The Tribune

By JEFFARAH GIBSON

Tribune Features Writer

jgibson@tribunemedia.net

INDIVIDUALS who are concerned about taking a colonoscopy exam can consider an alternative procedure that also detects precancerous growths and other diseases in the colon.

Virtual colonoscopy is different from colonoscopy, because it is a noninvasive medical imaging examination which uses x-rays and computers to produce images of the large intestine (colon). After a CT scan of the abdomen is obtained, the computer generates a detailed 3-D model of the colon, which the radiologist uses to view in a way that simulates travelling through the colon. The test can be used instead of a conventional colonoscopy to help detect cancers and other bowel conditions,” said Dr Amaresh Hombal, consultant radiologist at the Medical Pavillion.

Colon cancer refers to a malignant tumour arising from the inner wall of the large intestine. Once a colorectal cancer forms, it begins to grow in two ways. First, the cancer can grow locally and extend through the wall of the intestine and invade adjacent structures. Second, as the cancer grows it begins the process of metastasis, shedding thousands of cells a day into the blood and lymphatic system that can cause cancers to form in distant locations.

Major signs and symptoms of colon cancer include a persistent change in bowel habits, the presence of blood in the stool, abdominal discomfort or pain, bloating and unexplained weight loss.

One of the major reasons for performing a virtual colonoscopy is to screen for polyps or cancers in the large intestine. Polyps are growths that arise from the inner lining of the intestine and some may grow and turn into cancers. The goal of screening with VC is to find growths in their early stages, so that they can be removed before cancer has a chance to develop,” said Dr Hombal.

Taking either a colonoscopy or a virtual colonoscopy is the most effective way to prevent colon cancer, said Dr Hombal, while also encouraging individuals over age 50 and those who have a strong family history of the disease to be tested regularly.

“The American Cancer Society (ACS) recommends that women and men undergo screening for colon cancer or polyps beginning at age 50. ACS suggests a colonoscopy once every 10 years or a VC once every five years. Individuals at increased risk or with a family history of colon cancer may start screening at age 40 and may be screened at shorter intervals,” he said.

Dr Hombal said some people may opt to have a VC examine because it is more comfortable than conventional colonoscopy. Additionally, it does not involve inserting a tube all the way around the colon.

“No sedation is needed in VC and the patients can immediately return to their usual activities after the procedure. The lack of sedation also lowers the risk of the complications associated with it. It also takes less time than a conventional colonoscopy. The entire examination is usually completed within 15 minutes. VC also provides a secondary benefit of revealing diseases or abnormalities outside the colon,” said Dr Hombal.

“VC is strictly a diagnostic procedure and if any significant polyps or tumours are found, they will have to be removed by conventional colonoscopy. The ability of VC to differentiate stool from artefacts and detect smaller polyps may not be as good as that of conventional colonoscopy. VC is not recommended for patients who have active inflammation of colon, like colitis or diverticulitis, because of increased risk of perforating the colon. There is a small risk of getting cancer from exposure to radiation from VC, but the benefits far outweigh the risk,” he said.