Removal of suction trap valve leads to reduction in the extent to which colorectal polyps are fragmented upon retrieval

Introduction: Incomplete resection of adenomatous polyps removed by snare resection is an emerging issue relevant to interval colorectal cancer. A previous study (CARE trial) showed an incomplete resection rate in up to 23% of some colonoscopists' polypectomy specimens. A major limitation of determination of completeness of resection pathologically is polyp fragmentation. Once a polyp is fragmented into multiple pieces resection adequacy cannot be determined by the pathologist. The proposed study aims to assess if removal of the suction valve of the endoscope and covering the orifice with one's finger would decrease historical fragmentation rate of snared polyps. We hypothesized that removal of the suction cap might reduce shearing forces and thereby reduce polyp fragmentation. Methods: Patients undergoing screening, or surveillance colonoscopy at two hospitals from 3/2015 -11/2016 were included in the study. Polyps with sizes ranging from 5-10 mm removed by three separate endoscopists were included. The first 80 cases were removed by the usual method of pressing the suction valve (Cap On). The next consecutive 80 polyps were removed with suction valve removed, in which the polyp was suctioned into scope with finger covering the opening (Cap-Off). All polyps were removed with snare cautery or cold snare. Fragmentation was defined as multiple pieces in gross and microscopic description on pathology report. The rates of polyp fragmentation were also reported by Paris classification, histology and location. The rates of fragmentation were then compared in the Cap-On versus Cap- Off approach. Comparison between groups was by two sided Fisher's exact test with p=0.05 deemed significant. Olympus 190 series colonoscopies were used with polyp retrieved into Optimizer Polyp Trap (Conmed Endoscopic Technologies, Utica, NY). Results: When the standard Cap-On approach was used 71.3% of polyps were fragmented. In the subsequent Cap Off approach the rate was 36.3%, which was a significant reduction (p<0.001). All three endoscopists reduced their rate of fragmentation by 8.8%, 34.1%, 57.6% respectively. The reduction in fragmentation with Cap-Off approach in cauterized polyps was: Cap-On 75.6% vs. Cap-Off 28.2%, (p<0.001) and cold-snare polypectomy; Cap-On 66.7% versus Cap-Off 43.9%, (p=0.048). The most common Paris classification was 1S and reduction of fragmentation in these polyps was Cap-On 77.6% to Cap-Off 32.3%, (p<0.001). Conclusion: There is a notable decrease in fragmentation rates in 5-10 mm tubular adenomatous polyps using a retrieval approach in which the suction valve is removed. The extent to which this actually makes polypectomy resection interpretable requires dedicated pathology review. In order to further reduce fragmentation and improve interpretability, consideration should be made of approaches that bypass the suction valve entirely as well. (Table Presented).