Obstructive Uropathy

Obstructive uropathy is a blockage anywhere along the urinary outflow tract—from the renal pelvis through the ureter, bladder, or urethra. Urine continues to form behind the blockage, so pressure builds upstream. The result is urinary stasis, dilation of the collecting system (hydronephrosis), reduced filtration, and, if the obstruction continues, progressive renal parenchymal injury. The location and completeness of the blockage shape the presentation. A urethral or bladder outlet obstruction may produce suprapubic fullness, hesitancy, a weak stream, overflow dribbling, or inability to void. A ureteral obstruction more often causes flank pain and renal tenderness. A unilateral obstruction may leave total urine output apparently normal because the opposite kidney continues to function; normal output therefore does not exclude obstruction. Bilateral obstruction, or obstruction in a person with a solitary functioning kidney, can reduce filtration quickly and cause acute kidney injury. Stagnant urine also provides a setting for bacterial growth. Fever, rigors, hypotension, or altered mental status in a patient with suspected obstruction suggests an infected, poorly drained urinary system—not an uncomplicated urinary tract infection. Infection plus obstruction can deteriorate rapidly because...