A case report of body stalk anomaly complicating a twin pregnancy.

The body stalk anomaly is described as a maldevelopment during embryonic folding in the third week after conception, resulting in a severe defect of the fetal abdominal wall. The extra-embryonic coelom fails to obliterate and parts of the fetal body remain in an exo-coelomic situation. Reports on its occurrence in multiple pregnancies have in the past focused on concordance between monozygotic twins. We report on a case of a twin pregnancy after fertility treatment that was complicated by a Body Stalk Anomaly in one of the fetuses with a positive neonatal outcome of the unaffected twin.