An enema , also known as a clyster , is the rectal administration of a fluid by injection into the lower bowel via the anus. In standard medicine, the most frequent uses of enemas are to relieve constipation and for bowel cleansing before a medical examination or procedure; [ 5 ] also, they are employed as a lower gastrointestinal series also called a barium enema , [ 6 ] to treat traveler's diarrhea , [ 7 ] as a vehicle for the administration of food, water or medicine, as a stimulant to the general system, as a local application and, more rarely, as a means of reducing body temperature, [ 1 ] as treatment for encopresis , and as a form of rehydration therapy proctoclysis in patients for whom intravenous therapy is not applicable.
As bowel stimulants, enemas are employed for the same purposes as orally administered laxatives : to relieve constipation ; to treat fecal impaction ; to empty the colon prior to a medical procedure such as a colonoscopy. When oral laxatives are not indicated or are not sufficiently effective, enemas may be a sensible and necessary measure.
A large volume enema [ 10 ] can be given to cleanse as much of the colon as possible of feces. Such enemas' mechanism consists of the volume of the liquid causing a rapid expansion of the intestinal tract in conjunction with, in the case of certain solutions, irritation of the intestinal mucosa which stimulates peristalsis and lubricates the stool to encourage a bowel movement.
For emptying the entire colon as much as feasible [ 12 ] deeper and higher enemas are utilized to reach large sections of the colon. Soapsuds enema is a frequently used synonym for a large volume enema although soap is not necessary for effectivity. For relieving occasional constipation, a large volume enema may be used in a home setting, although for recurring or severe cases of constipation medical care may be required.
Plain water can be used, simply functioning mechanically to expand the colon, thus prompting evacuation. Normal saline is least irritating to the colon. Like plain water, it simply functions mechanically to expand the colon, but having a neutral concentration gradient, it neither draws electrolytes from the body, as happens with plain water, nor draws water into the colon, as occurs with phosphates. Thus, a salt water solution can be used when a longer period of retention is desired, such as to soften an impaction.
