large volume enemas consist one pint to two quarts of warm water, sometimes with a mild soap added. A large volume enema works by expanding the colon, which causes peristalsis, i.e, contractions of the colon. Most individuals will have a bowel movement within 5 to 15 minutes of receiving a large volume enema.
Examples of small volume enemas are fleet phosphate enemas, which work by stimulating the colon and consist of approximately 4 ounces of solution. Mineral oil or vegetable Oil enemas are also given in small volume, usually 4 to 8 ounces. sorbitol is sometimes given rectally as a small volume enema, and is usually effective within 15 minutes, avoiding the gastric problems of oral administration.