The success of a colonoscopy is closely linked to good bowel preparation, with poor bowel prep often resulting in missed precancerous lesions, according to new consensus guidelines released by the U.S. Multi-Society Task force on Colorectal Cancer. Additionally, poor bowel cleansing can result in increased costs related to early repeat procedures. Up to 20 to 25 percent of all colonoscopies are reported to have an inadequate bowel preparation.
"When prescribing bowel preparation for their patients, health-care professionals need to be aware of medical factors that increase the risk of inadequate preparation, as well as nonmedical factors that may predict poor compliance with instructions," according to David A. Johnson, MD, lead author of the guidelines, professor of internal medicine and chief of the division of gastroenterology, Eastern Virginia Medical School, Norfolk. "Gastroenterologists should use this information when determining whether to use a more effective or aggressive bowel preparation regimen, as well as the level of patient education needed about the prep."
Effect of inadequate preparation on polyp/adenoma detection and recommended follow-up intervals
- Inadequate preparation of the colon is associated with reduced adenoma detection rates.
Preliminary assessment of prep quality should be made. If the indication is screening or surveillance and the preparation is inadequate to allow polyp detection greater than 5 mm, the procedure should be either terminated and rescheduled, or an attempt should be made at additional bowel cleansing strategies that can be delivered without cancelling the procedure that day.
If the colonoscopy is complete to the cecum, and the preparation ultimately is deemed inadequate, then the examination should be repeated, generally with a more aggressive preparation regimen, within one year; intervals shorter than one year are indicated when advanced neoplasia is detected and there is inadequate preparation.
If the preparation is deemed adequate and the colonoscopy is completed, then the guideline recommendations for screening or surveillance should be followed.
Dosing and timing of colon cleansing regimens
- Use of a split-dose bowel cleansing regimen is strongly recommended for elective colonoscopy, meaning roughly half of the bowel cleansing dose is given the day of the colonoscopy.
- The second dose of split preparation ideally should begin four to six hours before the time of colonoscopy with completion of the last dose at least two hours before the procedure time.
- During a split-dose bowel cleansing regimen, diet recommendations can include either low-residue or full liquids until the evening on the day before colonoscopy.
- A same-day regimen is an acceptable alternative to split dosing, especially for patients undergoing an afternoon examination.
Usefulness of patient education and navigators for optimizing preparation results
The U.S. Multi-Society Task Force on Colorectal Cancer is composed of gastroenterology specialists with a special interest in colorectal cancer, representing the American Gastroenterological Association, the American College of Gastroenterology and the American Society for Gastrointestinal Endoscopy.
The consensus statement, "Optimizing Adequacy of Bowel Cleansing for Colonoscopy: Recommendations from the US Multi-Society Task Force on Colorectal Cancer," is published in Gastroenterology, the official journal of the AGA Institute; American Journal of Gastroenterology, the official journal of ACG; and GIE: Gastrointestinal Endoscopy, the official journal of ASGE.