Optimizing Bowel Preparation in High-risk Patients Undergoing Colonoscopy: A Narrative Review

Identifying patients at high risk for poor bowel preparation preceding a colonoscopy is critical to successful colorectal cancer screening. High-risk patients, such as those who are obese, diabetic, opioid users, or former smokers, often have comorbidity, medication, and sociodemographic factors that lead to suboptimal bowel preparation even when following protocol. Suboptimal preparation results in missed lesions, longer procedure times, and increased healthcare costs. Optimal visualization of the colon mucosa is achieved through effective bowel preparation. Polyethylene glycol (PEG) solutions are preferred for their safety, especially in patients with kidney or cardiac disease. Split-dose PEG regimens with a low-residue diet are recommended by the American Gastroenterological Association to promote cleansing and patient tolerance. Tailored regimens can be employed in high-risk patients, including those with chronic constipation, opioid dependence, or diabetes. Educational interventions, such as written and verbal instructions, patient navigators, and mobile device reminders, improve compliance. Medical strategies include split-dose PEG-electrolyte lavage solution with bisacodyl, additional purgatives for select patients, and avoidance of sodium phosphate in elderly or renally impaired individuals. Open-access colonoscopy services have expanded following the COVID-19 pandemic to manage backlogs and improve access. Improving education, simplifying regimens, and targeting interventions can reduce repeat procedures and enhance colorectal cancer detection. This narrative review summarizes patient-, medication-, and system-level risk factors for inadequate bowel preparation in high-risk populations and synthesizes practical, evidence-based strategies to optimize colonoscopy quality, including in open-access settings.