Sirenomelia: mermaid syndrome.

Sirenomelia, or "mermaid syndrome," represents a severe form of caudal regression. It is a rare congenital malformation that is incompatible with life. In the following case report, a double inferior vena cava was also present, and this anomaly in association with sirenomelia has not been reported. Ultrasound may be useful in the early antenatal detection of this anomaly. This is the first case of sirenomelia reported in the black race.