BACKGROUND Endovascular aortic repair (EVAR) is nowadays the standard procedure in treating patients diagnosed with abdominal pathologies with suitable anatomy. Open surgery remains an option mostly for patients not suitable for endovascular surgery. Colonic ischemia is an important and life-threatening postoperative complication of these procedures. OBJECTIVE The aim of this study is to evaluate the clinical value and safety of performing a planned sigmoidoscopy and biopsy for detection of colonic ischemia in patients undergoing elective aortic surgery. We also aim to develop prediction scores which could identify patients at risk for CI and facilitate their timely treatment. METHODS The trial is designed as a prospective study. The decision for aortic surgery is taken and eligibility for these procedures is ascertained according to current guidelines. Afterwards, screening of the patient for the remaining inclusion and exclusion criteria takes place. If eligibility for study inclusion is confirmed, the patient is informed about the aims of the study and all study-specific procedures (sigmoidoscopy and biopsy) and asked to provide informed consent. We assume that the rate of colonic ischemia diagnosed within 48 hours after the operation would be increased by 10% by means of sigmoidoscopy in asymptomatic patients. 120 cases undergoing sigmoidoscopy would allow for a comparison to the incidence of colonic ischemia after aortic surgery reported in the literature (5%) with alpha = 5 % and the statistical power (1-beta) = 80%. RESULTS This study will provide insight on the clinical value and safety of performing a sigmoidoscopy and biopsy for detection of colonic ischemia in patients undergoing elective aortic surgery. If the present study showed that sigmoidoscopy can be performed safely and is effective for diagnosing colonic ischemia in these patients, this could result in its routine implementation in both elective and emergency settings. CONCLUSIONS If the present study will show that sigmoidoscopy can be performed safely and is effective for diagnosing colonic ischemia in these patients, this could result in its routine implementation in both elective and emergency settings. CLINICALTRIAL DRKS-ID: DRKS00025587