Polyps of the Colon and Rectum
What are polyps?
Polyps are abnormal growths rising from the lining of the large intestine (colon) and protruding into the intestinal canal (lumen). Some polyps are flat, others have a stalk. Polyps are one of the most common conditions affecting the colon and rectum, occurring in 15-20% of the adult population. Although most polyps are benign, the relationship of certain polyps to cancer is well established and some may be frankly malignant.
What are the symptoms of polyps?
Most polyps produce no symptoms and are often found incidentally during endoscopy or x-ray of the bowel. Some polyps, however, can produce bleeding, mucus discharge, alteration in bowel function, or in rare cases, abdominal pain.
How are polyps diagnosed?
Polyps are diagnosed either by looking at the colon lining directly (endoscopy) or by x-rays and scans.
There are three type of colorectal endoscopy:
- rigid sigmoidoscopy,
- flexible sigmoidoscopy and
- colonoscopy.
Rigid sigmoidoscopy permits examination of the lower 20-30 cms of the large intestine and is often performed in the office. Flexible sigmoidoscopy examines the rectum and lower 1/4 to 1/3 of the colon. Colonoscopy also involves a flexible instrument and usually permits inspection of the entire rectum and colon.
The colon can also be indirectly examined using the barium enema x-ray technique. This examination uses a barium solution to coat the colon lining. X-rays are taken, and unsuspected polyps are frequently found.
CT Colonography (virtual colonoscopy) is a new imaging technique for the bowel and is currently being evaluated. The accuracy for detection of polyps and cancers is unproven. Colonoscopy would then be required to remove polyps of the presence of pathology.
Although checking the stool for microscopic blood is an important test for colon and rectal disorders, a negative test does NOT rule out the presence of polyps. The discovery of one polyp necessitates a complete colon inspection, since at least 30% of such patients will have additional polyps.
Do polyps need to be treated?
Since there is no fool-proof way of predicting whether or not a polyp is or will be come malignant, total removal of all polyps is advised. The vast majority of polyps can be removed by snaring them with a wire loop passed through the instrument or by simply by touching them with a coagulating electrical current.
Most colonoscopy examinations including polyp removal, can be performed on an outpatient basis with minimal discomfort. Large polyps may require more than one treatment for complete removal. Some polyps cannot be removed by instruments because of their size or position and after discussion surgery might be required.
Can polyps recur?
Once a polyp is completely removed, its recurrence is very unusual. However, the same factors that caused the polyp to form are still present (whatever they may be). New polyps will develop in at least 30% of people who have previously had polyps.
