Diagnostic ultrasound ( PDFDrive )

CHAPTER 43 Sonographic Evaluation of the Placenta 1481
A
B
FIG. 43.23 Mimics of Circumvallate Placenta. (A) Placenta abutting a uterine synechia (long arrow) of myometrial tissue; short arrow, placental
edge. (B) Transabdominal sonogram of a second-trimester pregnancy with a uterine septum (arrow). The placenta partially inserts on the uterine
septum.
A
B
FIG. 43.24 Succenturiate Lobe. (A) Transabdominal sonogram shows two placental components (arrows). (B) Color Doppler demonstrates
the vascular connection between the succenturiate lobe and the main placental disc.
minimum, the internal cervical os should be evaluated to assess
for the presence of fetal vessels.
Bilobed Placenta
Bilobed placentas consist of two similarly sized placental lobes
separated by intervening membranes (Fig. 43.25, Video 43.14).
here must be some vascular connection between the lobes, and
the umbilical cord may insert in the membranes between the
lobes. Although rare, a bilobed placenta can be regarded similar
to succenturiate lobes, with similar risks. Bilobed placentas may
have more unprotected vessels, however, reinforcing the need
for careful evaluation of the placental vasculature in
such cases.
UMBILICAL CORD
Size and Appearance
Umbilical cord length varies, and a normal length has not been
established. However, extremes of cord length are associated
with abnormal outcome. Short umbilical cords are associated
with conditions that impair fetal movement early in gestation,
such as akinesia syndromes, aneuploidy, and extreme IUGR.
Excessive cord length is associated with asphyxia or death
resulting from a variety of situations that compromise cord low,
including excessive coiling, true knots, multiple loops of nuchal
cord, and cord prolapse.