Acute Urinary Retention

The Clogged Sink with a Backup Alarm

Imagine your bladder is a sink basin and your urethra is the drain pipe. Water (urine) flows in continuously from the faucet (kidneys) through the hose (ureters). Normally, the drain valve (sphincters) opens when you decide to empty the sink, and water flows out. But if the drain pipe gets clogged (enlarged prostate, stricture, stone) or the drain valve motor breaks (nerve damage, anticholinergic drugs), water fills the basin past its normal level. The backed-up water pushes backward through the inlet hoses (ureters) into the faucet system (kidneys), swelling the pipes and reducing water pressure in the faucet itself. The water level rises so high the basin hurts, but no water comes out when you try. The longer the clog stays, the more the faucet system swells and weakens. Only draining the basin (catheter) or unclogging the pipe (surgery) stops the backup and saves the faucet.