Combined Cap-Assisted Total Water With Chromoendoscopy Further Enhance Proximal Adenoma Detection (ADR) and Hyperplastic Polyp Detection: A Retrospective Analysis

Abstract

Introduction: Missed lesions in proximal colon contribute to interval cancers. Water exchange (WE) combined with chromoendoscopy increased ADR (JIG2012;3:114). Cap-assisted WE further increased ADR (GIE2013;77:944). Combined use of cap-assisted total water colonoscopy, eliminating air, further increased proximal ADR in screening cases. We hypothesize that combined cap-assisted total water with chromoendoscopy on scope withdrawal can further improve proximal ADR in surveillance colonoscopy.Table: Table. Patients demographics, volume of water used, cecal intubation and bowel preparation scoreTable: Table. Adenomas and hyperplastic polyps detection in proximal colonMethods: Retrospective analysis of 3 consecutive series of patients examined with cap-assisted water exchange (CAWE), cap-assisted total water (CATW) and combined cap-assisted total water and chromoendoscopy (CATWC) (with 0.002% indigocarmine/water). CAWE was performed with air turned off and water was infused to facilitate scope insertion while dirty water was suctioned on insertion and withdrawal. Air was used on withdrawal to facilitate examination/removal of lesions. Insertion method was same as CAWE for CATW and CATWC. In CATW, plain water was used and exchanged, with air pockets suctioned to facilitate examination. In CATWC, indigocarmine solution was infused upon withdrawal from cecum and dirty water was exchanged. In both groups, no air was used for entire examination, and polypectomy was done underwater. Small (<5 mm) polyps were removed with biopsy forceps; 5-8 mm polyps, cold snare; and >8 mm polyps, hot snare. Results: 105 patients (35 per group) were included. Patients' demographics were comparable, with no difference in mean interval between index screening and surveillance colonoscopy (4; 4.12; 4.14 years respectively). Total amount of water infused and suctioned were comparable between CATW and CATWC but significantly more than CAWE, and so was the withdrawal time. The overall and proximal ADRs (< 5mm) were higher for CATWC compared with CATW and CAWE (P<0.05). The proximal hyperplastic polyp detection rate was significantly higher for CATWC when compared to CATW and CAWE (40% vs.14.3% vs.14.3% respectively, P<0.05). Conclusion: Limitations: retrospective analysis of consecutive series with small number of patients. Combined cap-assisted total water and chromoendoscopy (CATWC) further improved proximal ADR especially <5mm adenomas. It significantly increased detection of proximal hyperplastic polyps (closely related to sessile serrated polyps) (CGH2013;11:760) in surveillance colonoscopy. These intriguing preliminary data deserves to be confirmed in a prospective RCT.