# Bowel preparation for colonoscopy

Source: https://onco.cc/protocols/bowel-preparation-for-colonoscopy/  
OnCo record `bowel-preparation-for-colonoscopy` (Protocol). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

A colonoscopy can only find polyps and early cancers if the bowel is clean. Eat low-fibre food the day before, drink the laxative in two halves (the evening before and the morning of the test, or all on the day for an afternoon test), and finish the last dose at least two hours before the test. Follow your unit's written instructions, which come first.

## Summary

ESGE 2019 (GRADE): a low-fibre diet on the day before (strong, moderate); enhanced instructions, verbal or written, for patients and for ward staff caring for inpatients (strong, moderate); split-dose preparation for elective colonoscopy (strong, high), with same-day dosing an acceptable alternative for afternoon lists (strong, high); start the last dose within 5 hours of the procedure and finish it at least 2 hours before (strong, moderate); high- or low-volume PEG or clinically validated non-PEG agents, individualised where fluid and electrolyte disturbance is a risk (strong, moderate); simethicone suggested (weak, moderate); no routine enemas (strong, moderate), no routine oral sodium phosphate (strong, low) and no routine prokinetics (weak, low). After an inadequate preparation, repeat within a year (strong, moderate). PEG in inflammatory bowel disease and urgent bleeding; insufficient evidence in pregnancy. The US Multi-Society Task Force (2025) agrees on split dosing (and suggests 2 litres may be enough), same-day dosing for afternoon procedures (an inferior alternative in the morning), restriction limited to the day before with clear liquids or low-fibre food for early meals, and simethicone, and sets a target of more than 90% adequate preparations per endoscopist and per unit; ESGE's quality committee sets a minimum standard of 90% or more, assessed on validated scales.

## Fields

- Kind: Protocol
- Last checked: 2026-11-11
- Also known as: bowel prep; colonoscopy prep; split-dose bowel preparation; laxative before colonoscopy; PEG bowel prep; Moviprep; low-fibre diet before colonoscopy; clear liquid diet before colonoscopy

## Connected records

- cancers: [Colorectal cancer](https://onco.cc/cancers/colorectal/)
- terms: [Colonoscopy](https://onco.cc/terms/colonoscopy/)

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