Patients who undergo colonoscopy often view bowel preparation as worse than the actual procedure. But new multisociety guidance suggests that clinicians can help make prep easier for some patients.
Dietary changes the day before colonoscopy and a 2-L split-dose bowel preparation regimen may suffice for most patients at average risk for inadequate bowel preparation, according to updated recommendations from the U.S. Multi-Society Task Force on Colorectal Cancer (Am J Gastroenterol 2025;120[4]:738-764), the first since 2014.
“We can do things that are ... better tolerated by [average-risk] patients without sacrificing some of the effectiveness of these regimens,” said co–first author Brian Jacobson, MD, MPH, a gastroenterologist and the director of program development for gastroenterology at Massachusetts General Hospital, in Boston.
These liberalized regimens do not apply to patients with risk factors for inadequate prep, such as baseline constipation, medications that slow motility, and cirrhosis, Parkinson’s disease, dementia or diabetes, stressed the task force, made up of representatives of the American College of Gastroenterology, American Gastroenterological Association and American Society for Gastrointestinal Endoscopy. Such patients should undergo a regimen that begins three days earlier and uses higher purgative volumes and adjunctive bisacodyl, according to the task force.
The panel weighed evidence relating to 21 clinically relevant questions and issued consensus statements in the form of recommendations and key concepts. The guidance also includes tables with sample meals and purgative options. The guidance does not cover pediatric patients, flavorings, or the management of antithrombotic and antiplatelet medications.
Before Colonoscopy
In addition to verbal and written educational materials about preparation for patients, the new guidance recommends the use of patient navigation with either telephonic or—new since 2014—electronic messages.
For most average-risk patients, dietary restrictions need begin no sooner than the day before. As in 2014, diets as part of a split-dose regimen should be clear liquid or low-fiber/low-residue for breakfast and lunch.
A 2-L rather than 4-L prep now is suggested for ambulatory patients at low risk for inadequate prep. Whatever the volume, as in 2014, the authors recommend splitting the dose between the day before and the day of colonoscopy. Same-day prep before afternoon procedures for this patient population is still an option.
As before, no specific purgatives are recommended; the decision should weigh factors like patient preference, medical history, previous regimens, costs and safety.
During Colonoscopy
When there is concern about the adequacy of the prep, the task force suggests inserting the scope at least to the sigmoid before aborting the colonoscopy. Same-day salvage maneuvers for inadequate bowel prep, where feasible, are suggested.
The task force defines an adequate bowel prep as one that allows the endoscopist to assign an appropriate standard screening or surveillance interval. Adequacy, based on all colon segments, should be assessed after washing and suctioning.
They also now suggest routine use of irrigation pumps. Using oral simethicone as a routine adjunctive is now suggested for average-risk patients, too.
After Colonoscopy
The authors recommend tracking prep adequacy rates by both endoscopist and endoscopy unit; rates should be at least 90%, up from 85% suggested in 2014. Counts should include cancellations due to presumed inadequate prep.
If bowel prep is inadequate, a repeat procedure within 12 months for screening or surveillance is recommended, with modified prep instructions (tactics are suggested). Patients with alarm symptoms should undergo repeat prep and colonoscopy as soon as possible.
If, during a screening colonoscopy in a patient with no adenomas on index colonoscopy, prep is inadequate to visualize the ascending or transverse colon but adequate for the descending colon, sigmoid colon and rectum, then reconsidering screening options is reasonable. Patients may opt for a flexible sigmoidoscopy or recommended nonendoscopic screening such as a fecal immunochemical test or stool-based DNA testing within five years.
“If you feel someone did not have an adequate bowel preparation, you could schedule them again, but you could also use that as an opportunity to have a conversation with them about alternative screening options, such as stool-based testing,” Dr. Jacobson said.
| Table. Strong Recommendations of USMSTF For Optimizing Bowel Preparation Quality | |
| Recommendation | Quality of Evidence |
|---|---|
| We recommend that individuals undergoing colonoscopy receive verbal and written patient education instructions for all components of the colonoscopy preparation | High |
| We recommend limiting dietary modifications to the day before colonoscopy for ambulatory patients at low risk for inadequate bowel preparation | |
| We recommend dietary modifications should include the use of low-residue and low-fiber foods or full liquids for the early and midday meals on the day before colonoscopy when using a split-dose bowel preparation regimen for ambulatory patients at low risk for inadequate bowel preparation | |
| We do not recommend one bowel preparation purgative as superior to others about bowel preparation adequacy for ambulatory patients at low risk for inadequate bowel preparation | |
| We recommend against the use of hyperosmotic regimens in individuals at risk for volume overload or electrolyte disturbances | |
| We recommend a split-dose administration of bowel preparation purgatives for all patients, regardless of high-volume or low-volume preparation | |
| We recommend that a same-day regimen is an acceptable alternative to split dosing for individuals undergoing an afternoon colonoscopy | |
| We recommend the selection of a bowel preparation regimen that considers the individual’s medical history, medications, and, when available, the adequacy of bowel preparation reported from prior colonoscopies | Moderate |
| For individuals using a split-dose regimen for colonoscopy preparation, we recommend the consumption of the second portion begin 4-6 h before the time of colonoscopy and be completed at least 2 h before the procedure start | |
| We recommend bowel preparation quality be assessed only after all washing and suctioning have been completed, using reliably understood descriptors that communicate the adequacy of the preparation | |
| We recommend the term “adequate bowel preparation” be used to indicate that standard screening or surveillance intervals can be assigned based on the findings of the colonoscopy | |
| We recommend routine tracking of the rate of adequate bowel preparations at the level of individual endoscopists and at the level of the endoscopy unit | |
| We recommend an endoscopy unit-level and individual endoscopist-level bowel preparation adequacy rate of 90% | |
| When the bowel preparation is deemed inadequate to allow assigning standard screening or surveillance intervals, we recommend rescheduling a colonoscopy within 12 mo for screening or surveillance colonoscopies, and as soon as possible (i.e., generally within 3 mo) for those performed for an abnormal noncolonoscopic CRC screening test | |
| In the setting of a previous inadequate bowel preparation, we recommend modifications to bowel preparation instructions to include 1 or more of the following: increased attention to communicating the bowel preparation regimen instructions; increased use of patient navigation; restricting the intake of vegetables and legumes for 2 to 3 d before colonoscopy; allowing only clear liquids on the day before colonoscopy; the addition of promotility agents; treatment of underlying constipation; temporary cessation of anticholinergic, opioid, or other constipating medications; and/or the use of high-volume bowel preparation regimens | |
| We recommend individuals at high risk for inadequate bowel preparation quality be managed like individuals with a prior inadequate bowel preparation, with modifications to their bowel preparation regimen as previously described | |
| CRC, colorectal cancer; MSTF, Multisociety Task Force. Based on Am J Gastroenterol 2025;120[4]:738-764. | |
Patient Selection Is Key
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“So many of these recommendations are really trying to help improve patient adherence with colonoscopy,” said Derek Ebner, MD, a gastroenterologist at Mayo Clinic, in Rochester, Minn., who was not involved with the task force.
But Dr. Ebner expressed concerns that nonspecialists ordering colonoscopies may hear about new liberalized prep options and not select the right patients for them. “Colonoscopy is essentially an open-access procedure,” he said, adding that in many hospital systems the referring provider chooses the bowel prep regimen. “[Regarding] the primary care providers who are most often ordering these procedures, I think a fear would be if some of these risk factors aren’t recognized, and perhaps [patients are] getting prescribed a bowel prep that’s not going to be efficacious enough.”
—Jenny Blair
Dr. Ebner reported no relevant financial disclosures. Dr. Jacobson reported financial relationships with Curis and Guardant.
This article is from the June 2025 print issue.