Colonic polyps, also known as colorectal polyps, are growths that appear on the surface of your large intestine, or colon. You can have more than one polyp, and they may be flat or raised, benign or cancerous.
According to the National Institute of Diabetes and Digestive and Kidney Diseases, polyps that are flat may are more likely to be cancerous in comparison to raised polyps. (NIDDK)
Although polyps may sometimes be an indicator of colon cancer, it is important to distinguish these two conditions:
Not everyone who has polyps will also develop colon cancer. However, removing potentially cancerous polyps may reduce your risk of developing colon cancer.
What Causes Colonic Polyps and Who Is at Risk?
Doctors are not sure what causes colonic polyps. When polyps are cancerous, they may be linked to colon cancer though this is not the sole cause of the polyps.
However, having certain risk factors and engaging in some unhealthy behaviors are thought to make colonic polyps more likely.
You may have a higher risk if:
- you have a family history of polyps or colon cancer
- you have had polyps previously
- you have had ovarian or uterine cancer before the age of 50
- you are 50 years old or over
Unhealthy behaviors that may contribute to the growth of colonic polyps include:
- being overweight
- drinking alcohol
- exercising infrequently
- eating a diet rich in fats
If you make lifestyle changes to address these behaviors, you may be able to reduce your risk. Additionally, regularly taking a low dose of aspirin and adding more calcium to your diet may help prevent polyps.
Your doctor may have other suggestions for reducing your risk.
Symptoms and Signs
Most polyps are asymptomatic. Rectal bleeding, usually occult and rarely massive, is the most frequent complaint.
Cramps, abdominal pain, or obstruction may occur with a large lesion. Rectal polyps may be palpable by digital examination.
Occasionally, a polyp on a long pedicle may prolapse through the anus. Large villous adenomas may rarely cause watery diarrhea that may result in hypokalemia.
Diagnosing and Treating Colonic Polyps
Your doctor may use a combination of tests to discover if you have colonic polyps. These tests may include:
- colonoscopy—a camera on a flexible tube is threaded through the anus to view the rectum and colon
- sigmoidoscopy—similar to colonoscopy but shows only the rectum and lower colon
- barium enema—an X-ray of the colon after it is injected with barium, which helps make images more visible
- computed tomography (CT) scan—a tube with a camera, X-rays, and computers work together to create images of your large intestine. This is sometimes called a virtual colonoscopy.
- stool test
One of the procedures done to confirm a diagnosis of colonic polyps is the same one used to treat them. Polyps are removed during a colonoscopy.
The colonoscopy tube has a polyp-removal tool in addition to a camera. Doctor will usually remove any polyps they find as they are checking the large intestine.
Polyps are then tested for cancer unless your doctor has already determined that they are benign.
Polyps should be removed completely with a snare or electrosurgical biopsy forceps during total colonoscopy; complete excision is particularly important for large villous adenomas, which have a high potential for cancer.
If colonoscopic removal is unsuccessful, laparotomy should be done.
Tattooing the distal margin of the polyp with India ink helps the surgeon locate the polyp during laparotomy.
Subsequent treatment depends on the histology of the polyp. If dysplastic epithelium does not invade the muscularis mucosa, the line of resection in the polyp’s stalk is clear, and the lesion is well differentiated, endoscopic excision and close endoscopic follow-up should suffice.
Patients with deeper invasion, an unclear resection line, or a poorly differentiated lesion should have segmental resection of the colon.
Because invasion through the muscularis mucosa provides access to lymphatics and increases the potential for lymph node metastasis, such patients should have further evaluation (as in colon cancer—see Colorectal Cancer).
The scheduling of follow-up examinations after polypectomy is controversial and varies by the number, size, and type of polyps removed.
Most authorities recommend total colonoscopy annually for 2 yr (or barium enema if total colonoscopy is impossible), with removal of newly discovered lesions. If 2 annual examinations are negative for new lesions, colonoscopy is recommended every 2 to 3 yr.
Current cost containment recommendations extend the interval between colonoscopies to 5 yr or longer, which some practitioners argue is not necessarily best practice.
What Are Recovery Expectations For Colonic Polyps?
Colonic polyps are usually noncancerous and are considered harmless. Removing polyps may reduce or eliminate any related symptoms you were experiencing and may help to prevent colon cancer in the future.
Bothersome symptoms may indicate a more serious condition, such as colon cancer.
After you have polyps removed, your doctor will recommend that you get tested for them regularly.