If an acute obstruction is recognized and repaired quickly, then kidney damage may be minimal or reversible. If chronic unilateral obstruction is not relieved early, it could result in permanent damage to the kidney. Chronic unilateral obstruction, however, does not cause kidney insufficiency or failure because most patients have normal function from the other kidney, but chronic bilateral obstruction may lead to kidney failure because both kidneys may become damaged and fail to function even after repair.
Attribution: Avallain