Severe fetal hydronephrosis: the added value of associated congenital anomalies of the kidneys and urinary tract (CAKUT) in the prediction of postnatal outcome.

Severe fetal hydronephrosis has a wide postnatal clinical spectrum, which is mainly influenced by the presence of associated sonographic CAKUT findings. These clinical data have biological relevance: a genetic or environmental defect that influences multiple renal developmental processes leads to hydronephrosis but also to concomitant malformations (CAKUT) and critically influences renal prognosis. A more selective abnormal developmental process that results in isolated enlarged pelvis even to a severe extent has less influence on renal prognosis.