Fetal hydronephrosis, a one year follow up.

Objective: To determine the underlying urological anomalies and the outcome during the first year, in babies with antenatally diagnosed hydronephrosis.

Methods: A prospective descriptive study. Methods: Southlands and Worthing Hospitals, Worthing, UK. Methods: From January 1991 to December 1992, in the Worthing District Health Region, UK all babies with hydronephrosis persisting postnatally (69) were prospectively assessed for renal growth and function, general well-being, and complications if any. The diagnoses, treatment and complications occurring during the first year were analysed.

Results: Of the 69 babies 4 were lost to follow up. The 65 fetuses assessed had the following underlying causes: transient in utero hydronephrosis 34 (52.3%), idiopathic hydronephrosis 9 (13.8%), isolated vesico-ureteric reflux 5 (7.6%), vesico-ureteric reflux with other urological abnormalities 2 (3.1%), pelvi-ureteric junction obstruction 2 (3.1%), equivocal pelvi-ureteric junction obstruction/idiopathic hydronephrosis 4 (6.2%), multicystic dysplastic kidney 4 (6.2%), polycystic kidneys 1 (1.5%) and patulous extrarenal pelvis 4 (6.2%). During one year of follow up 4 (6%) of babies needed surgical intervention and further 6 (9%) needed antibiotic prophylaxis.

Conclusions: The majority of fetal hydronephroses is were self-limiting or benign. Vesico-ureteric reflux was the commonest urological abnormality. 23 (33%) apparently normal neonates detected on prenatal screening needed aggressive management or close monitoring.