The value of renal scintigraphy during controlled diuresis in children with hydronephrosis.

Dynamic renal scintigraphy (DRS) during controlled diuresis is the method of choice to diagnose the functional relevance of urinary tract obstruction in children with sonographically demonstrated hydronephrosis. However, there are no commonly accepted scintigraphic criteria for surgical intervention. On the basis of our findings, we propose four stages of washout (WO) of tracer following diuresis: in stage I, WO>50%, neither further diagnosis nor intervention is necessary; in stage II, 50%>/=WO>/=12%, repetition of DRS is advised within 3-4 months; and in stage III, 12%>WO>/=5%, DRS should be repeated within 1-2 months. Only in stage IV, WO<5%, should surgery be done immediately. This procedure reduces surgical interventions by 50% without increasing the risk of residual renal damage.