Mo1385 Diagnostic and Therapeutic Impacts of Elective Colonoscopy Following Acute Sigmoid Diverticulitis Abdullah Alatawi, Karine Pautrat, Philippe Soyer, Violaine Ozenne, Ulriikka Chaput, Rea Lo Dico, Christelle Duteil, Patrice D. Valleur, Philippe R. Marteau, Xavier Dray* Digestive Diseases, APHP, Lariboisiere Hospital, & Denis Diderot, Paris 7 University, Paris, France; Abdominal Imaging, APHP, Lariboisiere Hospital, & Denis Diderot, Paris 7 University, Paris, France; Epidemiology, APHP, Lariboisiere Hospital, Paris, France Introduction: The diagnosis of acute sigmoid diverticulitis (ASD) is mainly based on clinical, biological and CT-scan findings. Elective colonoscopy is sometimes proposed after medical treatment, to rule out differential diagnosis and to detect associated conditions (such as advanced adenomas and cancer) before surveillance or elective surgery is considered. Aims and Methods: In this 6-year, monocentric, retrospective study, we aimed to evaluate the diagnostic and therapeutic impact of elective colonoscopy in patients with recent onset of ASD. Clinical, radiological, and endoscopic data from patients who had an elective colonoscopy after medical treatment admitted for ASD were reviewed. Endpoints were (i) overall adenoma detection rate (ADR), (ii) advanced adenoma detection rate ( 10mm diameter, villous lesions 25%, high-grade dysplasia), (iii) therapeutic impact (as defined by changes in the surgical strategy, based on endoscopic findings). Results: From January 2005 to January 2011, 252 patients admitted in our institution for ASD. Among them, 121 (48%, 67 women, mean age 62 year) had an elective colonoscopy after conservative treatment of ASD. Past medical history included previous colonoscopy (25 patients, 20.8%), previous onset of ASD (27 patients, 22.4%), familial history of digestive cancer (7 patients, 5,5%). CT-scan displayed patterns of tumor-like lesions of the sigmoid in 7 patients (5.5%), sigmoid stenosis in 10 patients (8.3%), peri-sigmoidal abscess in 21 patients (18%). Elective colonoscopy was performed in a mean time of 62 days after admission for ASD. Colonoscopy was not completed in 8 patients, because of sigmoid stenosis in 7 cases. In one patient with incomplete colonoscopy, a tumor upstream the sigmoid stenosis was suspected on the initial CT-scan, and adenocarcinoma was confirmed during elective surgery (and therefore not credited as a therapeutic change based on colonoscopy). Colonoscopy was total in 113 (93.3%) patients. No endoscopic complication was observed. Adenoma, advanced adenoma, and adenocarcinoma detection rates were 13.2%, 1.6% and 0.8%, respectively. The therapeutic impact of colonoscopy was 0.8%. Conclusion: Elective colonoscopy following medical treatment of ASD has low diagnostic rates for adenomas, for advanced adenomas and for colorectal cancer, and therefore rarely modifies the therapeutic strategy. It should be proposed after ASD only in highly selected patients, those presenting with reasonable doubt on initial CT-scan, and those with identified risk factors for advanced adenomas and adenocarcinoma of the colon.