Discordant malformation in a monozygotic pregnancy: abdominoschisis and sirenomelia

Abstract

Abstract Congenital malformations occur in up to 10% of monochorionic twins and are usually discordant. Body wall defect (BWD) is a rare entity of very low prevalence, defined as a combination of various malformations, including fetal body mutilations of thoracic and/or abdominal organs that can be caused by amniotic rupture early in embryonic development. Sirenomelia is a form of caudal regression syndrome that presents with lower limb fusion, among other anomalies. In this report, we will present a second trimester monochorionic diamniotic pregnancy, with BWD-abdominoschisis in one fetus and sirenomelia in the other one. Amniotic bands could not be found. Of particular importance in respect to both malformations is the timing of the insult that could have caused both anomalies.