Drain fluid's pH predicts anastomotic leak in colorectal surgery: results of a prospective analysis of 173 patients.

Abstract

The early risk assessment of anastomotic leak (AL) after colorectal surgery is crucial. Several markers have been proposed, including peritoneal fluid's pH. Aim of the present study is to evaluate the role of drain fluid pH as predictor of AL. All patients undergoing colorectal surgery from January 2015 to December 2017 were considered eligible. Hartmann procedures, procedures including temporary ileostomy and emergency surgery were excluded. Drain fluid was submitted for pH and chemical-physical assessment on postoperative day 1 (POD1) and postoperative day 3 (POD3). Out of 173 patients, those who developed AL showed a lower drain fluid's pH on POD1 and on POD3 compared to patients who did not (P<0.05). The plotted ROC curves identified 7.53 as pH cut-off on POD1 (AUC 0.80) and 7.21 on POD3 (AUC 0.86). With both the cut-offs, pH was an independent predictor of AL at multivariable analysis (P<0.001). pH<7.53 on POD1 and pH<7.21 on POD3 showed 93.75% sensitivity and 97% specificity respectively. Drain fluid's pH on POD1 is useful to select patients who will not develop AL while on POD3 it might identify those requiring a more careful management.