Dipygus

Dipygus is a severe and extreme type of caudal duplication, a rare congenital disorder in which structures of the caudal region, the embryonic cloaca and the neural tube show a spectrum of abnormalities such as duplication and malformation, occurring at the caudal end of the body axis where it duplicates completely. The exact cause is unknown, though several theories implicate abnormal embryological development. Diagnosis is often made during the second trimester of prenatal development through anomaly scans or immediately after birth, though rare adulthood diagnoses have also been observed. Treatment depends on the range of symptoms present and ranges from conservative expectant management to resection of caudal tissue to restore normal function or appearance. As a rare congenital disorder its prevalence at birth is less than 1 per 100,000, with fewer than 100 cases reported worldwide, and the broader classification it falls under, caudal duplication syndrome, was named in 1993.