1. Addenbrooke’s Hospital Rosie Hospital DISCORDANCE BETWEEN SMALL BOWEL AND COLONIC BIOPSIES POST INTESTINAL TRANSPLANT Lisa Sharkey 1, Matthew Crowson 2, Charlotte Rutter 1, Susan Davies 3, Andrew Butler 2, Stephen Middleton 1 1 Department of Gastroenterology,, 2 Department of Transplant Surgery, 3 Department of Histopathology, Cambridge University Hospitals NHS Foundation Trust, Cambridge, United Kingdom Lisa.sharkey@addenbrookes.nhs.uk Introduction Small bowel (SB) and multivisceral transplant has been modified to include the ileocaecal valve and colon to improve quality of life by improving fluid balance and reducing stoma output. Endoscopic biopsy remains the method of choice for diagnosing acute cellular rejection (ACR). Assessing the SB via colonoscopy can often be challenging post transplantation and standardised histological criteria for rejection in colonic grafts have not yet been established. We present our concordance data of SB and colonic biopsy for assessing ACR. Methods We conducted a retrospective study of all patients receiving both a small bowel and colon transplant (including as part of a multivisceral graft) at our institution between January 2012 and December 2014, comparing paired biopsy results. The VIII International small bowel transplant symposium criteria 1 are used when reporting biopsy results. The categories used were no ACR (including indeterminate), borderline, mild, moderate and severe ACR. Biopsies were reviewed by one of the dedicated gastrointestinal pathologists. Results 19 patients received a colon- containing graft during the study period. 140 sets of paired ileal and colonic biopsies were examined. The majority (116/140, 83%) did not show any evidence of rejection. 34 biopsy sets did show some degree of ACR, of these only 10 were concordant as to the severity of rejection. When normal biopsy sets are excluded, the concordance rate between SB and colon histology falls to 29%. In 70% of the discordant cases (17/24), the SB severity was greater than the colon. E poster 231 Discussion The histopathological severity of rejection in ileal and colonic biopsies following transplantation is discordant in the majority of cases. In particular, the severity of changes seen in the colon may underestimate the degree of rejection in 70% of cases. Clinicians should continue to biopsy both the small bowel and colonic grafts to assess for rejection. References 1.Ruiz P, Bagni A Brown R, Cortina G, Harpaz N, Magid MS, Reyes J. Histological criteria for the identifications of acute cellular rejection in human small bowel allografts: results of the pathology workshop of the VIII International Small Bowel Transplant Symposium. Transplant Proc 2004;36(2):335-7 Figure 1:Simultaneous macroscopic images of the ileum (A) and colon (B) in a 60 year old female 8 months post transplant. She received a SB and colon graft for short bowel syndrome secondary to complicated pancreatitis and early intestinal failure associated liver disease. A B