Clean catheterization, also known as intermittent catheterization, is a method of catheterization without an indwelling catheter that can be performed by non-medical staff (patient, relative or companion) for a predetermined period of time to reduce the patient’s dependence on medical staff and to increase the patient’s independence in life. This procedure is repeated several times a day and is determined by the patient’s urinary function. The purpose is that by catheterizing the bladder at regular intervals or at the right time when bladder distention is detected can empty the bladder and avoid excessive bladder distention, thus reducing complications, such as reducing the rate of infection, reducing the incidence of urinary stones, promoting early recovery of the forceps, avoiding bladder contracture, reducing complications of the penis and scrotum (such as orchitis or epididymitis), and reducing autonomic reflex disorders. It can be done to keep the bladder properly filled and emptied, and is also the basis for bladder function training. Contraindications: 1, severe injury or infection of the urethra, and pressure sores in the urethra. 2.The patient is confused or uncooperative. 3.Receiving large amounts of fluids. 4, Systemic infection or extreme immune deficiency. 5.There is a significant bleeding tendency. 6, Significant prostate hypertrophy or tumor. Operation steps: 1. Clean the catheter with 0.9% sodium chloride solution or other medical disinfectant without mucosal irritation (Neosporin, chlorhexidine, etc.) for backup. 2. Wash the patient’s perineum locally with soap or cleaning solution. Wash the operator’s hands (can be the patient or the escort). 3.Insert the catheter into the urethra with the hand and push it in slowly until the urine is discharged from the catheter. Male patients pay attention to the direction of the urethral opening towards the abdomen to avoid damage to the urethral isthmus. A lubricant (e.g. paraffin oil) can be applied to the outside of the catheter before insertion to reduce insertion resistance. 4.Remove the catheter immediately after the catheterization is completed. 5.Wash the catheter with water after removal, and then put it into medical disinfectant solution without mucous membrane irritation or 0.9% sodium chloride solution for storage. Boiling disinfection can also be used. 6.Use frequency If the patient is completely unable to urinate on his own, the use frequency can be 3~4 times/day; if he can partially urinate, the use frequency can be 1~2 times/day. The urine from each catheterization is usually about 400ml (physiological bladder capacity). Clean catheterization can be stopped when the residual urine is less than 80 to 100ml. Precautions: 1. Patients must develop a system of regular and quantitative drinking and regular urination in order to choose the timing of catheterization reasonably. 2.Patients usually do not need to take in more than 2000ml of water daily and keep the urine volume around 800~1000ml/d. 3.Although the catheter does not emphasize strict sterilization, adequate cleaning and reasonable preservation should be emphasized. 4.The insertion action must be gentle and non-violent to avoid urethral injury, especially for male patients.