CLINICAL RELEVANCE AND IMPLICATIONS OF ANTENATAL HYDRONEPHROSIS

Detailed antenatal sonography was performed on 18 766 pregnant women b etween 1990 and 1994. Antenatal hydronephrosis, defined as an antero-p osterior diameter of the renal pelvis (APPD) greater than 5 mm, was de tected in 100 cases (0.59%). Sixty four infants had postnatal hydronep hrosis at one and/or six weeks after delivery; 21 of these had urologi cal anomalies. Twelve infants had vesico-ureteric reflux. In all reflu xing units the APPD of the renal pelvis was less than 10 mm. Three pat ients had obstruction at the pelviureteric junction (PUJ); all require d surgery. Vesico-ureteric reflux is emerging as the most common urolo gical finding in infants with antenatal hydronephrosis and is likely t o be missed if kidneys with APPD of less than 10 mm are not further in vestigated. In contrast, pelvi-ureteric junction obstruction may be ov erdiagnosed, based only on drainage patterns of dynamic renogram studi es.