OBJECTIVETo evaluate the diagnostic value of dynamic monitoring of C-reactive protein (CRP) in drainage fluid in predicting early anastomotic leakage after colorectal surgery.

METHODSThis study enrolled 172 patients, who were diagnosed as colorectal cancer before operation and underwent radical surgery, without residual tumor tissues by postoperative pathology and perioperative infection, at the Tianjin Medical University Cancer Hospital between July 2015 and January 2016. The C-reactive(CRP) protein level in drainage fluid was continuously monitored from postoperative days (POD) 1 to 5. CRP level was compared between anastomotic leakage (AL) group and non-anastomotic leakage (NAL) group. Receiver operating characteristics (ROC) curve was used to estimate the value of monitoring CRP in drainage fluid to predict anastomotic leakage after colorectal surgery.

RESULTSAmong 172 patients, 101 cases were male and 71 cases were female, with age of (59.9±10.3) years. Anastomotic leakage occurred after colorectal surgery in 24 cases(14.0%, AL group ) and other 148 cases were defined as NAL group. Other than body mass index (BMI), differences in baseline data were not statistically significant between two groups. The CRP lever in AL group and NAL group showed rising trend from POD1 to POD4 [Day 1: (6.7±8.4) g/L vs. (8.0±10.6) g/L; Day 2: (24.8±14.6) g/L vs. (28.3±21.1) g/L, Day 3: (54.8±26.5) g/L vs. (53.8±27.6)g/L, Day 4: (62.0±32.2) g/L vs. (58.4±30.7) g/L], while the differences were not significant (all P>0.05). At POD 5, the CRP lever of AL group increased continuously, while that of NAL group decreased with significant difference [(65.3±38.9) g/L vs. (44.7±39.5) g/L, t=-2.85, P=0.005]. Further stratification analysis on AL group revealed CRP level in early AL (AL occurrence POD 10) showed rising trend from POD 1 to 4, then decreased slightly at POD 5, but whose differences were not significant (all P>0.05). ROC curve was drawn with AL condition as state variables and CRP level as test variables. The AUC of POD 1 to 4 was 0.425, 0.487, 0.510, 0.522 respectively and the AUC of POD 5 was the largest, 0.657 (95%CI:0.537-0.777). The largest Youden Index was 0.274. The critical value of CRP was 27.15 g/L. When this value was used as the point of tangency to predict the occurrence of AL, the sensitivity was 87.5%, the specificity was 39.9%, positive predictive value was 19.1%, and negative predictive value was 95.2%.

CONCLUSIONContinuous increase of CRP level in abdominal drainage fluid from POD 1 to POD 5 indicates the occurrence of AL after colorectal cancer operation, especially the detection of CRP level at POD 5 is important.