with other inflammatory or expanding masses, such as a hemorrhagic corpus luteum.
Because the fallopian tube is the most common location
for an ectopic pregnancy, scanning with the vaginal
probe should allow for visualization of the ectopic pregnancy moving separate from the ovary as probe pressure
is applied. This motion helps distinguish between a hemorrhagic corpus luteum cyst and an ectopic pregnancy.
Fleischer et al.
103
found an ectopic tubal ring in 49%
of patients with ectopic pregnancy and in 68% of unruptured tubal pregnancies, using TVS (Fig. 30-39). The
tubal ring can usually be differentiated from a corpus
A
C
FIGURE 30-39. Isthmic ectopic pregnancy. A 35-year-old woman (G3P1A1) presented with no pain but was at risk for an
ectopic pregnancy. A, Coronal transvaginal scan shows an empty uterus and a tubal ring (arrow) immediately adjacent to the uterus.
B, Magnified view of the ring shows a gestational sac with a yolk sac, confirming an ectopic pregnancy. C, Color flow Doppler ultrasound
shows increased vascularity around the sac with high-velocity flow. D, At laparoscopy, ectopic site can be seen bulging the isthmic portion
of the tube (arrow). It was successfully removed by salpingostomy.
D
B
Chapter 30 ■ The First Trimester 1105
luteum cyst because the cyst is eccentrically located with
a rim of ovarian tissue. A tubal ring is a concentric ring
created by the trophoblast of the ectopic pregnancy surrounding the chorionic sac. This ring is often within a
hematoma that may be confined to the fallopian tube or
that may extend outside it. Frates et al.
111
found that an
ectopic tubal ring was more echogenic than ovarian
parenchyma, whether or not the sac was empty or had a
yolk sac or embryo. The corpus luteum in a proven IUP
was as or less echogenic than ovarian parenchyma in
93% of cases. The wall of the corpus luteum is usually
less echogenic than the endometrium. Stein et al.
112
found that the tubal ring of an ectopic pregnancy was
more echogenic than the endometrium in 32% of cases,
a finding that can be helpful in distinguishing between
a tubal ring and a corpus luteum cyst.
The ectopic tubal ring may be obscured or replaced
by a mass that is often echogenic (Fig. 30-40) but may
be of mixed echogenicity (Fig. 30-41). Easily overlooked
or mistaken for fat or bowel, these masses will be found
only with a high index of suspicion and careful TVS of
the adnexa, looking for the tubal ring or mass that is
focally tender.
Transvaginal ultrasound is extremely sensitive in
detecting free pelvic fluid. The presence of echogenic
free fluid (hemoperitoneum; Fig. 30-40, B) or blood
clots in the posterior cul-de-sac in pregnant patients,
without sonographic evidence of an IUP, should strongly
suggest an ectopic pregnancy. The presence of small
amounts of nonechogenic free fluid is nonspecific and is
seen in normal patients.
In 132 consecutive patients with surgical confirma-
tion, Frates et al.
113
found that the presence or the
amount of intraperitoneal fluid was not a reliable indicator of rupture. Rupture was present in 21% of patients
with no fluid and increasingly, up to 63%, with large
amounts. Interestingly, 37% of patients with a large
amount of fluid had intact tubes and no evidence
of rupture. Intraperitoneal fluid is possible if the
blood escapes through the fimbriated end of the intact
fallopian tube.
Implantation Site
Ectopic pregnancy may occur in several sites. Approximately 95% of ectopic pregnancies occur in the ampul-
ff
A
ro
C
FIGURE 30-40. Ectopic pregnancy seen as echogenic mass. A 33-year-old woman presented at 7 weeks’ gestation with
right lower quadrant pain. A, Transvaginal scan shows an empty uterus. B, Free fluid (ff) in the cul-de-sac. C, In right adnexa there was
a 1.4 × 1.6–cm echogenic mass (arrow) adjacent to a normal ovary (ro). The mass was focally tender to palpation with the vaginal probe.
D, Power Doppler ultrasound shows minimal internal vascularity.
B
D
1106 PART IV ■ Obstetric Sonography
A
B
FIGURE 30-41. Ectopic pregnancy seen as mixed-
echogenicity mass. A 30-year-old woman presented with
left lower quadrant pain at 7 weeks’ gestation and β-hCG of
500 mIU/mL and falling over a 3-day period. A, In the left
adnexa, medial to the left ovary, there was a 2-cm mass (arrow)
with mixed echogenicity, and B, only minimal peripheral vascularity. A left ectopic pregnancy was confirmed and based on a
falling β-hCG was treated expectantly and resolved without
complication.
lary or isthmic portions of the fallopian tube. The second
most common site, about 2% to 3% of all ectopic pregnancies, is an interstitial pregnancy occurring in the
intramural portion of the tube, where it traverses the wall
of the uterus to enter the endometrial canal. Ovarian,
cervical, and abdominal sites of ectopic pregnancy are
extremely rare.
Implantation in the superior lateral portion of the
endometrial canal but not within the intramural portion
of the tube is normal and is not an ectopic pregnancy.
This is often mistaken for an ectopic pregnancy, but
echogenic endometrium can be seen around the sac
(double-decidual sign), and if followed even for 1 week,
the sac grows and usually extends into the endometrial
canal.
Because of its intramural location, interstitial ectopic
pregnancies (cornual) rupture later than other tubal
gestations, often causing massive intraperitoneal hemorrhage from the dilated arcuate arteries and veins, which
lie in the outer third of the myometrium between the
thin outer myometrium and the thick intermediate layer.
The mortality of interstitial pregnancy is twice that of
other ectopic pregnancies. Ackerman et al.
114
found that
the two currently used sonographic signs of myometrial
thinning and sac eccentricity are unreliable and described
the more useful interstitial line sign (Fig. 30-42).
The interstitial line is a thin, echogenic line extending
from the endometrial canal up to the center of the interstitial sac or hemorrhagic mass. It was seen in 92% of
interstitial ectopic pregnancies. The line is the nondistended, empty endometrial canal. The interstitial ectopic
pregnancy is usually surrounded by trophoblast but
should not have a double-decidual sign. Thinning of the
myometrial mantle was seen in three of four interstitial
sacs; however, eight additional patients had only a
mass, with no sac, and therefore no mantle thinning or
eccentricity of the sac. All these sacs had an interstitial
line. Treatment is usually laparotomy and cornual
resection, although methotrexate therapy may be preferable, depending on the size of the interstitial ectopic
pregnancy.
Cervical scar implantation appears to be increasing,
with more cases appearing in the literature.
115
The
patient may present with painless vaginal bleeding and
a history of one or more cesarean sections. An early
sonogram will show a sac implanted in the lower uterine
segment, with local thinning of the myometrium (Fig.
30-43; Video 30-5). There is usually prominent vascu-
larity at the implantation site. Catastrophic hemorrhage
may result, with the need for complete hysterectomy
and, if involved, major bladder reconstruction. Remember that an aborting gestational sac may present in the
lower uterine segment on its way out of the uterus.
Sonographically, the sac will be oblong, the embryo if
present will be dead, and there will be no trophoblastic
vascularity because it has detached from the uterine
wall. Vascularity is an important distinguishing feature
between a cervical scar implantation and an incomplete
abortion. Clinically, both situations are associated with
vaginal bleeding, but the abortion more likely with
crampy pain as well. Treatment of a scar implantation is
often protracted. A D&C is seldom advised because the
thin lower segment may be perforated. Medical therapy
is more common, with methotrexate taken systemically
and often injected locally as well. Presence of a live
embryo may require careful injection of potassium chloride (KCl) into the embryo to stop cardiac activity.
Cervical pregnancy is rare. As in scar pregnancy,
vascularity is an important distinguishing feature between
a cervical implantation and an incomplete abortion.
Treatment is typically with injection of KCl. Abdominal
pregnancies are also rare. When diagnosed in the first
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