.]]An enema (plural enemata or enemas) is the procedure of introducing liquids into the rectum and colon via the anus. Enemas can be carried out for medical reasons (as a treatment for constipation), as a remedy for encopresis, as part of alternative health therapies, and also for erotic purposes, particularly as part of BDSM activities. In earlier times, they were often known as clysters, and were probably used more frequently than at present.
Medical usage
The main medical usages of enemas are:
As a bowel stimulant, not unlike a laxative -- the main difference being that laxatives are commonly thought of as orally administered while enemas are administered directly into the rectum, and thereafter, into the colon. When the enema injection into the rectum is complete, and after a set "holding time," the patient expels feces along with the enema in the bedpan or toilet.
Enemas may also be used to relieve constipation and fecal impaction, although in many professional health-c
Source:
http://en.wikipedia.org/wiki/Enema