The impact of poor bowel preparation on colonoscopy: a prospective single centre study of 10 571 colonoscopies

Objective Colonoscopy is regarded as the most sensitive method of evaluating the colon. Inadequate preparation reduces sensitivity and has adverse implications for individual patients and the Heath Service. Method Data concerning the adequacy of bowel preparation and colonoscopy completion rates were prospectively collected on all colonoscopies performed in a single centre between January 1996 and January 2005. In addition, the strategy of further investigation in the event of incomplete examination was assessed. Results A total of 10 571 colonoscopies were assessed and poor bowel preparation was identified in 1788 of these cases (16.9%). The completion rate was 67.5% in those with satisfactory preparation. In patients with poor preparation, 36% of colonoscopies were complete. Incomplete examination was more likely with poor preparation [OR = 3.76 (95% CI, 3.38–4.18), P = 0.0005]. Poor preparation was more likely for inpatients [OR = 3.54 (95% CI 3.14–3.96), P = 0.0005]. Even with satisfactory preparation, inpatient completion rates were significantly less [OR = 1.78 (95% CI, 3.14–3.96), P = 0.0005). A further 542 diagnostic procedures were undertaken in the poor preparation group, an additional £101 950 (€149 459) in expenditure. Conclusion This study supports the view that inpatients fare badly. This is partly explained by higher rates of poor preparation; however, completion rates were reduced even with adequate preparation. Failed investigation and prolonged hospital stay increase cost. Colonoscopy completion rates need to be improved with particular attention to inpatients.