Objective The aim of this study was to review the outcome of fetal exomphalos detected at 11–14 weeks of gestation.

Method Retrospective study of cases of exomphalos identified from the Fetal Medicine Unit database, University College London Hospitals between January 1998 and January 2010. Pregnancy and neonatal data were ascertained from maternal and neonatal records. Fetal exomphalos was categorized into three groups: exomphalos associated with other major structural malformation(s) (A), isolated exomphalos with increased nuchal translucency (NT) (B) and with normal NT (C).

Results 98 cases of exomphalos were identified, of which 45 cases (45.9%) were associated with other major structural malformation(s) (Group A). Isolated exomphalos with increased NT (Group B) was found in 22 cases (22.4%), and with normal NT (Group C) in 31 cases (31.6%). Of 74 (75.5%) fetuses that were karyotyped, 43 (58.1%) had a chromosomal abnormality; the most common aneuploidy was trisomy 18 (n=31, 72.1%). In Groups A and B, the incidence of aneuploidy in those with a known karyotype was 78.9% and 72.2% respectively. Cases of isolated exomphalos with normal NT (Group C) were all euploid. In 21 (21.4%) babies, exomphalos resolved later in pregnancy and none had any apparent abnormalities at birth; only three neonates (3.1%) had an isolated exomphalos.

Conclusions A high proportion of fetuses with exomphalos and either another abnormality or isolated with increased NT in the first trimester had an abnormal karyotype. All fetuses with isolated exomphalos with normal NT were euploid.