A Case of Postnatally Diagnosed Sirenomelia in a Patient with Poorly Controlled Type 2 Diabetes Mellitus

Abstract

Sirenomelia, also known as mermaid syndrome, is a rare constellation of anomalies of caudal fetal development associated with fusion or complete absence of the lower limbs. The prognosis for neonatal survival is poor. Diagnosing this condition can pose a challenge due to associated oligo/anhydramnios. First-trimester transvaginal and transabdominal anatomy ultrasound performed between 11-13.6 weeks of gestational age (WGA) can evaluate fetal anatomy for anomalies. Transvaginal (TVUS) ultrasound offers the best opportunity to detect this condition. We present a case of a 1240g baby born from a 34yo with poorly controlled type 2 diabetes (T2DM) delivered via repeat cesarean section. Antenatal management for presumed previable pre-labor rupture of membranes (PROM) was provided. Postnatally, the infant had unexpected defects consistent with Sirenomelia. The neonatal exam showed webbed legs due to fused knees and toes, microcephaly, two-vessel umbilical cord, ambiguous genitalia, and bilateral renal agenesis. After confirming bilateral renal agenesis, we provided palliative care. The neonate died 12 hours after birth from cardiac arrest.