Diagnostic ultrasound ( PDFDrive )

556 PART II Abdominal and Pelvic Sonography
A
B
C
FIG. 15.28 Acquired Arteriovenous Malformation (AVM). AVM in a patient 9
weeks postpartum, 2 weeks after dilation and curettage, with continued vaginal bleeding.
(A) Sagittal TVS shows a focal area of serpiginous cystic-appearing structures (arrow)
in the fundal myometrium. (B) Sagittal TVS shows low in the serpiginous structures.
(C) Sagittal TAS shows high-velocity, low-resistance arterial low. (Courtesy of Marilyn
Morton, DO.)
Endometritis is a clinical diagnosis. he sonographic indings
are variable and may be normal. 190 Fluid and/or air may be seen
in the endometrial cavity in patients with endometritis, but these
are also common normal indings in the irst few postpartum
weeks, limiting their usefulness.
Arteriovenous Malformation
Arteriovenous malformations (AVMs) are rare. In general, they
are acquired lesions resulting from prior uterine instrumentation.
Although they can be seen at other times, they are oten diagnosed
during the postpartum period or ater a miscarriage, and patients
usually have abnormal vaginal bleeding on presentation. It is
important to diagnose AVM so that inappropriate treatment
does not worsen the hemorrhage. 13
Sonographically, AVMs should be considered when there is
focal area of serpiginous tubular structures in the myometrium.
195,196 Color or power Doppler imaging will typically show
exuberant low in the AVM (Fig. 15.28), and spectral Doppler
imaging will demonstrate low-resistance arterial low. It has been
suggested that the arterial velocities in the AVM may guide
treatment, with higher velocities (>83 cm/sec) suggesting the
need for embolization and lower velocities allowing for more
conservative management. 197 However, in most published studies
the reported velocities are not true velocities because angle
correction was not used, confounding the usefulness of such
measurements.
Uterine AVMs can be easily overdiagnosed in the postpartum
and postmiscarriage periods. 198 Findings similar to true AVMs
can be due to subinvolution of the placental bed. 199 hus in
stable patients one should try for conservative management
because many of these seeming AVMs will resolve spontaneously.
Focal areas of low-resistance arterial low may also be seen in
the myometrium in patients with RPOC and gestational trophoblastic
disease, similar to an AVM. 200 A negative serum hCG
may be helpful because hCG is typically elevated in patients with
gestational trophoblastic disease. 13 Serum hCG level may not be
as helpful for RPOC; about half of patients with RPOC are
reported to have a negative or only minimally positive hCG
level. 201
Findings After Cesarean Section
Most patients undergoing a cesarean delivery will have a transverse
incision in the lower uterine segment. In the initial postpartum
period ater a cesarean section, one typically will see small
echogenic foci, due to sutures and/or gas, in the anterior myometrium
of the lower uterine segment (Fig. 15.29A, Video 15.13).
It is uncertain how long these can normally be seen but likely
for several weeks or months. One may also see heterogeneity in
this region of the myometrium, probably due to small areas of
hemorrhage. For the minority of cesarean section patients who
have a classic hysterotomy with a longitudinal incision higher
in the uterus, one may see similar heterogeneity and/or echogenic
foci in that region of the myometrium in the postpartum period.
Bladder lap hematomas, due to bleeding at the incision site,
may occur in the lower uterine segment of the uterus or between
it and the urinary bladder. Sonographically, they appear as a
mass of variable echogenicity (see Fig. 15.29B, Video 15.13).
Small hematomas are common and may not be clinically