Background: Flat and sessile lesions are being identified more frequently because of increased awareness, improved endoscopic skills, and enhanced imaging. The defiant polyp (DP) is a lesion identified at colonoscopy that defies resection by the standard snare polypectomy technique. Increasingly, the DP undergoes photodocumentation and tissue sampling, and the patient is referred for an attempt at curative colonoscopic resection. Objective: To evaluate the current nature of the DPs and outcomes of their endoscopic resection. Design: Retrospective study. Setting: Tertiary referral center. Patients and Interventions: Patients with colorectal polyps not amenable to standard snare polypectomy were referred to a single endoscopist at a tertiary center for an attempt at curative endoscopic resection. The indication DP was applied prospectively, as defined previously, beginning in June 2007. An electronic endoscopy report database was searched for this indication from June 2007 to October 2009 for a single endoscopist at an endoscopy referral center. Data pertaining to patient age and sex, polyp site and histopathology, resection technique, use of adjunctive ablation, adverse events, and residual/recurrent neoplasia at follow-up were culled. Submucosal injection of varying quantities of normal saline solution tinted with methylene blue dye was used for endoscopic resection. Standard and mini-snares were used with pure coagulation current. Main Outcome Measurements: Complete resection, complications, recurrence. Results: This study included 274 patients (50.4% women, age 65 [standard deviation 12] years) with a total of 315 DPs who were referred for attempted endoscopic resection. The majority of DPs were located in the right side of the colon (226; 72%). The mean size was estimated at 23 mm (range 8-100 mm; standard deviation 13). In 29 DPs (10%), surgery was required because endoscopic resection was deemed unsuitable because of the unfavorable appearance (n = 3), the location (n = 9), or the inability to lift (n = 10) or because of submucosal invasion on post-EMR histopathology (n = 7). Complete endoscopic eradication (R0) was achieved in a single session in 286 DPs (91%). En bloc resection was performed in 153 polyps (53.5%) and piecemeal resection in 132 (46%). Histopathology revealed 178 tubular adenomas (56.5%), 62 serrated adenomas (20%), 27 tubulovillous adenomas (9%), 10 hyperplastic polyps (3%), and 14 adenocarcinomas (4.5%). Adjunctive ablation of focal residual neoplastic tissue was applied in 69 DPs (24%) to achieve R0. Procedure-related adverse events were recorded in 29 of 249 patients (11.6%). Acute bleeding occurred in 9 patients (1 required hospitalization and repeat endoscopy). There was 1 microperforation managed with clip closure and antibiotics. Delayed bleeding (1-6 days post-procedure) was observed in 18 patients (7.2%), of whom 8 required hospitalization and 4 colonoscopy for hemostasis. Among the patients who underwent follow-up surveillance colonoscopy (135 of 258 patients), residual/recurrent neoplastic tissue at the site of the previous EMR was identified in 36 (27%). Residual/recurrent neoplasia was successfully eradicated with further endoscopic resection or ablation. Limitations: A retrospective design. Conclusions: DPs consist predominantly of sessile and flat adenomas including serrated adenomas. Most DPs can be successfully eradicated at dedicated therapeutic colonoscopy by using adjunctive resection and ablation techniques. The R0 rate is high and the adverse event rate is low. A relatively high rate of local residual/recurrent neoplasia at the resection site underscores the importance of follow-up colonoscopy. (Gastrointest Endosc 2012;76:255-63.)
