Antenatally diagnosed hydronephrosis: a practical guide to management

Abstract

Neonatal hydronephrosis consistent with a pelviureteric junction obstruction is the commonest urinary tract anomaly diagnosed by antenatal ultrasonography. There is however, no imaging modality that prospectively and reliably predicts an 'obstruction' which would benefit from surgery from one that will remain stable or even resolve spontaneously. Antenatal ultrasonography has led to a predictable increase in the incidence of urinary tract anomalies, the commonest of which is hydronephrosis. Postnatal investigations will clarify whether this dilatation is due to an obstruction, reflux or duplex kidneys. The majority of antenatally diagnosed renal tract anomalies are found postnatally to be a simple hydronephrosis consistent with a radiological diagnosis of a pelviureteric junction obstruction. However, unlike the classical presentation, the present population of neonates are largely asymptomatic with no abnormal physical signs. At present there is still no universally accepted gold standard for prospectively identifying the population at risk of functional deterioration, urinary tract infection, pain etc. The challenge posed by maternal ultrasonography is of finding parameters that will prospectively differentiate between an 'obstructed' hydronephrosis and a dilatation which is inconsequential to the well being of the child.