Colorectal cancer (CRC) is the second most common cause of cancer-related death in the Western world, with 500000 deaths per year worldwide. Colonoscopy is accepted as a primary CRC screening tool in many countries. As a preventative procedure, its main purpose is to enable the early diagnosis of CRC at a curable stage and to identify and remove pre-malignant adenomas. Cecal intubation is associated with an increased detection rate of advanced neoplasia, as 33-50% of advanced neoplasia is located in the proximal colon. Complete colonic evaluation is therefore a well-recognized measure of colonoscopy quality control. Cecal intubation rates of ≥ 90% of all colonoscopies in routine clinical practice and ≥ 95% in screening colonoscopies are recommended. Unfortunately, the cecal intubation rate in daily clinical practice is often lower than the target of ≥ 90%, with reported percentages varying from 76.9% to 98.4%. This means that after an incomplete colonoscopy, malignant and pre-malignant lesions may be missed if further investigation is not pursued. Several explanatory factors for incomplete colonoscopy have been described. Patient factors that have been shown to increase the risk of an incomplete examination include advanced age, female sex, previous abdominal/pelvic surgery, and diverticular disease. After an incomplete conventional colonoscopy, patients are required to undergo another test to complete the visualization of the colon. Options for incomplete examinations because of anatomic reasons include both radiologic and endoscopic means.

CT Colonography (CTC ) permits to visualise the whole colon, is minimally invasive, does not require sedation and is well accepted by the patient.

The present role of CTC is the integration as a replacement for barium enema in the case of incomplete colonoscopy. In fact ,since 2006 the American Gastroenterological Association (AGA) Clinical Practice and Economics Committee has endorsed CTC as the method of choice for colon investigation in cases of incomplete colonoscopy and numerous evidence exists in the literature showing a clear superiority of CTC over Barium Enema in the detection of CRC and polyps.

Two large, multicenter trials \[the American College of Radiology Imaging Network (ACRIN) trial performed in the USA and Italian Multicenter Polyps Accuracy CTC study (IMPACT)trial testing the performance of CTC in comparison with conventional colonoscopy reported that a negative predictive values in both trials for CTC approaching 100%; this is extremely important in order to reassure negative patients about the significance of the examination.The PillCam Colon Capsule Endoscopy (Given® Diagnostic System)offers an alternative approach for endoscopic visualization of the colon in patients with an incomplete conventional colonoscopy. Advantages of the PillCam Colon Capsule Endoscopy (PCCE) include the elimination of the need for sedation, the minimally invasive, painless nature of the exam, no need of X-rays and the ability to pursue normal daily activities immediately following the procedure. Furthermore, PCCE may be well accepted by the subjects, thereby improving subjects' willingness to undergo a second diagnostic evaluation of the colon after the failure of the first endoscopic examination and comply with colorectal cancer screening recommendations. This is a study that is designed to evaluate the performance of the PCCE in the evaluation of patients with an incomplete colonoscopy, compared to the CT-colonography. PCCE and CT-colonography procedures will be compared in regards to completeness of the procedure and detection of lesions in the colon that would have been missed by the incomplete conventional colonoscopy.