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"What is an enema?"

ZocdocAnswersWhat is an enema?


My grandfather is elderly, and he has trouble with his colon. The doctor just recommended that he get an enema. What does this mean? How do enemas work, and what are they supposed to do?


A basic review of anatomy is helpful to start. The lower half of the gastrointestinal (GI) tract consists of the small intestine, where food is digested and nutrients are absorbed into the bloodstream, and the large intestine, where waste material collects. The large intestine is also called the colon and has several parts: the ascending part is on the right side of the abdomen, the transverse part runs horizontally across the abdomen, and the descending part runs down the left side of the abdomen. The descending colon then continues to form the sigmoid colon, which connects to the rectum, which connects to the outside through the anus. An enema is an infusion of liquid through the anus, which travels up usually to the level of the descending (left-sided) colon. There are several reasons that a patient would need an enema, and there are many liquids that can be used for the enema. One common reason is to treat constipation. When a patient is constipated, his or her stool has been sitting in the colon for a prolonged period of time. As the stool sits in the colon, water moves out of the stool and into the nearby colonic blood vessels, resulting in a hard, dry stool that is difficult or painful to pass. The process of receiving an enema can be done by the patient alone (depending on his or her ability to reach around to their bottom), or with the aid of a nurse or family member. When treating constipation, the enema fluid can be sodium phosphate (Fleet's enema), mineral oil, tap water, soap suds, or molasses. A doctor will advise the patient on the most appropriate type of fluid, since patients with certain medical problems like kidney disease or blood electrolyte problems should not use certain enema fluids. The fluid comes in a bottle with a tapered end that is inserted into the anus, and the fluid is slowly squeezed in. The patient may feel a sensation of needing to have a bowel movement. It is important to try to hold the fluid in the rectum for at least several minutes to allow it to work. This can be done by squeezing the buttocks together. While the fluid is in the rectum and colon, the stool becomes lubricated and softens, and the patient gets the urge to pass a bowel movement. The enema fluid and the stool are then released together through the anus, often as a large, loose bowel movement. Other uses for enemas include preparation for a colonoscopy or sigmoidoscopy, where the doctor uses a tube-like camera to look inside the colon; in preparation for a radiology test to look at the colon size (barium enema); and some medications for colon inflammation can be given as enemas. It is important to check with your doctor about the safety of using an enema before receiving one.

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