Case History: A 28 years old pregnant woman with evidence of polyhydramnios on ultrasound, delivered a baby (34 weeks) with birth weight 1.8 kg with low set large dysplastic ears with flattened nose, fused lower extremities in external and dorsal rotation, Patellae dorsal, popliteal fossae ventral dorsolaterally large dysplastic fibulae with sharp lateral tapering of the bone. Absence of external genitalia in the expected location with imperforate anus was found along with single umbilical artery.

Kidigram reveals Patellae are dorsal and the popliteal fossae ventral. Resuscitation done with Ambu bag ventilation, but baby did not survive.

Sirenomelia is a characteristic malformation syndrome with fused lower extremities, external and dorsal rotation of these symmelian extremities, dorsally located patellae and ventrally located popliteal fossae absent external genitalia, anal atresia, rental anomalies and hypoplasia of lungs. It is a primary defect of caudal axis skeleton during the third embryonal week. It is hundred times more frequent with uniorular twins than with single births. Ratio of males to females is 2.7:1
Frequency: About 300 cases reported in world literature.
Prognosis: Stillbirth and death within a few hours. Treatment: No therapeutic efforts known to date can ensure survival prenatal diagnosis with ultrasound in women with oligohydramnios and intrauterine growth retardation.