The Postoperative Puzzle: Early Biomarkers of Anastomotic Leak in Colorectal Surgery

Theresia Baumgartner¹, Tobias Meier²,Mark Vogel³

Abstract

Background: Anastomotic leak (AL) is one of the most feared complications following colorectal surgery, significantly increasing morbidity and mortality. Early detection remains a clinical challenge. This study evaluates the predictive value of serum and drain biomarkers in the first 72 hours post-surgery for early identification of AL.
Methods: A prospective cohort study was conducted across four surgical centres in Germany between 2022 and 2024. A total of 386 patients undergoing elective colorectal resection with anastomosis were enrolled. C-reactive protein (CRP), procalcitonin (PCT), interleukin-6 (IL-6), and drain amylase were measured at 24, 48, and 72 hours postoperatively. Clinical diagnosis of AL was confirmed by imaging or reoperation. Receiver operating characteristic (ROC) analysis was performed to evaluate diagnostic accuracy.
Results: Anastomotic leak occurred in 36 patients (9.3%). At 48 hours, IL-6 >180 pg/mL had the highest predictive accuracy (AUC = 0.86), followed by CRP >145 mg/L (AUC = 0.81) and PCT >0.9 ng/mL (AUC = 0.78). Drain amylase levels were significantly elevated in rectal surgeries with AL (mean 622 IU/L vs. 188 IU/L, p < 0.001). A combined biomarker score (IL-6 + CRP) yielded an AUC of 0.91 with 88.4% sensitivity and 83.1% specificity.
Conclusion: Measuring IL-6 and CRP within 48 hours postoperatively offers a reliable, noninvasive strategy for early detection of anastomotic leaks in colorectal surgery. The routine integration of biomarker panels may enable earlier intervention, reduce complications, and improve recovery trajectories.