The added clinical value of performing CT colonography in patients with obstructing colorectal carcinoma

Background: A small percentage of incomplete optical colonoscopies (OCs) are the result of an obstructing tumor. According to current guidelines, CT colonography (CTC) is performed to prevent missing a synchronous tumor. The aim of this study was to evaluate how frequently a synchronous tumor was found on CTC and how often this led to a change in the surgical plan.Methods: In this retrospective study, a total of 267 patients underwent CTC after an incomplete OC as a result of an obstructing colorectal carcinoma (CRC). Among them, 210 patients undergoing surgery met the inclusion criteria and were included in the analysis. The OC report, CTC report and surgical report of these patients were retrospectively evaluated for the presence of synchronous tumors using surgery and post-operative colonoscopy as the gold standard.Results: Six of the 210 patients (2.9%) showed signs of a synchronous CRC proximal to the obstructing tumor on CTC. In three of these patients, a synchronous CRC was confirmed during surgery. All these tumors caused a change in the surgical plan. Three out of the six tumors found on CTC were found to be large, non-malignant polyps. All these polyps were located in the same segment as the obstructing tumor and therefore did not alter the surgical plan.Conclusion: In patients with obstructing CRC, the frequency of synchronous CRCs proximal to this lesion is low. Performing a CTC leads to a change in surgical plan based on the presence of these synchronous tumors in 1.4% of the cases. CTC should be employed as a one-stop shop in patients with an obstructing CRC.