Single umbilical artery and associated malformations in over 5500 autopsies: relevance for perinatal management.

With a birth prevalence rate of about 1%, single umbilical artery (SUA) is the most frequent of all congenital anomalies. It is recognizably associated with a variety of birth defects, but disagreement exists as to whether a SUA can predict an adverse perinatal outcome; disagreement also exists related to if, when present, other birth defects should be ruled out. The aims of the study were to estimate the association between SUA and other birth defects in a series of perinatal autopsies, to establish if preferential associations between SUA and certain birth defects exist, and to quantify the risks for other birth defects when a SUA is diagnosed. In a series of 5539 perinatal autopsies conducted at the Hospital Materno Infantil Ramón Sardá and the Private Laboratory of Perinatal Pathology, Buenos Aires, Argentina, the rate of each malformation (grouped by organ/system) associated with SUA and the risks of associated malformations were estimated. In this series of autopsies, the rate of SUA showed a 10-fold increase when other malformations were present. The risk for other malformations increased significantly, by a 3-fold to 9-fold measure, when a SUA was present. Urinary and gut anomalies showed a preferential association with SUA. The absence of other birth defects lowered the risk of chromosome anomalies associated with SUA in 56% (odds ratio  =  0.44). These results, obtained from a series of perinatal autopsies, are in agreement with most observations found in the literature, namely, high association rates between SUA and urinary and cardiovascular anomalies as well as a low risk for chromosome anomalies in SUA cases without other malformations.