The timing of catheter removal for colorectal cancer surgery patients is related to two aspects: site and age, which I explain below. First of all, the site: the surgical site of rectal cancer is different from that of colon cancer. Patients with rectal cancer should be cautious in removing urinary catheters. This is because rectal cancer surgery requires “opening” the pelvic cavity, which may irritate, strain or damage the nerves in the pelvic cavity and greatly affect the patient’s urination; whereas colon cancer surgery is performed in the abdominal cavity, so there is no concern about this when removing the urinary catheter. Secondly, age: older patients, due to physical reasons (prostate enlargement, mobility problems, etc.), may have problems such as urinary retention if the urinary catheter is removed at an early stage; if the patient is younger and does not have bladder paralysis, etc., it can be removed on the same day after surgery. If the urinary catheter has been left in place for a period of time, before removal, it is necessary to do “training”, that is, to clamp the urinary catheter for a period of time, and then cancel the clamp when the patient feels “suffocated”, so as to train the patient’s urinary reflex and avoid blind removal of the urinary catheter that leads to urinary retention and other dangerous situations. This can train the patient’s urinary reflex and prevent the blind removal of the urinary catheter from causing dangerous situations such as urinary retention.