Diagnostic ultrasound ( PDFDrive )

CHAPTER 43 Sonographic Evaluation of the Placenta 1479
H
I
FIG. 43.19, cont’d (H) and (I) Placental chorioangioma (arrow) in another patient (I taken 4 weeks after H). The chorioangioma is relatively
homogeneous and similar in echogenicity to the placenta.
MESENCHYMAL DYSPLASIA
OF THE PLACENTA
Mesenchymal dysplasia of the placenta resembles a partial
hydatidiform mole both grossly and microscopically, with a
thickened placenta and small cystic lesions. he appearance of
the placenta has been described as having a “stained-glass”
appearance when color Doppler sonography is used, due to the
low noted in the multiple placental cysts. 125 In contrast to partial
moles, mesenchymal dysplasia of the placenta may be associated
with a normal fetus, although IUGR is common. here is also
an association with Beckwith-Wiedemann syndrome 126 (Fig.
43.20). he villi in these cases are cystic with dilated vasculature.
he karyotype is usually normal. 127
MOLAR GESTATIONS
Gestational trophoblastic disease consists of complete mole
(Fig. 43.21) and partial mole and choriocarcinoma. hese
placental abnormalities are discussed in detail in Chapter 30.
FIG. 43.20 Mesenchymal Dysplasia of Placenta. Associated with
Beckwith-Weidemann syndrome at 20 weeks’ gestation. Note the
enlarged placenta (8 cm, calipers) with multiple cystic spaces.
MORPHOLOGIC PLACENTAL
ABNORMALITIES
here are a number of placental shape abnormalities, some quite
common, and some quite rare. New evidence suggests that the
development of placental shape abnormalities originates from
placental vascular abnormalities in the irst trimester, also leading
to umbilical cord insertion abnormalities. 11
Circumvallate Placenta
In circumvallate placenta the membranes of the chorion laeve,
instead of inserting at the margin of the placental disc, insert
more toward the center of the disc. he pathologist can identify
ibrin at the margin along with evidence of bleeding. With a
complete circumvallate placenta, a ring may constrict the chorion
frondosum. 28 Because of this placement, there is disproportionate
folding of the placenta and fetal membranes. his results in the
chorionic plate being smaller than the basal plate. Within the
membrane fold, hyalinized villi may be seen ater being incorporated
into the fold.
Circumvallate placenta has the sonographic appearance of a
rolled edge of membranes at the placental edge inserting toward
the center of the placental chorionic disc (Fig. 43.22, Videos
43.12 and 43.13). Termed a placental shelf, this rolled edge of
membranes can be thick and most oten occupies only a small