Sirenomelia With Anhydramnios: A Clue From the Movements of Fetal Limbs

Abstract

Sirenomelia is a rare, lethal congenital malformation of the fetus, typically characterized by the fusion of lower limbs and additional malformations involving the lumbosacral spine and urogenital and gastrointestinal tracts. We report a case of sirenomelia with anhydramnios detected during anomaly scan where the fetus had normal morphology of long bones of the lower limbs. There were associated abnormalities of the lumbosacral spine (caudal dysgenesis). The abortus had fused lower limbs, absent external genitalia and anal orifice, single umbilical artery, and Potter facies. We also highlight the interesting diagnostic challenges faced by us during this antenatal ultrasound. To our knowledge, this is the first case report of sirenomelia where the synchronous movement of lower limbs was a clue that led to the timely antenatal detection of this rare entity. This ultimately helped in perinatal counseling of parents to decide on termination of pregnancy.