Thus urine left in the bladder, which is known as post-void residual urine , may predispose a person to frequent UTIs, or urinary tract infections. Kidney damage can occur from frequent upper urinary tract infections. Infected urine can actually back up through the ureters into the kidneys if the exit is blocked by a contracted or tight sphincter. Bladder or kidney stone formation is another potential complication of incomplete emptying. Minute mineral particles normally expelled in urine may clump together to form stones which cannot be passed through urination.
Stones can further complicate normal voiding.
Frequent UTIs, kidney or bladder stone formation, and kidney damage all suggest a problem with chronic urinary retention. In the past, a technique called cred was sometimes taught to people with retention problems. It involved pushing down on the lower abdomen while voiding. It is now considered harmful. The pressure of cred often moves the urine up, not down.