C-reactive protein as an early marker of anastomotic leak after elective intestinal transit restoration surgery: a retrospective study in Hidalgo, Mexico

Background: Anastomotic leak is one of the most serious complications of intestinal surgery, and its early diagnosis remains difficult in hospitals with limited access to imaging. This study evaluated whether a serum C-reactive protein (CRP) concentration above 135 mg/l on postoperative day 3 is associated with anastomotic leak after elective intestinal transit restoration surgery. Methods: This observational, retrospective study reviewed the clinical and laboratory records of adults who underwent elective intestinal transit restoration at the Dra. Columba Rivera Osorio General Hospital, Pachuca, Hidalgo, Mexico, between January 2021 and January 2024. CRP on postoperative day 3 was dichotomised at 135 mg/L and cross-tabulated against anastomotic leak. Association was tested with the Chi-square test (α=0.05) and its strength with Cramér’s V. Results: Of 50 records reviewed, 36 patients were included. Anastomotic leak occurred in 6 patients (16.7%) and CRP exceeded 135 mg/l in 10 (27.8%). All six patients with a leak had CRP above the cut-off, and no leak occurred among the 26 patients below it. The association was significant (χ²=18.72, p<0.001) and strong (Cramér’s V=0.72); sensitivity was 100%, specificity 86.7%, positive predictive value 60% and negative predictive value 100%. Type of anastomosis, anastomotic site and underlying diagnosis were not associated with leak. Conclusions: A CRP above 135 mg/l on postoperative day 3 was strongly associated with anastomotic leak. As a low-cost, widely available test, CRP may serve as an early warning and rule-out tool in resource-limited hospitals, complementing clinical assessment and imaging. Larger prospective studies should validate this cut-off.