Diagnostic ultrasound ( PDFDrive )

1206 PART IV Obstetric and Fetal Sonography
CC
CC
cb
A
B
FIG. 34.33 Vein of Galen Aneurysm. (A) Midsagittal view shows a hypoechoic “cyst” (arrow) behind the brainstem and under the splenium
of the corpus callosum (cc). cb, Cerebellum. At irst glance it could be mistaken to be a large cavum veli interpositi. (B) Color Doppler examination
shows the prominent vascularity characteristic of this malformation.
sd
FIG. 34.34 Sagittal Sinus Thrombosis. There is an echogenic mass
(arrow) in a luidlike space in the midline anteriorly. This represents
thrombus in a dilated sagittal sinus. There is also a subdural collection
(sd). (Courtesy of Dr. K. Fong, Mt. Sinai Hospital, Toronto, Ontario).
the second and third trimesters and can be conirmed with MRI,
which also helps to evaluate the brain for other abnormalities
and areas of hemorrhage. Diferential diagnosis includes tumors,
intracranial bleeding, and dural sinus malformations. A substantial
proportion resolve spontaneously over 3 to 11 weeks. he
prognosis appears good if no other abnormalities are found and
the brain appears normal. 11,245
Hemorrhagic Lesions
Intracranial hemorrhage describes bleeding in and around the
brain. he incidence is about 1 per 10,000 live births. 246 he
most common sites are similar to those seen in premature
neonates. In a series of 109 antenatal intracranial bleeds, 89 were
intracerebral (79 intraventricular, 10 infratentorial), and 20 were
subdural. 247 As in neonates, cerebral bleeds are graded from 1
to 4 and may be followed by chemical ventriculitis (thick
echogenic ventricular lining), hydrocephalus, porencephalic
cysts, white matter injury, and periventricular leukomalacia.
About half are idiopathic. Predisposing factors include hypoxia,
fetal coagulation disorders (including alloimmune thrombocytopenia
and maternal anticoagulation), death of a monochromic
co-twin, seizures, viral or bacterial infection, febrile
disease, drugs (cocaine), maternal-fetal hemorrhage, and
trauma. 11,246-248
On ultrasound, the bleed appears as an echogenic collection
in the ventricles and surrounding brain (Fig. 34.35). his hemorrhage
later organizes and condenses into clots and may be
associated with VM and echogenic thickening of ventricular
walls (chemical ventriculitis). he indings may resolve or progress
to HC, porencephaly, cerebral clets, and cortical malformations.
hose with ischemia may also develop cystic leukomalacia.
Subdural hemorrhages appear as an echogenic collection underlying
the skull and compressing the adjacent brain. 246,247
he prognosis varies greatly and depends largely on fetal age,
extent of injury, and underlying factors. About 50% die in utero
or shortly ater birth, and about half the survivors have deicits.
As expected, some with mild changes may resolve completely,
and more severe (grade 3-4) changes and cerebral changes predict
a poor outcome. Ultrasound can accurately diagnose bleeds, but
MRI can more accurately deine the extent of the lesion and may
demonstrate additional ischemic changes in white matter 246,247
(see Fig. 34.35). Investigation of suspected cases includes trauma
and drug history, as well as maternal screening for antiplatelet
antibodies and thrombophilia. 246,248