BACKGROUND: For patients requiring colonoscopy while admitted to hospital, achieving adequate cleansing of the colon is often difficult.OBJECTIVES: To assess the impact of patient education, in the form of both counselling and written instructions, on bowel cleanliness at colonoscopy.METHODS: A total of 38 inpatients at a tertiary care hospital in Vancouver, British Columbia, who were referred to the gastroenterology service for colonoscopy were enrolled in the present study. Sixteen patients were randomly assigned to the intervention group, while 22 patients comprised the control group. Both groups received a clear liquid diet and 4 L of a commercially available bowel preparation. The intervention group also received a brief counselling session and written instructions outlining the methods and rationale for bowel preparation before colonoscopy. Bowel cleanliness was assessed by the endoscopist using a five-point rating scale.RESULTS: The two groups were similar with respect to demographics, the indication for colonoscopy and findings at colonoscopy. The median bowel cleanliness scores in the control group and the enhanced-instruction group were 3.0 and 2.0, respectively (P=0.001).CONCLUSION: Patient counselling and written instructions are inexpensive, safe and simple interventions. Such interventions are an effective means of optimizing colonoscopy preparation in the inpatient setting.