Bowel preparation for colonoscopy: current strategies. A narrative review

Objective. To summarize current evidence on the principles of bowel preparation for colonoscopy. Key points. The quality of bowel cleansing is an independent quality indicator of colonoscopy and affects mucosal visualization, detection of colorectal neoplasia, and the need for repeat examination. Current international guidelines consider split-dose regimens preferable for elective colonoscopy, whereas a same-day morning regimen is mainly acceptable for procedures scheduled in the afternoon. The last dose of the bowel-cleansing agent should preferably be started within 5 hours before colonoscopy and completed at least 2 hours before the procedure. Selection of the bowel preparation should take into account age, chronic constipation, diabetes mellitus, chronic kidney disease, cardiovascular comorbidity, concomitant medications, and the risk of fluid and electrolyte disturbances. Iso-osmotic polyethylene glycol solutions with electrolytes, together with low-volume polyethylene glycol preparations containing ascorbate, remain important first-line options because of their established efficacy and predictable safety profile. The macrogol 4000 and electrolyte preparation Lavacol is registered both for bowel cleansing and for the symptomatic treatment of constipation, which may be of practical relevance in patients prone to constipation. Low-volume sulfate-based preparations provide effective bowel cleansing but require adequate additional hydration and should be used cautiously in older and comorbid patients because of the risk of fluid and electrolyte disturbances. Conclusion. Optimal bowel preparation for colonoscopy should be individualized and include assessment of risk factors, appropriate dietary modification, preferential use of a split-dose regimen, and selection of the preparation according to the patient’s clinical profile. Standardization of these measures may improve the rate of adequate bowel cleansing and the diagnostic yield of colonoscopy.