Women"s and Children"s Hospital, South Australia
Routine 19 week scan, no relevant family history. The long bone lengths were normal. The hands were never seen to open. 3D of the head was not of diagnostic quality. A normal -sized stomach was not identified on two scans.
Diagnosis: Apert"s syndrome (acrocephalosyndactyly). In our (limited) experience, it is unusual for craniostenoses (other than type II thanatophoric dysplasia) to be convincingly outside the range of normal variation in the 2nd trimester, so it was assumed that this would be at the severe end of the spectrum. The parents opted to terminate the pregnancy.
The fetus also had oesophageal atresia, which is not a known association of Apert"s.
Most cases of Apert"s arise from new mutations, but a few come from parental gonadal mosaicism, so there is a small risk of recurrence. Two common mutations are known to be responsible for 97% of autosomal dominant Apert syndrome. They are within exon 7 of the fibroblast growth factor 2 receptor gene (FGFR2), and can be detected in amniotic fluid cells. (Ref: Chun et al. Am J Med Genet. 120A: 470-473, 2003).
Craniostenoses restrict the skull"s ability to mould in labour. If a head shape raises concern in the third trimester, it is prudent to arrange a "scout film" CT or X-ray of the maternal abdomen, with a view to elective caesarian section if a craniostenosis is confirmed. Sagittal synostosis in particular gives a high risk of a poor neurological outcome if the fetus is allowed to undergo labour and vaginal delivery.
Transversal scans of the skull