Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 34 Supple 1 2005 03 15 68 69 M Aarabi A Bahari M Hedayati A Jarollahi M Habibi R Aghazadeh MR Zali 2015 10 03 Introduction: Inflammatory bowel disease (IBD) has two major groups: Ulcerative Colitis (UC) and Crohn’s Disease (CD), diagnosed by routine invasive methods. In recent years, diagnostic value of immunologic tests including perinuclear Antineutrophil Cytoplasmic Antibody (pANCA) and Anti-Saccharomyces Cerevisiae Antibody (ASCA) has been mentioned. These tests are supposed to be used as a diagnostic tool and also have some relationship with clinical characteristics of IBD.In this study; we investigated the diagnostic value of above tests and their relationship with IBD manifestations. Methods: Sera from 144 patients with IBD (113 with UC and 31 with CD) as cases and 176 patients with non-IBD rectorrhagia, flatulence, dyspepsia, GI cancers, IBS as controls were analyzed. Patients’ serum was assayed for ASCA by Enzyme-Linked Immunosorbent Assay (ELISA) & for pANCA by indirect immunofluorescence assay (IFA). Results: Sensitivity, specificity, positive and negative predictive value of pANCA in UC were: 39%, 82%, 70%, and 56%. In patients with CD the above parameters were: 58%, 70%, 31%, and 87%, respectively. Using both tests increased the specificity and positive predictive value in UC patients to 89% and 84% and in patients with CD to 80% and 46%. There was a significant difference between CD and UC groups in ASCA results (P= 0.002).UC patients with Sclerosing Cholangitis (P=0.003) and severe bleeding (P=0.004) were significantly positive for pANCA more than other UC patients, respectively. Conclusion: We recommend pANCA & ASCA for differentiation of CD & UC, although it is not useful for screening. Using both tests together improves the specificity and positive predictive value. Positive pANCA results might be seen together with some complications like: Sclerosing Cholangitis & severe bleeding. https://ijph.tums.ac.ir/index.php/ijph/article/view/3000