The two most common diseases that cause urinary retention are benign prostatic hyperplasia and urethral stricture. Long-term urinary retention can easily cause bacterial multiplication secondary to urinary tract infection, and the infection is difficult to cure and easy to recur, which will accelerate the damage of kidney function. So the serious complication of urinary retention is secondary urinary tract infection, and also because of long-term urinary retention, the internal pressure of the bladder increases, urine reflux from the ureter causes hydronephrosis, making the parenchyma of the kidney compressed causing destruction of kidney function, leading to renal insufficiency. Chronic renal failure requires dialysis and kidney replacement. The fastest solution to urinary retention is indwelling catheterization, which should be treated accordingly to the cause.