Non-dilated urinary tract obstruction

To describe the occurrence of obstructive uropathy in the absence of dilatation of the urinary tract.

Five cases of non-dilated obstructive nephropathy are described. All patients were uraemic on presentation. Obstruction was caused by retroperitoneal malignancy in two patients and uric acid lithiasis in the remaining three. All patients had at least one ultrasound examination. Isotope renography and computed tomography were performed in three and four patients respectively. None of these imaging techniques suggested obstruction in any of the cases. Radionuclide scans were characterised by unusually poor perfusion and parenchymal phase images.

An immediate diuresis and a rapid return of normal renal function occurred after relief of the obstruction in all cases.

The absence of dilatation in obstructive nephropathy is uncommon but may be responsible for delayed diagnosis and management of a readily treatable cause of acute renal failure.