The understanding of the mesorectal spread in rectal cancer has lead to wide acceptance of total mesorectal excision (TME) as the surgical technique of choice for carcinoma in the lower and mid rectum. While oncological results and survival have improved with TME-surgery, morbidity and mortality remain important issues. The most feared complication is symptomatic anastomotic leakage. The aim of this thesis was to focus on the role of the defunctioning stoma, risk factors, and postoperative monitoring in regard to anastomotic leakage in sphincter saving resection of the rectum.

Intraoperative adverse events were analysed in a retrospective population based case-control study in which all patients who underwent elective anterior resection in Sweden between 1987 and 1995, and who died within 30 days or during the initial hospital stay (n=140), were compared with patients chosen at random (n=423) who underwent the same operation during the same period, but survived the operation. Intraoperative adverse events were more frequent in those who died, and reconstruction of an anastomosis judged unsatisfactory by the surgeon improved the outcome.

In a population based retrospective case-control study, risk factors for symptomatic anastomotic leakage were investigated in randomly chosen sample of patients who underwent anterior resection in Sweden between 1987 and 1995 (n=432). Twelve per cent of the patients developed symptomatic leakage, and 25% of the patients with leakage ended up with a permanent stoma. In multivariate regression analysis, low anastomosis, preoperative radiotherapy, male gender and intraoperative adverse events were independent riskfactors for anastomotic leakage.

In a randomised multicentre trial patients operated with sphincter saving TME¨surgery for rectal cancer were randomised to a defunctioning stoma (n=116) or not (n=118). The overall rate symptomatic leakage was 19%. Patienst without a defunctioning stoma leaked in 28% and patients with a defunctioing stoma in 10%, a statistically significant difference (p<0.001) not previously demonstrated in any randomised trial of adequate size.

Postoperative monitoring with computed tomography scan (CT-scan) on postoperative day 2 and 7, and C-reactive protein (CRP) daily in 33 patients operated on with anterior resection of the rectum, demonstrated larger pelvic fluid collections in patients with leakage before the leakage was clinically diagnosed. CRP was increased from postoperative day 2 and onwards in patients in whom clinical leakage was diagnosed on median postoperative day 8.

In 23 patients who underwent anterior resection of the rectum, intraperitoneal metabolism was investigated using microdialysis technique measuring the carbohydrate metabolites lactate, pyruvate and glucose. Intraperitoneal cytokines IL-6, IL-10 and TNF-α were collected through a pelvic drain and analysed. In patients who developed leakage, the latate/pyruvate ratio was increased near the anastomosis on postoperative day 5 and 6, as well as IL-6 and IL-10 which were increased postoperatively day 1 and 2, while TNF-α was higher on day 1.