Computed Tomography Vs. Endoscopy Study

On day 3, 4 or 5 postoperatively, all patients with colorectal resection and anastomosis will undergo a CT scan with intravenous (i.v.) and rectal contrast enema and a flexible endoscopy. Both are currently routine examinations. CT scan is performed before endoscopy because contrast enema clears the rectum and anastomotic area and no further cleaning measures are necessary. The timing of the CT scan and the endoscopy is chosen because early signs of anastomotic leak should be present and thus early therapeutic interventions before the development of peritonitis is possible. The standard treatment is not altered with the exception of the two described procedures. Due to infrastructural issues and weekends the CT scan and the endoscopy can be performed on either day (3,4,5 postoperatively). The study is to start after Ethical approval. With a sample size of 400 patients, and an annual case load of 80-100 patients (minus drop outs of 10%), the study is planned to be finished (last patient processed) 31.12.2020. Data analysis and final processing will take another 6-8 months. All patients with colorectal disorders planned for surgery are seen in the outpatient clinic of one the four staff surgeons performing colorectal resections. This appointment is at least 1 week before surgery. During the appointment, patients are fully informed on the disease, indication, peri- and postoperative process and risk of treatment. During this visit eligibility is analysed, and information as well as informed consent are obtained. During the entire duration of the study, all serious adverse events (SAEs) that may be causally related to the study intervention are collected and documented in source documents. Reportable events are recorded in the case report form (CRF). Study duration encompassed the time from when the participant signs the informed consent until the last protocol-specific procedure has been completed, including a safety follow-up period. The analysis entails tests for paired categorical (McNemar test) and continuous (Student's independent t-test, Wilcoxon test) data. Sensitivity, specificity, positive and negative predictive value and accuracy will be calculated with 95% confidence interval. The significance level is set to p\<0.05.