Abstract
Caudal duplication syndrome is a rare entity in which structures derived from the embryonic cloaca and notochord are duplicated to various extents. Its prevalence at birth is less than 1 per 100,000. The term caudal duplication encompasses a spectrum of anomalies and is often used to describe incomplete separation of monovular twins or referred to as part of the spectrum of anomalies associated with conjoined twinning. It usually includes multiple rare malformations and duplications of distal organs derived from the hindgut, neural tube, and caudal mesoderm. It was postulated that the disorder is related to misexpression of one or more of the distal HOX genes, potentially HOX10 or HOX11, leading to abnormal proliferation of caudal mesenchyme. The malformations are usually diagnosed by anomaly scan in the second trimester. Here we report the case of a baby presenting on the first day of life with complete duplication of caudal structures below the dorsolumbar level.