Effect of Bowel Preparation Quality on Adenoma Detection Rate and Procedure Duration in Screening Colonoscopy

Purpose: Good quality bowel preparation is key for screening colonoscopy. Poor quality preparation can lead to missed lesions and prolong procedure time. Our aim was to study the impact of bowel preparation on adenoma detection rate and duration of the procedure. Methods: Retrospective analysis of average risk screening colonoscopies performed at a university hospital using the electronic reporting system was performed. All patients who underwent a colonoscopy with the indication “screening-average risk” during the study period [2006-2011] were included. Surveillance procedures and patients with high-risk family history were excluded since they are expected to have higher adenoma rate. We reviewed demographic details, procedural data and corresponding pathology reports. Polyp detection rate (PDR) is defined as the number of colonoscopies with at least one polyp removed/total number of procedures. Adenoma detection rate (ADR) is defined as the number of colonoscopies with removal of at least one pathologically confirmed adenoma/ total number of procedures. Bowel preparation was graded using Aronchick's scale (Table 1). Patients that had inadequate preparation were excluded from the analysis as they were rescheduled with re-preparation.Table: [1991] ResultsResults: Of 2,370 patients included in the study, 2291 (96.6%) had excellent/good/ fair bowel preparation, and 79 (3.3%) had poor bowel preparation. Cecal intubation rate and adenoma detection rate were similar in patients with excellent, good and fair preparation (see Table 2). But when poor preparation was compared with excellent preparation, ADR dropped to 18.9 % from 27.4% (p=0.06), and cecal intubation rate decreased to 70% from 93% (p=0.0001). Total duration of normal colonoscopies tended to increase progressively as the bowel preparation quality went down from excellent to poor.Table: Aronchick's scaleConclusion: Poor quality bowel preparation in screening colonoscopy leads to reduced cecal intubation rate, tends to increase procedure time, and reduce adenoma detection rate. Hence poor quality bowel preparation should be recognized early and lead to rescheduling the procedure rather than risking a poor quality screening colonoscopy.