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People who are given extra information about preparing for their colonoscopy are likely to have clearer bowels before the procedure, meaning it is more likely to be successful. About a quarter of people currently having colonoscopy are poorly prepared and this prevents a good view of the whole bowel. Better preparation allows more accurate diagnoses, shorter procedures and fewer repeat procedures. This could lower costs.

The seven trials included in this evidence review all used different patient education interventions. These included illustrated printed materials, videos, group education sessions and telephone reminders. While six of the seven studies showed an improvement in bowel preparation, there is not enough evidence to show that one method worked better than any other.

Three of the included trials were carried out in the US, and four in Asia. Similar preparations for colonoscopy are used in the UK, and given the large number of colonoscopies carried out, for screening, diagnosis and monitoring simple ways to improve detection of abnormalities are welcome.

Why was this study needed?

Colonoscopy inspects the whole of the large bowel with a flexible tube and camera. It is a useful test for identifying growths and for taking biopsy samples of abnormal looking areas of the bowel lining.

Preparation involves drinking only clear liquids the day before and taking laxatives. This can be off-putting for patients. Bowel contents obscure the view and this means that the procedure takes longer or has to be repeated on another day. Polyps (growths) may also be missed.

Around 150 colonoscopies are performed per 10,000 people in England every year, each costing the NHS about £532. An estimated 17% to 33% of procedures are not adequately prepared. Good patient information is needed to ensure patients follow colonoscopy preparation instructions properly. This review tried to find out what type of information works best.

What did this study do?

This systematic review looked for randomised trials or quasi-randomised trials that investigated how well patient education interventions worked to improve bowel preparation before colonoscopy. Researchers found seven suitable trials including 2,660 adults.

The trials were too different from each other to allow pooling of their results. They used three different scales to assess bowel preparation success. The definition of “usual care” also varied but all included written instructions in some form.

The interventions tested were all different: three trials used printed materials (a cartoon visual aid and illustrated brochures), two tested videos (one online and one in a group setting), one looked at telephone calls made by doctors the day before the colonoscopy, and one looked at a face-to-face group intervention. The endoscopist in the trials was unaware of the group that each patient had been allocated to and trials were scored at a low or moderate risk of bias.

What did it find?

  • Six out of the seven included trials showed that the patient education intervention tested improved the quality of bowel preparation.
  • One study of 218 people used the Aronchick scale, which uses the terms inadequate, poor, fair, good and excellent for bowel preparation. Eighty one per cent of bowel preparations in the intervention group were rated as “good” or “excellent”, compared to 48% in the usual care group (p<0.001). This intervention was a group video, followed by a question and answer session with a doctor.
  • Three studies used the Ottawa Bowel Preparation Scale, which gives a score from 0 to 14, with 14 being the worst preparation. All three showed a lower score in the intervention groups. In one trial about 10% of people had better preparation (a score less than 6) 82% in the intervention group compared to 70% in the control group (p=0.001). Interventions included a phone call the day before the procedure to remind people about how to prepare; a short online video, and an educational booklet.
  • A group education session led by a doctor and a cartoon visual aid also led to about 10% improvement in the numbers with satisfactory scores. One unsuccessful intervention was a visual aid with pictures.

What does current guidance say on this issue?

There is no UK-wide guidance on bowel preparation for colonoscopy, or advice on informing patients about how to prepare properly. Guidance published in 2015 from the American Society for Gastrointestinal Endoscopy and guidance published in 2013 from the European Society of Gastrointestinal Endoscopy both recommend that instructions for bowel preparation should be given verbally, as well as written down.

An online search shows that many UK hospitals produce their own written instructions for colonoscopy preparation, which vary somewhat from hospital to hospital.

What are the implications?

This review found that, compared to usual care, patient education interventions improve the quality of bowel preparation. This could cut costs by reducing the number of procedures that have to be repeated.

The lack of national guidance means practice across the UK varies. The review could not draw any conclusions about which patient education interventions are most effective, but it appears that detailed instructions can improve preparation. Hospitals could consider which interventions, including face-to-face, video and printed materials, are feasible for them.

The authors suggest that hospitals review the effectiveness of their existing procedures, then test any changes made in a standardised way.


Citation and Funding

Kurlander JE, Sondhi AR, Waljee A, et al. How Efficacious Are Patient Education Interventions to Improve Bowel Preparation for Colonoscopy? A Systematic Review. PLoS One. 2016;11(10):e0164442

Waljee A’s research is funded by a VA HSR&D CDA-2 Career Development Award 1IK2HX000775.



Hendry P, Jenkins J, Diament R. The impact of poor bowel preparation on colonoscopy: a prospective single centre study of 10 571 colonoscopies. Colorectal Dis. 2007;9(8):745-8.

Hassan C, Bretthauer M, Kaminski MF, et al. Bowel preparation for colonoscopy: European Society of Gastrointestinal Endoscopy (ESGE) Guideline. Endoscopy. 2013;45(2):142-50.

National tariff payment system 2014/15. Monitor / NHS England; 2013.

NICE. Colorectal cancer: diagnosis and management. CG131. London: National Institute for Health and Care Excellence; 2011.

Right care. Map 9A: Rate of colonoscopy procedures and flexisigmoidoscopy procedures per population by PCT. Indirectly standardised rate, adjusted for age, sex and deprivation 2012/13. In: NHS atlas of variation. Right care; 2015:58-60.

Saltzman JR, Cash BD, Pasha SF, et al. Bowel preparation before colonoscopy. Gastrointest Endosc. 2015;81(4):781.

Produced by the University of Southampton and Bazian on behalf of NIHR through the NIHR Dissemination Centre


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Colonoscopy is a procedure where a flexible tube containing a light source and a channel for viewing and one for biopsy. This is inserted through the rectum into the colon. Tissue samples (biopsies) of any abnormal areas can be taken during this procedure, and growths can be removed. 
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