Physiological changes after colorectal surgery suggest that anastomotic leakage is an early event: a retrospective cohort study

AIM: Anastomotic leakage (AL) is often identified 7-10 days after colorectal surgery. However, in retrospect, abnormalities may be evident much earlier. This study aims to identify the clinical time point when AL occurs.

METHOD: This is a retrospective case-matched cohort comparison study, assessing patients undergoing left-sided colorectal resection between 2006 and 2015 at a specialist colorectal unit. Patients who developed AL (LEAK) were case-matched to two CONTROL patients by procedure, gender, laparoscopic modality and diverting stoma. Case note review allowed the collection of basic observation data and blood tests (leukocyte count, C-reactive protein, bilirubin, alanine transaminase, creatinine) up to postoperative day (POD) 4. The cohorts were compared, with the main outcome measure being changes in basic observation data.

RESULTS: Of 554 patients, 49 developed AL. These were matched to 98 CONTROL patients. Notes were available for 105 patients (32 LEAK/73 CONTROL). Groups were similar in demographics, tumour or nodal status, preoperative radiotherapy, intra-operative air-leak integrity and drain usage. AL was detected clinically at a median of 7.5 days postoperatively. There was a significantly increased heart rate by the evening on POD 1 in LEAK patients (82.8 ± 14.2/min vs 75.1 ± 12.7/min, P = 0.0081) which persisted for the rest of the study. By POD 3, there was a significant increase in respiratory rate (18.0 ± 4.2/min vs 16.5 ± 1.3/min, P = 0.0069) and temperature (37.0 ± 0.4C vs 36.7 ± 0.3C, P = 0.0006) in LEAK patients. C-reactive protein was significantly higher in LEAK patients from POD 2 (165 ± 95 mg/l vs 121 ± 75 mg/l, P = 0.023).

CONCLUSIONS: Physiological and biochemical changes associated with AL happen very early postoperatively, suggesting that AL may occur within 36 h after surgery, despite much later clinical detection.