Although it is rare, some women get an infection each time they have sex. Waiting too long to urinate can also result in urinary tract infections. The bladder is a muscle that stretches to hold urine and contracts to expel it. If you go for hours without urinating, the bladder muscle is stretched beyond its normal capacity. Overfilling the bladder like this gradually weakens the muscle so that it can't contract with enough force to expel all of the urine it holds.
Some urine remains in the bladder after urination.
Any time this happens, the risk of a urinary tract infection increases. Symptoms Symptoms of urinary tract infections can come on suddenly. As urine is released, a woman will feel a sharp pain or burning sensation in the urethra. Very little urine is eliminated and the urine may be tinged with blood. Soreness may occur in the lower abdomen, in the back, or in the sides.