Clinical Imaging, Anatomical and Embryological Classification of Sirenomelia, A Case Report

Sirenomelia or mermaid syndrome is a Very Rare congenital Defect (VRD) with a reported prevalence of 0.98 per 100,000 births, where the normally paired lower limbs are replaced by a single midline limb. With few exceptions, sirenomelia is a lethal condition in the perinatal period associated with genital, large bowel, urinary, cardiac or central nervous system defects along with other VRDs such as bladder exstrophy, cyclopia/holoprosencephaly and acardia-acephalus. Antenatal diagnosis of sirenomelia by ultrasound is often impaired by oligohydramnios resulting from the frequently associated bilateral renal a/dysgenesis. A case report describes a live birth by normal vaginal delivery presenting with a single midline limb, two feet and absence of external genitalia/anal orifice. Antenatal ultrasound scans revealed moderate to severe oligohydramnios, and poorly visualised foetal kidneys. This study describes the clinical presentation, associated malformations, and classification of sirenomelia.