Nondilated obstructive uropathy: percutaneous nephrostomy performed to reverse renal failure.

Ureteral obstruction can lead to renal failure without involving detectable dilatation of the calyces, renal pelvis, or ureter proximal to the obstruction. This phenomenon was noted in seven patients who had clinical obstruction that we were not able to diagnose using computed tomography (CT) or ultrasonography (US). These patients underwent percutaneous nephrostomy (PCN), which resulted in brisk diuresis and improved renal function. We obtained an accompanying antegrade urogram in these cases, which demonstrated the level of obstruction and indicated that dilatation of the collecting system was minimal or not present. When obstructive uropathy is suspected, we believe it is essential to consider performing PCN to evaluate and potentially reverse renal failure, even when CT and US scanning do not demonstrate obstruction.