Ankle arthroscopy usually requires a catheter because the anesthesia for ankle arthroscopy is usually intrathecal anesthesia and the duration of the surgery is unpredictable, so a catheter is required. Generally, whether a catheter is required for a surgery depends on the anesthesia method, the site of the surgery, the duration of the surgery and the severity of the disease. 1. Anesthesia: Generally speaking, general anesthesia and some epidural anesthesia need to insert a catheter because the nerves controlling bladder urination will be blocked after anesthesia, which may lead to urinary retention if a catheter is not inserted. 2. The site of surgery: urethra, prostate, bladder and ureter surgery generally need to insert a catheter. 3. Duration of surgery: Generally speaking, surgery lasting more than one hour requires a catheter to prevent excessive accumulation of urine in the bladder, which may cause discomfort, stimulate nervousness and increase the risk of infection. 4. The severity of the disease: For patients with serious conditions, all surgeries generally require the insertion of a catheter, because it is necessary to calculate the patient’s in and out volume through the amount of urine, so as to determine the patient’s blood perfusion and renal function level. Therefore, if a catheter is needed for ankle arthroscopy, it is recommended to follow the doctor’s instructions and not to make a blind decision on your own to avoid a delay in your condition.