Diagnostic ultrasound ( PDFDrive )

CHAPTER 30 The First Trimester 1083
A
B
FIG. 30.44 Choriocarcinoma After Normal Pregnancy. (A) Sagittal and (B) transverse TVS images show an ill-deined endometrium (arrows)
with multiple large cystic spaces. See also Video 30.11.
complex and multicystic, similar to molar tissue. hick-walled,
irregular anechoic areas may be seen, resulting from tissue necrosis
and hemorrhage. 153-155 In other cases, anechoic areas within lesions
represent vascular spaces. When tumor replaces the entire
myometrium, the uterus is enlarged, with the myometrium
appearing heterogeneous and lobulated. he tumor may extend
beyond the uterus to the parametrium, pelvic side wall, and
adjacent organs. In extreme cases, PTN appears as a large, undifferentiated
pelvic mass. Sonography can be diagnostic in the
correct setting (e.g., recent molar pregnancy, rising serum hCG,
previously documented normal sonogram).
Ater efective therapy, sonographic lesions become progressively
more hypoechoic and smaller in size. Eventually, no residual
abnormality is apparent in many cases. However, up to 50% of
patients will have persistent abnormalities ater therapy that may
be diicult to distinguish from active lesions sonographically.
Duplex and color Doppler ultrasound features of PTN relect
the marked hypervascularity of invasive trophoblast. 156,157 Uterine
spiral arteries feed directly into prominent vascular spaces, which
then communicate with draining veins. hese functional
arteriovenous shunts produce abnormal uterine hypervascularity
and high-velocity, low-impedance blood low on duplex interrogation.
156 Trophoblastic blood low has characteristic, high
PSV and low RI. PSV is usually greater than 50 cm/sec and is
oten over 100 cm/sec. RI is usually less than 0.5 and is oten
well below 0.4. In contrast, normal myometrial blood low usually
has a PSV of less than 50 cm/sec and an RI in the range of 0.7.
Color Doppler sonographic features typical of PTN include
extensive color aliasing, admixture of color signals, loss of discreteness
of vessels, and chaotic vascular arrangement. Regions of
abnormal color Doppler ultrasound frequently appear larger than
corresponding sonographic abnormalities.
Trophoblastic signals on spectral Doppler ultrasound are not
unique to PTN. hey are seen in all conditions with functioning
trophoblast, including failed pregnancy, retained products of
conception, and ectopic pregnancy. hese potential pitfalls are
distinguished from PTN by clinical indings, sonographic
morphology, and pathology. However, PSTT should remain a
consideration even with a normal hCG level. In most patients
the diagnosis of PTN is fairly straightforward, and additional
information provided by Doppler ultrasound is supportive but
not critical. However, when PTN is not suspected clinically, duplex
and color Doppler sonography may provide the irst indication
of trophoblastic disease by showing marked hypervascularity
and typical trophoblastic blood low within lesions. Doppler
ultrasound also improves diagnostic speciicity by showing normal
uterine waveforms when PTN is absent and sonography is
abnormal, as when other uterine lesions mimic the appearance
of PTN, or persistent nonspeciic abnormalities remain ater
efective therapy. 157
Diagnosis and Treatment
Because PTN arises most oten ater a molar pregnancy, the
diagnosis is usually based on abnormal regression of hCG ater
uterine evacuation. A histologic diagnosis is not considered
mandatory because curettage risks uterine perforation and does
not signiicantly alter management or outcome. 151,158 Patients are
treated on the basis of clinical staging that includes computed
tomography of the brain, chest, abdomen, and pelvis.
With the exception of PSTT, hCG level is a sensitive and
speciic marker for detecting and monitoring PTN. Normal mean
disappearance time of hCG in benign moles ranges from 7 to
14 weeks (median, 11 weeks) but can be as long as a year.
Contraception is recommended for 6 months ater a normal
hCG has been attained in order to distinguish a rising hCG
resulting from persistent or recurrent disease from that due to
pregnancy. 133
PTN is broadly classiied as nonmetastatic or metastatic on
the basis of staging computed tomography of the brain, chest,
abdomen, and pelvis. 151,158 Nonmetastatic PTN has an excellent
prognosis. Single-agent therapy with methotrexate achieves
sustained remission in virtually 100% of cases. 158 Metastatic PTN
is subdivided into low-risk and high-risk groups. Virtually all
patients with low-risk metastatic disease are cured with simple
chemotherapy. 151 In contrast, patients with high-risk disease have
a substantially worse prognosis and a high likelihood of failure