Enema can stimulate intestinal peristalsis, speed up the excretion of feces, has the effect of cooling down and reducing the absorption of toxins in the intestine, and can be used as a preoperative examination or a treatment for some diseases. How long it takes to defecate after enema depends on the purpose, the time is 10-60min. 1.Large amount of unreserved enema: To achieve the purpose of relieving constipation, expelling flatulence or hyperthermia to cool down and cleanse the intestine, patients are generally instructed to lie flat for 5-10mim before defecating; 2.Small amount of unreserved enema: Patients are recommended to retain 10-20min before defecating, so that the enema solution can be in full contact with feces to soften and Lubricate the stool, better relieve constipation and reduce abdominal distension, for the elderly and frail, pregnant women and children; 3. Retained enema: its purpose is hypnotic, sedative and treatment of intestinal diseases, patients are generally instructed to retain the solution for at least 60min before defecation. This helps the solution to be more fully absorbed, so that the therapeutic effect is better. The enema needs to be done in a hip-high, head-low position to avoid the flow of enema fluid from the anus and keep it in the intestine for a longer period of time to achieve effective cleansing and therapeutic effects.