Prenatal diagnosis of sirenomelia with bilateral hydrocephalus: report of a previously undocumented form of VACTERL-H association.

Sirenomelia represents a severe developmental field defect of the posterior axis caudal blastema, resulting in partial or complete fusion of the lower limb buds. The VATER association is a combination of morphological defects including vertebral defects, anal atresia, tracheoesophageal fistula, esophageal atresia, radial and renal anomalies. The VACTERL-H association is a rare expanded form of the VATER association that includes cardiac defects, limb defects, and hydrocephalus. It has been suggested that the VATER association may represent a less severe form of sirenomelia. In this report, we document a case in which prenatal ultrasonography detected simultaneously occurring sirenomelia and hydrocephalus. Postmortem radiography and autopsy findings confirmed the prenatal diagnosis. To our knowledge, this is the first report of prenatal diagnosis of a fetus with these two abnormalities. This report supports the hypothesis that VATER association, VACTERL-H association, and sirenomelia may represent pathophysiologically related entities.