Normally there is no danger in inserting a urinary catheter, but prolonged insertion of a urinary catheter may cause difficulty in urination, formation of a small bladder, and urinary tract infections. 1. Difficulty in urination: Due to the long-term retention of the urinary catheter, the forced urethral muscle is in a state of continuous contraction. If the catheter is suddenly withdrawn, the function of the urethral muscle cannot be restored and normal micturition reflexes cannot be performed, which may lead to difficulty in urination. 2. Formation of a small bladder: If the patient is in the state of inserting a urinary catheter for a long time, the bladder may be in a state of emptiness. With the passage of time, the bladder capacity will be drastically reduced, and eventually symptoms of atrophy will appear, which cannot be controlled autonomously, such as the inability to hold urine and other problems. 3. Urethritis: As a result of prolonged indwelling urinary catheterization, some secretions in the urethra cannot be discharged, which can lead to bacterial infection. Bacteria may enter the urethra or bladder retrogradely through the catheter, leading to urethritis. The retention and removal of catheters must be done under the guidance of a physician. If an infection has occurred, you need to seek professional medical treatment as soon as possible.