Extracolonic and incidental findings on CT colonography (virtual colonoscopy)

The objective of our study was to prospectively determine the frequency and clinical importance of extracolonic findings on CT colonography in symptomatic patients. SUBJECTS AND METHODS. One hundred eleven symptomatic patients referred for colonoscopy underwent CT colonography before colonoscopy. Helical CT from the diaphragm to the symphysis was performed with the patient in the supine and prone positions after rectal air insufflation. Image interpretation was done on a digital workstation. Extracolonic findings were classified as minor, moderate, or major according to potential clinical importance. Patient records, with a follow-up time of about 3 years, were reviewed to determine final diagnoses.

Twenty-six (23%) of the patients had CT findings of major importance such as lymphadenopathy (n = 7), aortic aneurysm (n = 6), suspected solid hepatic masses (n = 5), and suspected solid renal masses (n = 4). Fifty-eight patients (52%) had findings of moderate importance such as gallstones (n = 16), indeterminate renal masses (n = 9), adrenal masses with benign appearance (n = 8), and hiatal hernia (n = 7). Forty-six patients (41%) had no or only minor findings, such as renal cysts (n = 34), renal calcifications (n = 19), and hepatic cysts (n = 14). Review of patient records showed that CT colonography contributed to the detection of major, previously unknown extracolonic disorders in 14 (13%) of the 111 patients.

Potentially important extracolonic findings were revealed in 23% of the patients, leading to additional diagnostic or therapeutic considerations. Some of these findings were clinically important, whereas others were previously known or led to unnecessary workup. This finding must be taken into account when CT colonography is considered for routine diagnostic workup or screening.