Enema is a method of directly injecting a certain amount of solution into rectum and colon to stimulate colon and rectal peristalsis to cause defecation. Enema is the most commonly used treatment for patients with rectal fecal impaction, which makes the fecal matter easy to be discharged after softening. Enema can also be used to help constipation patients treated by biofeedback, because before establishing this defecation behavior, it is necessary to eliminate the fecal blocks in the anorectum. The enema method is to insert a tube into the anus, 3 ~ 5 cm deep, and then slowly input the liquid. Enema should not be used for a long time to treat constipation. This is a temporary measure. The liquid used for enema is generally normal saline, and the temperature should be controlled at 39 ~ 40℃. Sometimes mineral oil such as magnesium sulfate laxative or glycerin can be used, and it is best not to use soapy water, because alkaline water can stimulate intestinal mucosa.

Short-term intermittent enema has little effect on the whole body and few adverse reactions. It is a good method to relieve constipation and can be used for acute constipation (such as acute fecal impaction). Sometimes this method can also be used to stimulate the rectum to re-establish the rectal defecation reflex, which can be used for the early treatment of some constipation patients. Enema therapy is also the basic therapy for treating constipation in children, which is often used to relieve constipation in children with idiopathic constipation or Hirschsprung's disease. For those patients with severe constipation who are still ineffective after dietotherapy and oral laxatives, enema is often the last resort. In addition, frequent enema can produce dependence and should be paid attention to.

Long-term use of enema to relieve constipation is harmful to human body, especially long-term use of soapy water enema will cause colitis, which is related to the alkaline effect of soap and the toxicity of long-chain fatty acids. In addition, complications related to enema include allergy, diarrhea and dehydration, and few deaths have been reported. Therefore, it is very important for patients to correctly grasp the indications and methods of enema.