Recent publications have questioned the safety and adequacy of cancer screening procedures particular mammograms, but today I am reviewing the risks of colonoscopies.
There is no doubt that colonoscopies can prevent colon cancer almost 100%.
We have learned over the last couple of years that the experience of the gastroenterologist is critical in identifying suspicious lesions. We have learned that lesions which are on the right side of the colon (farthest away from the anus) can be missed, particularly if they are not growths like polyps but flat lesions.
The key of the success of colonoscopies is how clean the colon is, since any remaining stool can mask small lesions.
Overall, colonoscopy is a very safe procedure, but as with any medical procedure, complications can occur. Studies have estimated the overall risk of complications for routine colonoscopy to be extremely low, at approximately 0.35 percent.
During colonoscopies where a polyp is removed (a polypectomy), the risk of complications is higher, although still very uncommon, at about 2.3 percent. In contrast, the lifetime risk for developing colon cancer is about 6 percent.
Complications during a colonoscopy can include perforation, bleeding, postpolypectomy syndrome, reaction to anesthetic, and infection. Complications during the prep for a colonoscopy are uncommon, but can occur, particularly in elderly patients, or in those with congestive heart failure.
We are particular worried about perforation, which is a tear or a hole in the gut. The risk of perforation is very low. A perforation can be caused by taking a biopsy from a thin point in the colon wall or when air introduced into the colon during the test to evaluate the intestinal lining better. We have seen that patients who have diverticula or diverticulitis may be at higher risk.
In recent years patients who are being treated for colon cancer with Avastin may be also at higher risk. Therefore, we are particularly careful in patients who receive Avastin. Usually we wait until treatment is completed or wait at least six weeks after the last Avastin dose or in patients with diverticulitis.
We also know that bleeding can occur after colonoscopies in about 1 out of every 1,000 colonoscopy procedures. The bleeding may be treated during the test, but in most instances, bleeding will resolve on its own. When a polyp is removed, there is a 30 to 50% chance that bleeding will occur anywhere from two to seven days after the colonoscopy. This type of bleeding may also resolve on its own, but may require treatment if it is severe.
If you experience any unusual pain after the procedure or you have ongoing bleeding please contact your physician.