Caudal Regression Syndrome and Sacral Agenesis

Abstract

The term “syndrome of caudal regression” was first used by Duhamel to describe a spectrum ranging from simple sacral agenesis to severe lower limb anomalies including fusion as “sirenomelia,” often with imperforate anus and major malformations of the anus and rectum, omphalocele, and anomalies of the genitourinary system, but sacrococcygeal agenesis or hypoplasia was the constant feature, but partial or complete absence of the sacral and coccygeal bones was first described by Hohl in 1852; in 1857, over the next 100 years, about 50 additional cases were published singly or in small series. In 1959, Blumel and colleagues reported 50 more cases, many of which included other malformations such as meningoceles, anal and bowel anomalies, and abnormalities of the lower limbs often associated with dysfunction of the bowel and urinary bladder. Sirenomelia is also a syndrome of sacral agenesis in which the fused lower extremities cause the fetus to resemble a mermaid.