What is the recommended colon preparation regimen for a colonoscopy?

Recommended Colon Preparation Regimen for Colonoscopy

For optimal colonoscopy outcomes, a split-dose bowel preparation regimen is strongly recommended for all patients, regardless of whether high-volume or low-volume preparation is used. 1

General Preparation Recommendations

• 2-liter bowel preparation regimens are suggested over 4-liter regimens due to better patient tolerance while maintaining adequate cleansing 1
• Selection of bowel preparation should consider the individual's medical history, medications, and prior colonoscopy preparation adequacy 1
• Hyperosmotic regimens should be avoided in individuals at risk for volume overload or electrolyte disturbances 1
• Oral simethicone can be used as an adjunctive agent for bowel preparation 1

Timing of Preparation

Split-Dose Regimen (Preferred Approach)

• For all colonoscopies, split-dose administration is strongly recommended 1
• The second portion should begin 4-6 hours before colonoscopy and be completed at least 2 hours before the procedure 1
• This timing is critical as each additional hour between the last purgative ingestion and colonoscopy can decrease the likelihood of good preparation by up to 10% 1

Same-Day Regimen (Alternative Approach)

• For afternoon colonoscopies: Same-day regimen is an acceptable alternative to split dosing 1
• For morning colonoscopies: Same-day regimen is an inferior alternative to split dosing 1
• Same-day regimens may offer better sleep quality but might cause more side effects like nausea 1

Dietary Recommendations

• Follow a low-residue/low-fiber diet for early and midday meals on the day before colonoscopy 2
• Avoid high-fiber foods such as cereals, beans, peas, nuts, seeds, and raw or dried fruits and vegetables on the day before colonoscopy 2
• Switch to clear liquids for the evening meal the day before colonoscopy 2
• Discontinue iron supplements at least 7 days before colonoscopy to prevent dark, sticky stool that can obscure detection of polyps 2

Patient Education and Navigation

• Both verbal and written patient education instructions should be provided for all components of the colonoscopy preparation 1
• Some form of patient navigation, including telephonic or virtual navigation using automated electronic messaging, is suggested to improve rates of adequate bowel preparation 1

Special Considerations

• For patients with previous inadequate bowel preparation, modifications should include: 1
  • Increased attention to communicating preparation instructions
  • Restricting intake of vegetables and legumes for 2-3 days before colonoscopy
  • Allowing only clear liquids on the day before colonoscopy
  • Adding promotility agents
  • Treating underlying constipation
  • Temporarily stopping anticholinergic, opioid, or other constipating medications
  • Using high-volume bowel preparation regimens

Quality Assessment

• Bowel preparation quality should be assessed only after all washing and suctioning have been completed 1
• The term "adequate bowel preparation" indicates that standard screening or surveillance intervals can be assigned based on colonoscopy findings 1
• Endoscopy units should track bowel preparation adequacy rates, with a target of 90% at both individual endoscopist and unit levels 1

Management of Inadequate Preparation

• When bowel preparation is inadequate, colonoscopy should be rescheduled within 12 months for screening or surveillance colonoscopies 1
• For colonoscopies performed due to abnormal non-colonoscopic colorectal cancer screening tests, rescheduling should occur as soon as possible (generally within 3 months) 1
• Same-day salvage maneuvers can be used when feasible for inadequate bowel preparations 1