Post-natal management of antenatally detected, bilateral hydronephrosis.

26 children, with antenatally detected, isolated, bilateral hydronephrosis (thus consistent with pelvi-ureteric junction obstruction), were investigated for up to 7 years. The aim was to avoid operation. 34 kidneys were never operated on. Despite initially often severe hydronephrosis and poor isotope wash-out on the renogram, half of the kidneys improved or even normalized during follow-up. The final glomerular filtration rate (GFR) was always normal or almost normal. 18 kidneys came to surgery, because of poor filtration, symptoms or social reasons. At the end of the follow-up, GFR was normal in all but 2 kidneys. In a subgroup of the kidneys, with initially severe reduction in filtration, half were operated on and half were not; at the end, the GFR was normal in all of the non-operated kidneys (and in all but 1 of the operated kidneys). Total GFR was at the end normal or almost normal also in the children with persistingly filtration-reduced kidneys (always unilaterally), because of compensation by the contralateral, although hydronephrotic kidney. Thus, in this study the renographic parameters were not very helpful in predicting the prognosis. There was no consistent difference between operative and non-operative treatments on final filtration. Also hydronephrotic kidneys possessed a substantial capacity for contralateral compensation. It is concluded that the initial approach to bilateral, antenatally diagnosed hydronephrosis may safely be non-operative. This allows time for the clear expression of sustained impairment of renal filtration requiring surgical intervention.