Virtual colonoscopy – pto
Virtual colonoscopy has been recently adopted as an acceptable alternative ro colonsocopy and barium enema for colorectal cancer screening. It examines the colon and rectum, and it can detect abnormalities such as polyps and cancer. CT colonography is less invasive than a conventional colonoscopy and does not require passing a scope into the bowel. It involves using a CT scanner to produce 2- and 3-dimensional images of the entire colon and rectum. On the other hand, ti does not allow a biopsy when an abnormality is visualized and requires another colonoscopy in such cases. CT colonography requires the same amount of bowel preparation, such as liquid diets and strong laxatives on the day before the test, as traditional colonoscopy. The test may also miss some smaller, possibly pre-cancerous polyps that would likely be caught and removed during colonoscopy. While the risk is hard to assess, the test does expose patients to a low level of radiation.
Guidelies disagree. NICE supports it while The California Technology Assessment Forum (CTAF) concluded that virtual colonoscopy for colorectal cancer screening does not meet CTAF criteria (Walsh, 2009). On May 12, 2009, the Centers for Medicare & Medicaid Services (CMS) issued a final coverage determination that refused coverage of CT colonography for colorectal screening. It stated that the evidence is inadequate to conclude that CT colonography is an appropriate colorectal cancer screening test. NCCN supports it every 5 years if no polyps are detected (CSCR-A,). Interqual 2011 recommended it ifor screening over age 50 and in the situation of failed colonoscopy. It appears reasonable to use this technique for situations such as : symptomatic patients who are unable to undergo a complete colonoscopy (such as individuals with an obstructive tumor and others who may be unable to tolerate the procedure) or on anticoagulation therapy who cannot safely discontinue treatment and would be at risk of bleeding from a more invasive procedure.
FOr Lay version see here
http://guidance.nice.org.uk/IPG129, 2013
C. Daniel Johnson et al, Accuracy of CT Colonography for Detection of Large Adenomas and Cancers , 2008 New England Journal of Medicine (Vol. 359, No. 12: 1207-1217). ,
Pickhardt PJ, Hassan C, Halligan S, Marmo R. Colorectal Cancer: CT Colonography and Colonoscopy for Detection Systematic Review and Meta Analysis. Radiology. 2011; 259(2):393 -405.
Hayes, Inc. Medical Technology Directory. Computed Tomography Colonography (Virtual Colonoscopy).
Landsdale, PA: Hayes, Inc., March 13, 2008.
Walsh J. Computed tomographic colonography (virtual colonoscopy) for colorectal cancer screening in average risk individuals. Technology Assessment. San Francisco, CA: California Technology Assessment Forum (CTAF); March 11, 2009. Available at: http://ctaf.org/content/assessment/detail/989.
Ontario Ministry of Health and Long-term Care, Medical Advisory Secretariat (MAS). Computed tomographic (CT) colonography for colorectal cancer screening: An evidence-based analysis. Ontario Health Technology Assessment Series. Toronto, ON: Medical Advisory Secretariat (MAS); 2009;9(7).