ultrasound diagnosis of fatal anomalies

CHROMOSOMAL DISORDERS
before 18 weeks). In 25%, hydramnios is detected.
A singular umbilical artery is a common
finding. Fifteen percent show hygroma colli. Microcephaly,
with a typical ”strawberry-shaped
head,“ is characteristic. Other anomalies are:
neural tube defects (20%), cysts of the choroid
plexus (25%), widening of the cisterna magna
(more than 10 mm) and agenesis of the corpus
callosum. Other frequently associated malformations
are: microgenia, overlapping fingers—
“clenched fist“ (the fourth finger lies over the
third and the fist cannot be opened), diaphragmatic
hernia (10%), omphalocele (25%; typically
the hernia contents are solely intestines) and
renal anomalies. Eight percent of cases have cardiac
anomalies, especially VSD, tetralogy of Fallot,
and aortic isthmus stenosis. Shortening of
the extremities is common, and other limb
anomalies may be seen in 50%. Rocker-bottom
foot is a typical feature (convexity of foot soles
and prominent heel). Club feet, malformation or
absence of the thumb and radius aplasia can also
be detected. Ninety percent of trisomy 18 cases
can be diagnosed at the prenatal stage by an abnormal
measurement of nuchal translucency
and screening for organ anomalies.
Differential diagnosis: Freeman–Sheldon syndrome,
Pena–Shokeir syndrome, Smith–Lemli–
Opitz syndrome, triploidy, trisomy 9 mosaic,
and other syndromes showing growth restriction.
Fig. 9.28 Trisomy 18. Early fetal hydrops,
12+3weeks.
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Fig. 9.29 Trisomy 18. Fetal head at 19+1weeks,
showing the strawberry sign.
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