Sirenomelia - A Case Report
Sirenomelia is a severe and complex malformation with an incidence of 0.8 to 1 cases per 1,00,000 births and a male/female ratio of 3:1. Uptil now, about 300 cases, have been reported in the literature. The malformation sequence consists of different degrees of lower limbs fusion so that the affected infant bears resemblance to the mermaid of ancient greek mythology. Characteristically, severe malformations of gastrointestinal, musculoskeletal, vascular, cardiopulmonary, and central nervous system malformations are associated to the union of the lower extremities. Oligohydraminos secondary to renal agenesis or renal dysgenesis, is a nearly universal finding, and is associated with an extremely poor prognosis. Only a handful of patients with sirenomelia have been reported to have survived beyond the neonatal period.
We herein report a 23 year old primigravida mother who delivered a post term (43 weeks) baby by normal vaginal delivery weighing 1645 grams, cried immediately after birth (with an APGAR score of 8 and 9 at 1 and 5 minutes respectively ), with intrauterine growth retardation. The baby was admitted to the anomalies. Physical examination of the newborn revealed normal vital signs. Dysmorphic features noted were low-set ears with deformed ear cartilage and single umbilical artery. A sireniform malformation was seen with complete soft tissue fusion of lower limbs from perineum to ankles. The fused extremities were almost 90 degrees flexed over the hips and had limited motility. The anus was absent , as were external genitalia. The infantogram revealed pulmonary hypoplasia and absence of pelvic bones, fusion of both femur resulting in single thigh bone and rudimentary tibia and fibula. The post- natal ultrasonography of the abdomen confirmed the dysgenesis of the urogenital system. The pregnancy was unremarkable, with no history of maternal diabetes or exposure to teratogens. The antenatal ultrasonography (USG) done was unremarkable except for severe oligohydraminos.
Sirenomelia is fatal in most cases because of the characteristic pulmonary hypoplasia and renal agenesia. In our case the renal agenesis and pulmonary hypoplasia contributed to mortality. The baby survived for 8 hours.