An enema refers to the means by which liquids are introduced into the rectum and colon via the anus. When a large volume of water is injected into the rectum it causes an expansion of the intestinal tract. The bloating and discomfort that this entails leads to the lower intestinal tract emptying itself.
Enemas are usually administered for medical reasons as a remedy for constipation and in other alternative health treatments. It is also used for purposes of recreation and for erotic purposes such as anal sex.
Enemas are used as a laxative; instead of an oral administration it is directly administered to the rectum and from there to the colon. After some time, the patient expels the enema along with the faeces and the rectum is clean. Enemas have now been replaced by laxatives and suppositories in the U.S although still in use in several other countries. Since their primary use hinges around bowel stimulation, they are not done at home. Enemas are usually a mixture of water and either sodium bicarbonate or mild hand soap. A solution of buffered sodium phosphate is a popular enema as it is capable of drawing water from the blood stream into the colon. This helps as the colon is usually irritated from the cramping, and aids in the expulsion of waste. Mineral oil is sometimes used as a constituent of an enema as it softens the faeces and functions as a lubricant. However, it may be unpleasant for the patient as there are chances of seepage from the anus for the next 24 hours leading to uneasiness, and soiled undergarments. An isotonic saline solution is also used, as it has a neutral concentration gradient and hence does not leech the body of its necessary electrolytes. Unlike a phosphate based enema, it does not draw water from the bloodstream. Occasionally antiemetics which are given to reduce nausea cannot be administered orally and are given as an enema. Medication for arthritis, muscular degeneration and even cancer are also given as an enema at times. Colitis, intestinal obstructions, intussusceptions in children are some conditions for which the procedure is commonly performed.
Enemas have to be administrated carefully as there are risks of the rectal tissue or bowel rupturing. Even slight tears are dangerous as it may lead to an infection from the bacteria found in faeces. Enemas are not advisable for people who have had bowel surgery, hemorrhoids or tumors in the rectal area.