The National Institute for Health and Clinical Excellence (NICE) has issued full guidance to the NHS in England, Wales, Scotland and Northern Ireland on computed tomographic colonoscopy (virtual colonography).


CT colonography is used to examine the colon and rectum, and detect abnormalities such as polyps and cancer. Polyps are growths in the lining of the colon or rectum that protrude into the intestinal canal. They may be hyperplastic, which are completely benign or adenomatousin type, which have the potential to become malignant.

Conventional colonoscopy and double contrast barium enema are the main methods currently used for examining the entire colon. The bowel must be empty before either of these procedures is performed.

CT colonography is less invasive than a conventional colonoscopy. It involves using a CT scanner to produce 2- and 3-dimensional images of the entire colon and rectum.

CT colonography is performed on an empty bowel. Sedation is not usually required. The colon is distended by insufflation with air or carbon dioxide, via a small rectal tube. Antispasmodic agents and/or contrast agents may be administered intravenously before the scan. The CT scan is done with the patient holding his or her breath for approximately 20 seconds in both the supine and prone positions.

The images are then manipulated and interpreted by a radiologist.

Coding recommendations

U17.5 Computed tomography of colon                                                    

Y97. Radiology with contrast

Y98.1 Radiology of one body area (or < twenty minutes)

Note: A code from category Y97.- Radiology with contrast is only assigned if contrast is used