491 Retrograde Single-Balloon Enteroscopy: a Single-Center Experience of 107 Patients Kaci E. Christian*, Karan Kapoor, Eric M. Goldberg University of Maryland Medical Center, Baltimore, MD Background: Single-balloon enteroscopy (SBE) represents a novel approach to diagnose and treat small bowel disease. The small bowel can be deeply intubated via the anterograde (mouth) or retrograde (anus) approach depending on the probable location of the suspected lesion. Single balloon enteroscopy has different performance characteristics depending upon the route chosen, but most studies combine the information. This study constitutes the largest published cohort to date of retrograde single-balloon enteroscopy (RSBE). Objectives: To evaluate the technical success, diagnostic yield and therapeutic potential of RSBE. Design: Single tertiarycare referral center, retrospective study. Setting: University of Maryland Medical Center, Baltimore, MD. Patients: A total of 105 patients were referred for RSBE between July 2007 and September 2013. Results: A total of 107 procedures were performed. The mean age of patients was 57 years, 51.4% were female and 79.4% of procedures were performed on an outpatient basis. Indications included gastrointestinal bleeding, suspected or confirmed inflammatory bowel disease (IBD), imaging suggestive of pathology other than bleeding or IBD and other. Pre-procedural imaging was performed in 67.3% of patients with a 33.3% concordance of imaging and endoscopic findings. Mean insertion depth was 105.4 cm proximal to the ileocecal (IC) valve and mean procedure length was 39.9 minutes. There was a diagnostic yield of 43.9%, with an additional 12.1% of cases exhibiting colonic pathology. In 19.6% of cases, the endoscopist performed a therapeutic intervention, and in 34.6% of cases a tissue sample was obtained. There were no complications. Limitations: Single-center, retrospective design Conclusions: RSBE exhibited a high diagnostic yield for a seemingly safe and effective procedure, allowing for diagnostic and therapeutic interventions for a variety of small bowel diseases. Patient demographics and pre-procedural considerations. Age, years 57.3 16.2