• Pros. Sedation isn't usually needed. Biopsies can be taken through the scope during the exam. The exam typically takes about 15 to 20 minutes.
  • Cons. Typically one or more enemas are done before the procedure to empty the lower part of the colon. In some cases, you might not be able to eat solid food the day before the exam. The exam doesn't allow the doctor to see the entire colon, so any cancers or polyps farther into the colon can't be detected. Rare complications may include bleeding from the biopsy site or a tear in the lining of the colon. Cramping or bloating might occur after the exam. Additional tests might be necessary if an abnormality is detected.

What's the bottom line?

Choosing a colon cancer screening test isn't always an easy decision, but it's a potentially lifesaving one. Consult your doctor about your colon cancer screening options. Commit to a screening schedule based on your personal risk factors. Remember, the earlier colon cancer is detected, the easier it is to treat.

Source: http://www.mayoclinic.org/diseases-conditions/colon-cancer/in-depth/colon-cancer-screening/art-20046825/