Reflex anuria from unilateral ureteral obstruction.

Renal function is usually normal or only marginally affected in patients with unilateral ureteral obstruction due to the vicarious function of the contralateral kidney. Few reports exist in which unilateral renal obstruction is associated with anuria (reflex anuria, RA) and acute renal failure. We report the clinical case of a female patient who was referred to the emergency department due to anuria of 72 h duration and acute renal failure (serum creatinine 9 mg/dl) associated with several episodes of violent right flank pain with hematuria following extracorporeal shock wave lithotripsy (ESWL). A few weeks before ESWL, urography showed a 2-cm stone located in the right pelvis whilst the left kidney was functionally normal. On admission, renal ultrasound documented a normal left kidney, whilst the right pelvis was hydronephrotic and there were two indwelling stones at the right pyeloureteral junction. After the patient passed a urinary stone, diuresis restarted and acute renal failure was resolved. Thereafter, urography confirmed that the left kidney, the left ureter and bladder were functionally and morphologically normal. RA with acute renal failure has been so scarcely documented that it is considered to be legend by many clinicians. Major textbooks do not discuss RA with acute renal failure. Vascular or ureteral spasm related in part to a peculiar hyperexcitability of the autonomic nervous system may explain RA. We suggest that nephrologists should always consider RA when evaluating acute renal failure. On the other hand, RA might be relatively common and we cannot rule out that only the most severe and/or better-documented cases have been reported in the medical literature.