Optimal Bowel Preparation for Colonoscopy

Dietary Recommendations

The American Gastroenterological Association recommends limiting dietary modifications to the day before colonoscopy for patients at low risk for inadequate bowel preparation 2, 3
Patients should follow a low-residue/low-fiber diet for early and midday meals on the day before colonoscopy, as recommended by the American Gastroenterological Association 2, 1
A low-residue diet should be avoided with high-fiber foods such as cereals, beans, peas, nuts, seeds, and raw or dried fruits and vegetables on the day before colonoscopy, according to the American Gastroenterological Association 1
The American Gastroenterological Association suggests switching to clear liquids for the evening meal and continuing until the procedure 1
Additional days of dietary restrictions beyond one day before colonoscopy confer no benefit in bowel preparation adequacy, as stated by the American Gastroenterological Association 1

The American Gastroenterological Association strongly recommends a split-dose administration of bowel preparation purgatives for all patients, regardless of high-volume or low-volume preparation 2, 4
For split-dose regimens, the second portion should begin 4-6 hours before colonoscopy and be completed at least 2 hours before the procedure, as recommended by the American Gastroenterological Association 2, 3, 5
The American Gastroenterological Association suggests that same-day regimen is an acceptable alternative to split dosing for afternoon colonoscopies 2, 3, 5
No specific bowel preparation purgative is superior to others for patients at low risk for inadequate preparation, according to the American Gastroenterological Association 2, 3
The American Gastroenterological Association recommends 2L bowel preparation regimens over 4L regimens when possible 2, 3

For patients at high risk for inadequate bowel preparation, the American Gastroenterological Association recommends considering a more restrictive approach: clear liquids only on the day before colonoscopy 6, 7
For high-risk patients, a suggested regimen includes split-dose 4L polyethylene glycol-electrolyte lavage solution plus 15mg bisacodyl the afternoon before colonoscopy, with a low-residue diet 3 and 2 days before colonoscopy, changing to clear liquids the day before, as recommended by the American Gastroenterological Association 7
The American Gastroenterological Association suggests discontinuing iron supplements at least 7 days before colonoscopy to prevent dark, sticky stool that can obscure detection of polyps 1

Unnecessarily restricting diet for more than one day before colonoscopy can reduce compliance without improving outcomes, as stated by the American Gastroenterological Association 1
Failing to provide both verbal and written patient education instructions for colonoscopy preparation, according to the American Gastroenterological Association 6, 7
Not following split-dose regimen, which is superior to single-dose administration, as recommended by the American Gastroenterological Association 4
Consuming solid foods less than 6 hours before the procedure increases aspiration risk, according to the American Gastroenterological Association 5
Failing to complete the bowel preparation at least 2 hours before the procedure, as stated by the American Gastroenterological Association 2, 3