Optimizing bowel preparation for colonoscopy: Updated consensus recommendations

WHO WROTE THE GUIDELINES?

The US Multi-Society Task Force on Colorectal Cancer updated the 2014 consensus recommendations⁴ and published their work in 2025.³ The Task Force represents each of the 3 gastroenterological societies: the American College of Gastroenterology, American Gastroenterological Association, and American Society for Gastrointestinal Endoscopy. The 2025 consensus provides updated evidence-based recommendations for outpatients undergoing colonoscopies at low risk for inadequate bowel preparation.³ A literature review was led by the primary author, who developed statements with evidence tables to be reviewed by the entire committee. The strength of the statement was assessed based on the quality of evidence.

WHAT ARE THE MAIN RECOMMENDATIONS?

Inadequate preparation management

Modify bowel preparation instructions for patients with a history of inadequate preparation or at risk for it as follows: split-dose 4 L polyethylene glycol (PEG) and electrolyte lavage solution, bisacodyl 15 mg the afternoon before the colonoscopy, and a more restrictive diet (low-residue diet days 3 and 2 before colonoscopy and clear liquids day 1 before; Figure 1³).¹³ In a randomized trial of 256 patients with previous inadequate cleansing, all participants received a 3-day low-residue diet and bisacodyl 10 mg the day before colonoscopy, combined with either split-dose 4 L PEG or split-dose 2 L PEG plus ascorbic acid. The 4-L PEG regimen achieved significantly higher adequate preparation rates than the 2-L regimen (81.1% vs 67.4%, odds ratio 2.07, 95% confidence interval 1.16–3.69).^4,13

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Figure 1

Bowel preparation dietary protocol.

Based on information from reference 3.

Repeat colonoscopy within 12 months.¹⁴

WHAT IS DIFFERENT FROM PREVIOUS GUIDELINES?

DO OTHER SOCIETIES AGREE OR DISAGREE?

The European Society of Gastrointestinal Endoscopy guideline¹⁵ generally aligns with US Multi-Society Task Force recommendations³ on split dosing and dietary simplification.

International consensus on the fundamentals—split dosing, minimizing dietary burden, and individualized preparation—is strong, though implementation details and quality monitoring standards differ across healthcare systems.

HOW WILL THIS CHANGE DAILY PRACTICE?

The 2025 US Multi-Society Task Force recommendations are poised to reshape how endoscopy practices approach bowel preparation, with implications far beyond simple protocol adjustments. The shift toward patient-centered regimens—particularly the allowance of solid low-residue foods the day before—will enhance patient experience by reducing hunger, nausea, and anxiety, thereby improving willingness to undergo repeat procedures. At the same time, dietary simplification requires comprehensive revision of patient education materials and staff training. Many practices have long relied on complex, multi-day restriction sheets; transitioning to streamlined low-residue instructions will require retraining of nursing staff and confidence-building among clinicians accustomed to clear-liquid protocols.

Operationally, several changes present significant challenges. Universal adoption of split-dose regimens means offices must deliver clear guidance on morning dosing, even if this requires patients to wake at 3 AM to 4 AM for early morning procedures. This practical hurdle underscores the need for enhanced patient education and may prompt some centers to reconsider scheduling patterns. Likewise, the Task Force’s preference for 2-L preparations is likely to accelerate adoption of lower-volume regimens, improving tolerability but necessitating adjustments in procurement, prescribing habits, and insurance coverage.

Perhaps the most transformative change is the mandate to track preparation adequacy at both the unit and individual endoscopist level, with a benchmark of 90%. Most practices currently lack systems for such granular monitoring, so implementation will require new data collection processes, regular reporting, and targeted quality improvement initiatives. The strong endorsement of patient navigation—via apps, automated reminders, or dedicated staff—offers a proven strategy to raise adequacy rates, yet requires meaningful investment of time and resources. For smaller practices, collaboration or shared technology solutions may be necessary to meet these expectations cost-effectively.

An important practical consideration in open-access systems is clarifying responsibility for bowel preparation instructions. In many healthcare systems, primary care clinicians order colonoscopies while endoscopy units provide preparation instructions. Some gastroenterology practices and institutions allow for a low-residue diet, while others do not. To avoid confusing patients, it is important to clarify the instructions patients will receive, including instructions provided on the institution’s or practice’s website and through a patient portal or mail.

WHEN WOULD THE GUIDELINES NOT APPLY?

The US Multi-Society Task Force acknowledges important limitations in applying these recommendations, particularly for complex patient populations, patients at risk for an inadequate preparation, and challenging clinical scenarios. Risk factors for inadequate bowel preparation quality include cirrhosis, Parkinson disease, tricyclic antidepressant use, diabetes, opiate use, gastroparesis, previous colorectal surgery, constipation, tobacco use, and age over 65; while not true of all risk factors, many impact intestinal motility.^16,17 Understanding these exceptions is crucial for safe and effective implementation.

Hospitalized patients represent a significant population where standard outpatient protocols may not apply. Inpatients often have multiple comorbidities, delayed procedure scheduling, medication interactions, and limited mobility that complicate preparation regimens. The timing requirements for split dosing become particularly challenging when procedures are scheduled urgently or when patients cannot reliably self-administer preparations. These patients may require individualized approaches with nursing supervision and modified timing protocols.

Patients with severe renal insufficiency or heart failure cannot safely use hyperosmotic preparations.¹⁸ Similarly, patients with significant gastrointestinal disorders such as severe gastroparesis, inflammatory bowel disease with strictures, or previous extensive colorectal surgery may need specialized approaches based on their altered anatomy and physiology.

Neurologically impaired patients, including those with dementia, Parkinson disease, or developmental disabilities, may be unable to comply with standard preparation instructions. These patients often require caregiver assistance, modified regimens, and sometimes inpatient preparation protocols that fall outside the scope of these outpatient-focused recommendations.¹⁹

Pregnancy presents unique challenges where both preparation agents and procedure timing must be carefully considered. The guidelines do not address obstetric considerations, and these patients require individualized management in consultation with obstetric clinicians.²⁰

Cultural and language barriers may limit the applicability of standard education and navigation approaches. Patients with limited English proficiency, cultural dietary restrictions, or health literacy challenges may need enhanced support beyond what these guidelines specifically address. Practices serving diverse populations must develop culturally appropriate adaptations while maintaining preparation effectiveness.²¹

Emergency or urgent procedures often cannot accommodate the ideal timing recommendations, particularly for split-dose regimens. In these situations, clinicians must balance preparation quality against clinical urgency, often accepting suboptimal preparation in favor of timely diagnosis or treatment.

Resource-limited settings may lack access to patient navigation systems or low-volume preparations. Rural practices or those in underserved areas may need to adapt recommendations based on available resources while striving to achieve optimal preparation quality within existing constraints.

DISCLOSURES

Dr. Beveridge has disclosed teaching and speaking for Asofarma, GastroGirl, and Vindico, and consulting for Sanofi, Takeda Pharmaceuticals, and Christopher Place Healthcare. Dr. Kawas reported no relevant financial relationships which, in the context of their contributions, could be perceived as a potential conflict of interest.