Inflammatory markers for the early detection of post-operative infection: The same threshold for rectal and colic surgery?

Introduction: Anastomotic fistula is the most fearsome complication following colorectal surgery. Numerous studies have demonstrated the interest of postoperative CRP assay as an early diagnostic marker. Must the critical threshold for biological inflammatory markers remain the same, whether resection be colic or rectal?

Patients and method: This is a study based on a cohort constituted between 2011 and 2014, including 497 patients with planned colorectal resection. C-reactive protein and pro-calcitonin were measured daily from day before surgery to D4. All postoperative intra-abdominal complications were considered as an anastomotic fistula. Detection thresholds were calculated from the area under the ROC curve.

Results: An intra-abdominal septic complication occurred in 16.9% of the patients having undergone rectal resection vs. 9.9% of those having had colectomy (P=0.03). In the absence of complications there was no significant difference between the two groups in terms of postoperative inflammatory response as determined by either CRP or PCT assay. Following rectal resection, optimal area under the curve (AUC=0.87) corresponds to CRP on D4 for a threshold of 100mg/L: sensitivity 83.3%, NPV 95.3%. For colons with the same CRP at 100mg/L (AUC=0.71): sensitivity 63.6%, NPV 93.9%.

Conclusion: Notwithstanding riskier surgery, the detection threshold for an anastomotic fistula following rectal surgery remains the same: CRP>100mg/L at D4.