P0516Do Crohn’s Patients Require Higher CRP Thresholds following Bowel Resection to Detect Anastomotic Leak? A Retrospective Analysis

Background Anastomotic leaks following colorectal resection are linked with high morbidity and mortality; therefore, early detection is essential. C-reactive protein (CRP) is widely used to screen for postoperative complications such as an anastomotic leak [1]. Typically, a CRP level exceeding 150 mg/l on postoperative day (POD) 3-4 would prompt further investigation. In Crohn’s disease (CD), however, underlying chronic inflammation may lead to higher postoperative CRP levels even in uncomplicated cases, potentially reducing the specificity of the standard CRP threshold [2]. This study evaluated postoperative CRP in CD patients undergoing bowel resection to determine whether the standard CRP threshold reliably identifies early anastomotic leaks. Methods This retrospective review was conducted of all CD patients who underwent emergency or elective bowel resection with anastomosis between 2020 to 2025 at University Hospitals Birmingham, UK. Collected variables included postoperative CRP (POD 1-10), demographics, operative details, preoperative steroid/biologic use, and postoperative complications. Patients were categorised according to the presence of an anastomotic leak. CRP trajectories were compared using Mann-Whitney U tests. Diagnostic accuracy was evaluated via ROC analysis and the Youden index was applied to identify the optimal POD 4 CRP threshold for this cohort. Results A total of 129 patients were included, of which 9 (7%) developed an anastomotic leak. Patients with leaks exhibited consistently higher CRP levels from POD 1 onwards, with the greatest divergence seen between POD 3-6. Significant differences in CRP were seen on POD 1 (167 vs 100 mg/l, p = 0.028), POD 4 (327 vs 184 mg/l, p = 0.0048), POD 6 (270 vs 138 mg/l, p = 0.028), and POD 9 (172 vs 83 mg/l, p = 0.044). In the non-leak group, the average CRP exceeded 150 mg/L on POD2-4 (180–194 mg/L), showing that the usual 150 mg/L threshold is commonly surpassed even without complications. ROC analysis demonstrated CRP showed its highest diagnostic accuracy on POD 4 and POD 6 (AUC 0.83 and 0.84), indicating these were the most reliable days for identifying an anastomotic leak. The optimal POD 4 CRP threshold for leak detection was 279 mg/L (250-300 mg/L) (sensitivity 86%; specificity 86%), indicating strong utility in ruling out leaks. Conclusion Postoperative CRP remains a clinically useful biomarker for detecting anastomotic leaks in CD; however, conventional cut-offs around 150 mg/L lack specificity in this population. CD patients exhibit higher postoperative CRP levels even in the absence of complications. A disease-specific POD 4 threshold of 250-300 mg/L provides substantially improved diagnostic accuracy and may better guide early postoperative decision-making. References: 1. Yeung DE, Peterknecht E, Hajibandeh S, Hajibandeh S, Torrance AW. C-reactive protein can predict anastomotic leak in colorectal surgery: a systematic review and meta-analysis. Int J Colorectal Dis. 2021;36(6):1147-1162. doi:10.1007/s00384-021-03854-5. 2. Slavin M, Goldstein A, Raguan B, Rudnicki Y, Avital S, White I. Postoperative CRP levels can rule out anastomotic leaks in crohns disease patients. J Pers Med. 2022;12(1):54. Published 2022 Jan 5. doi:10.3390/jpm12010054. Conflict of interest: Ms. Akmal, Kiran: No conflict of interest Cunha, Melissa: No conflict of interest