Anastomotic leakage is a serious complication after LAR with high morbidity and mortality rates. Early diagnosis and treatment is mandatory. The primary aim of the present study is to investigate the clinical use of peritoneal microdialysis and whether is able to detect anastomotic leakage prior to clinical symptoms develops.

Patients undergoing LAR for recto-sigmoid cancer is subjected to peritoneal microdialyses during the postoperative period until discharge. Subcutaneous microdialysis serve as control. Samples are collected every 4-hour. Samples will be analyzed continuously but the results will not be included in the clinical evaluation of the patient.

Patients undergoing abdomino-perineal rectal resection will serve as a control group.

A total of 50 patients will be included in this pilot study. The results of the peritoneal microdialyses will be compared with the clinical course in each patient. The results form the uncomplicated courses will be used to define the normal variations in peritoneal microdialysis. This will be compared to results from patients with various complications.

The study is approved by the local scientific ethical committee No. ------

Inclusion Criteria:

• Histological verified cancer
• The cancer must be located in rectum or the sigmoid colon
• Diverting stoma is allowed
• Perioperative radio-chemotherapy is allowed

Exclusion Criteria:

• Disseminated cancer
• ASA-group 4 ore higher

Patients undergoing Loa Anterior Resection (LAR) or rectal cancer