Catheterization is the insertion of a catheter through the urethra into the bladder to draw out urine. The purpose of catheterization is mainly for the following: to draw out uncontaminated urine specimens directly from the bladder, to do bacterial cultures to measure the bladder volume, pressure and detect the amount of residual urine, and to identify urinary incontinence and urinary retention in order to assist in the diagnosis; to release urine for the patients who have retention of urine in order to alleviate the pain; and to catheterize the patients before the surgery of the organs in the pelvic cavity, in order to empty the bladder to avoid accidental injuries during the surgery. The most common reason for inserting urinary catheter in the elderly is mainly because of urinary retention, so it is necessary to insert a catheter; in addition, the most serious is because of urinary incontinence or perineal injuries, keep a catheter to keep the local clean and clean; after some urinary system surgery, in order to promote the recovery of bladder function and incision healing, it is also necessary to retain a catheter, to save the patient from shock or dying, and to correctly record the specific gravity of urine volume, in order to observe the renal function condition. So inserting a catheter does not determine how long the old man will live, if it is just ordinary urinary retention, it has no effect on life. However, if the patient has been comatose in shock, is dying patients, at this time the insertion of urinary catheter situation, it may mean that this patient is already dying patients, but the specific can live for how long will depend on the patient’s own lesions and the overall effect of treatment. Whether or not a urinary catheter is inserted does not fully reflect the severity of the disease and the patient’s life expectancy.