The most common cause of postrenal failure is:
A. A clogged urinary catheterRenal failure can be classified as prerenal failure, intrinsic renal failure, and postrenal failure. Postrenal failure, or obstructive renal failure, should always be considered when low urine output (oliguria) or anuria occurs. The most common cause is a misplaced or clogged urinary catheter. Other, less common causes to consider are unintentional ligation or transection of ureters during a difficult surgical dissection ( eg, colon resection for diverticular disease) or a large retroperitoneal hematoma ( eg, ruptured aortic aneurysm).