Indications and techniques for bowel preparation in colorectal cancer.

A satisfactory bowel preparation is essential for adequate double contrast barium enema and colonoscopy. Efficient preparation is also important for reducing the risk of anastomotic dehiscence and sepsis in elective colorectal surgery. Traditional preparation by starvation, purgation and enemas is time consuming, unpleasant for patients, and in our experience results in a satisfactory preparation in only 23% of patients. Elemental diets are inefficient when used for only five days. Whole bowel irrigation with a nasogastric tube enables patients to be in hospital for only one day before operation and provides a satisfactory result in 61% of patients. Whole bowel irrigation is not recommended for stenosing tumours. Irrigation with saline causes sodium and water retention and the use of a balanced electrolyte solution (eg, Ringer's lactate) reduces the risk of these side effects. Oral mannitol has become popular but in our experience results in a satisfactory preparation in only 41% of patients. Mannitol is fermented by E coli to potentially explosive gas mixtures unless oral antimicrobials (neomycin and metronidazole) are used immediately before operation. Polyethylene glycol also causes osmotic catharsis without the risk of explosion. We currently favour nasogastric irrigation with polyethylene glycol and a balanced electrolyte solution, but there is still a place for traditional preparation over five days for patients with stenosing tumours of the left colon.