An endoscopist-blinded, randomized, controlled trial of a simple visual aid to improve bowel preparation for screening colonoscopy

Gastrointest Endosc. 2011 Feb;73(2):307-14. doi: 10.1016/j.gie.2010.10.013. Epub 2010 Dec 18.


Background: The effect of patient education on bowel preparation for colonoscopy has not been well studied. An improvement in patient understanding of the rationale for bowel preparation before colonoscopy might enhance adherence to the prescribed bowel regimen and improve bowel preparation quality.

Objective: To measure the effect of a simple educational intervention on the quality of bowel preparation during colonoscopy.

Design: Prospective, single-center, endoscopist-blinded, randomized, controlled trial.

Setting: Tertiary-care center.

Patients: This study involved outpatients directly referred for screening colonoscopy.

Intervention: Inclusion of a visual aid depicting both clean and dirty colons in addition to standard written colonoscopy instructions.

Main outcome measurements: The primary outcome was the quality of the bowel preparation according to the Boston Bowel Preparation Scale (BBPS). Secondary outcomes included the need for repeat colonoscopy because of inadequate bowel preparation, insertion and withdrawal time, polyps detected, and patient tolerance of bowel preparation and colonoscopy.

Results: We analyzed 492 patients given a visual aid and 477 controls. The percentage of colonoscopies with a BBPS score≥5 was similar in both groups (91% visual aid vs 89% control, P=.43). The odds ratio for having a BBPS≥5 in the visual aid group was 1.24 (95% CI, 0.83-1.87) compared with controls. Other secondary outcomes were similar between groups.

Limitations: Single-center study.

Conclusion: A simple card with photographs and text explaining the rationale for bowel preparation did not change the quality of bowel preparation in patients directly referred for screening colonoscopy. Future educational studies may need to include more interactive or intensive methods. (

Clinical trial registration number: NCT00643682.).

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Administration, Oral
  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Cathartics / administration & dosage*
  • Colonic Diseases / diagnosis*
  • Colonoscopy / methods*
  • Female
  • Humans
  • Male
  • Mass Screening / methods*
  • Middle Aged
  • Prospective Studies
  • Reproducibility of Results
  • Single-Blind Method
  • Young Adult


  • Cathartics

Associated data