Prenatally diagnosed pelviureteric junction obstruction: a benign condition?

Renal function in neonates with antenatally diagnosed pelviureteric obstruction is usually well preserved and rarely deteriorates in the short term. To assess if function is maintained in the medium term, and, where not, if any factors are predictive of deterioration, the authors reviewed their cases (1985 to 1992) of antenatally diagnosed unilateral pelviureteric obstruction with renographic confirmation (type II and IIIb curves). Initial renographic assessment was performed at 1 to 3 months. Among the 160 cases, initial differential function exceeded 40% in 140 (87.5%), and these were managed expectantly with renographic follow-up, usually at 24, 48, and 72 months of age. The 20 patients with reduced differential function underwent early intervention (pyeloplasty, or trial of nephrostomy drainage in those with very poor function). Follow-up in those managed expectantly showed good differential function in 135 (96.5%), despite persistence of renographic obstruction in two thirds of the cases, more than half of which have had renographic follow-up beyond 4 years. Differential function decreased to below 40% in five patients (3.5%); this was not related to the type of renographic curve or severity of the hydronephrosis. The natural history of antenatally diagnosed pelviureteric obstruction continues to appear benign, and it may differ from that in older children who present clinically.