CT colonography even safer than previously thought

The safety profile for CT colonography (CTC) is extremely favorable, particularly for the purposes of screening patients with no symptoms and when distending the colon using an automated carbon dioxide technique, a finding that goes against the higher complication rates for CTC reported by other groups, according to a new study.

For this study, researchers analyzed 21,923 CTC procedures, including both diagnostic and screening procedures. Colonic distention was achieved by manual room air insufflation in 60% of cases and by automated carbon dioxide delivery in 40%. No perforations were recorded in patients undergoing screening CTC or with those who underwent the automated carbon dioxide delivery technique. Perforations were recorded in only two patients undergoing diagnostic CTC, and manual room air insufflation was employed in both cases. Only one of the two needed treatment for the perforation, and the one who was treated was already symptomatic prior to CTC due to annular sigmoid carcinoma. Overall, the researchers found that the complication rate for this procedure was 0.018%, or 4 out of 21,923 procedures.

According to the researchers, automated carbon dioxide delivery is much simpler and safer for the CT technologist to employ than manual room air insufflation, which was the method of distention used in the previous studies that reported a higher complication rate due to perforations. "The automated nature of carbon dioxide delivery removes the guesswork and patient coaching necessary with manual distention. In addition, this automated approach with low-pressure carbon dioxide provides improved distention and reduced post-procedure discomfort," said Perry J. Pickhardt, MD, of the University of Wisconsin Medical School and lead author of the study.

"Our results provide reassurance to patients that this minimally invasive examination is a very safe colorectal screening tool. 'Primum non nocere' (first do no harm) is particularly applicable to the screening of asymptomatic adults, which raises some important issues for screening with invasive colonoscopy," said Dr. Pickhardt.

The full results of the study were presented on May 2, 2006 during the American Roentgen Ray Society Annual Meeting in Vancouver, BC.