Mermaid baby or sirenomelia: a lethal congenital anomaly

Mermaid syndrome is a very rare, lethal congenital anomaly. It is associated with other congenital anomalies and is incompatible with life. Typical clinical features are fused lower limb from perineum to ankle and single umbilical artery. Etiology is multifactorial and is extreme form of caudal regression syndrome. When diagnosed in early gestation, termination of pregnancy may be considered.