Procalcitonin and C-reactive protein as early markers of postoperative intra-abdominal infection in patients operated on colorectal cancer

The aim of this study was to evaluate the accuracy of serum procalcitonin (PCT) and C-reactive protein (CRP) for early diagnosis of postoperative intra-abdominal infections (PIAI) after elective surgery for colorectal cancer.

Prospective observational study including patients operated on for colorectal cancer between January and December of 2015 was performed. Serum PCT and CRP levels were measured before surgery and daily until postoperative day 3.

One hundred twenty patients were included. Seven patients (5.8%) had PIAI. PCT levels were significantly higher in patients with PIAI on postoperative days 1 and 3, whereas CRP levels only were significantly more elevated on postoperative day 3. The ratio between CRP levels on postoperative day 3 and CRP levels on postoperative days 2 (CRP D3/CRP D2) and 1 (CRP D3/CRP D1) was significantly higher in patients with PIAI. PCT on postoperative day 3, for a cutoff of 0.45 ng/mL, had the best sensitivity (100%) with a specificity of 73.8%. The ratio CRP D3/CRP D1 yielded the higher specificity and positive predictive value (90.9 and 27.3%, respectively, for a cutoff of 1.8). The higher negative predictive value was obtained for PCT on postoperative days 1 and 3 (100%, with cutoff of 0.76 and 0.45 ng/mL, respectively) and for CRP on postoperative day 3 (100% with cutoff of 10 mg/dL).

PCT and CRP serum levels are associated with the appearance of PIAI after colorectal cancer surgery, although the positive predictive values were low for both PCT and CRP. However, the negative predictive values were high.