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 before a medical procedure such as a colonoscopy. When oral laxatives are not indicated or 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 colon sections.
The colon reacts to that sudden expansion with general contractions, peristalsis , propelling its contents toward the rectum. Soapsuds enema is a frequently used synonym for a large volume enema although soap is not necessary for effectiveness. A large volume enema may be used in a home setting to relieve occasional constipation, although medical care may be required for recurring or severe cases of constipation. Plain water can be used, 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 retention period is desired, such as to soften an impaction. Castile soap is commonly added because its irritation of the colon's lining increases the defecation urgency.
