Diagnostic ultrasound ( PDFDrive )

CHAPTER 30 The First Trimester 1073
A
B
C
FIG. 30.31 Tubal Findings in Ectopic
Pregnancy. (A) TVS of the left adnexa shows
an extraovarian tubal mass (calipers). (B) Color
Doppler demonstrates concentric low around
the mass. Hypoechoic material surrounds the
tubal ring consistent with hematoma. (C) In
another patient, sagittal TVS shows the ectopic
mass (thin arrows) inferior to the ovary (dashed
arrow). See also Video 30.7.
echoes due to blood, but they can be smooth and rounded with
debris that could be mistaken for products of conception. 104,109
Implantation Sites
Ectopic pregnancy may occur in several sites. Approximately
95% of ectopic pregnancies occur in the ampullary or isthmic
portions of the fallopian tube. he second most common site,
about 2% to 4% 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 103
(Fig. 30.32).
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. his is oten 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 attains a more typical appearance in
the endometrial canal. hree-dimensional ultrasound can add
in the conidence of the diagnosis of both interstitial ectopic and
eccentric intrauterine pregnancy. 119
Because of the distensibility of this portion of the fallopian
tube, interstitial ectopic pregnancies may present and rupture
later than other tubal gestations, oten 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. 119
he mortality of interstitial pregnancy is twice that of other
ectopic pregnancies. Ackerman et al. 120 found that the two currently
used sonographic signs of myometrial thinning and sac
eccentricity are unreliable and described the more useful interstitial
line sign. he 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. he line is the nondistended,
empty endometrial canal. he interstitial ectopic pregnancy is
usually surrounded by trophoblast but should not have a doubledecidual
sign. Treatment historically was surgical with cornual
resection, but now less invasive therapy with local injection of
potassium chloride or with local or intramuscular injection of
methotrexate is performed to avoid uterine surgery. Occasionally
this type of ectopic pregnancy is mistakenly called a “cornual
pregnancy.” However this term should be reserved for a gestational
sac lying within a rudimentary horn or within one horn
of a bicornuate uterus. 119
Cervical ectopic pregnancies are to the result of implantation
in the endocervical canal (Fig. 30.33). hey are rare, accounting