Syrenomelia

Sirenomelia (sirenomelia; Greek seiren siren + melos body part, limb; synonym: sympus, siren) is a rare congenital developmental anomaly in which the lower limbs are fused, forming a single underdeveloped limb, reminiscent of a mermaid’s tail.

The cause of sirenomelia is disturbances in the blood supply to the embryo in the early stages of pregnancy. The result is an abnormal fusion of the lower extremities. The degree of fusion of the legs can be different - from partial fusion of the feet to the complete absence of separation of the legs along the entire length.

Sirenomelia is often combined with other developmental defects - anomalies of the urinary system, genital organs, and spine. The survival rate of children with severe forms of sirenomelia is extremely low. Treatment consists of surgical separation of the fused limbs and correction of associated anomalies.