March is National Colorectal Cancer Awareness Month: Do You Know What Your Screening Op...(ema with air contrast: A chalky sub...),Health

A chalky substance, which shows up on X-ray, is given as an enema. Air is then pumped into the colon causing it to expand. This allows X-ray films to take pictures of the colon. Laxatives must be used the night before the exam to clean the colon.

PROS:

• Done without sedation
• Very low risk

CONS:

• Uses X-ray radiation
• Can miss larger polyps and growths (over 50 percent polyps 1 cm, and 15 percent of cancers)
• If polyps are found, the patient must be followed up with a colonoscopy

CT COLONOGRAPHY (also referred to as virtual colonoscopy) A small tube is placed in the rectum and air is pumped into the colon to inflate the bowel. Then a special CT scan is used to image the colon. Recent studies show that it is effective in identifying medium to large polyps, but is ineffective in identifying small polyps. CT colonography may be best for low-risk patients who cannot undergo colonoscopy or who have had an incomplete colonoscopy due to various factors. The same bowel prep as conventional colonoscopy is required and it does not use sedation.

PROS:

• Examines the entire colon
• High detection rate for medium to large polyps
• Low risk

CONS:

• Air distention of the bowel can be uncomfortable
• Ineffective in detection of small polyps
• Uses X-ray radiation
• If polyps or other abnormalities are found, a colonoscopy must be performed
• Is not covered by Medicare as an initial screening test
• Is not recommended by ASGE screening guidelines or the U.S. Preventive Services Task Force (USPSTF) recommendat
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