ultrasound diagnosis of fatal anomalies

SOFT MARKERS OF CHROMOSOMAL ABERRATIONS
Caution: Following some initial euphoria regarding
the use of this ratio to detect Down syndrome,
large studies have since shown that there
is a normal biological variation in head size and
that potential measurement inaccuracies may
lead to incorrect conclusions. The ratio has
therefore lost its importance as a soft marker for
detecting chromosomal disorders. When
brachycephaly is found, the examiner should be
alerted to other possible malformations. The
head ratio should not be commented on in relation
to chromosomal disorders, as this may
cause unnecessary anxiety for the parents.
References
Becker R, Brinnef C, Arabin B. Der Kopfindex—ein vernachlässigter
Parameter der fetalen Standardbiometrie.
Ultraschall Med 1992; 13: 2–6.
Borrell A, Costa D, Martinez JM, et al. Brachycephaly is
ineffective for detection of Down syndrome in early
midtrimester fetuses. Early Hum Dev 1997; 4: 57–61.
Buttery B. Occipitofrontal-biparietal diameter ratio: an
ultrasonic parameter for the antenatal evaluation of
Down’s syndrome. Med J Aust 1979; 2: 662–4.
Stempfle N, Huten Y, Fredouille C, Brisse H, Nessmann C.
Skeletal abnormalities in fetuses with Down’s syndrome:
a radiographic post-mortem study. Pediatr
Radiol 1999; 29: 682–8.
Dandy–Walker Variant (Open Cerebellar Vermis)
Definition: A connection between the fourth
ventricle and the cisterna magna is a normal
finding up to 18 weeks of gestation; thereafter,
this diagnosis is applicable. It is advisable to determine
the chromosome set, as an association
with a chromosomal disorder is frequent.
Detailed ultrasound screening should also be
carried out to detect other malformations. The
boundary to Dandy–Walker syndrome is hazy.
Caution: At 13 weeks of gestation, Dandy–
Walker variant is almost always detectable, and
is considered to be a normal finding up to
18 weeks.
Prognosis: This may be a harmless finding with a
good prognosis, or may be associated with other
syndromes with a poor prognosis.
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3
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5
Associated syndromes: Smith–Lemli–Opitz syndrome,
Joubert syndrome, Meckel–Gruber syndrome,
Neu–Laxova syndrome, Walker–Warburg
syndrome, Ellis–van Creveld syndrome,
Majewski syndrome, TAR syndrome, tetrasomy
12 p, triploidy, trisomy 9, trisomy 18, arthrogryposis,
CHARGE association, Fryns syndrome,
MURCS association.
Ultrasound findings: A small, slit-like connection
is detected between the fourth ventricle and the
cisterna magna, without widening of the latter.
This finding distinguishes the Dandy–Walker
variant from the Dandy–Walker syndrome.
False-positive as well as false-negative findings
can be produced by inaccurate ultrasound scanning
in the wrong plane.
References
Blaicher W, Ulm B, Ulm MR, Hengstschlager M,
Deutinger J, Bernaschek G. Dandy–Walker malformation
as sonographic marker for fetal triploidy. Ultraschall
Med 2002; 23: 129–33.
Bromley B, Nadel AS, Pauker S, Estroff JA, Benacerraf BR.
Closure of the cerebellar vermis: evaluation with
second trimester US. Radiology 1994; 193: 761–3.
Ecker JL, Shipp TD, Bromley B, Benacerraf B. The sonographic
diagnosis of Dandy–Walker and Dandy–
Walker variant: associated findings and outcomes.
Prenat Diagn 2000; 20: 328–32.
Laing FC, Frates MC, Brown DL, Benson CB, Di Salvo DN,
Doubilet PM. Sonography of the fetal posterior fossa:
false appearance of mega-cisterna magna and
Dandy–Walker variant. Radiology 1994; 192: 247–
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