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Polyps of the Colon and Rectum

By

Minhhuyen Nguyen

, MD, Fox Chase Cancer Center, Temple University

Last full review/revision Mar 2021| Content last modified Mar 2021
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A polyp is a projecting growth of tissue from the wall of a hollow space, such as the intestines.

Polyps that grow on the intestinal or rectal wall protrude into the intestine Large Intestine The large intestine consists of the Cecum and ascending (right) colon Transverse colon Descending (left) colon Sigmoid colon (which is connected to the rectum) read more or rectum Rectum and Anus The rectum is a chamber that begins at the end of the large intestine, immediately following the sigmoid colon, and ends at the anus (see also Overview of the Anus and Rectum). Ordinarily, the... read more and may be noncancerous (benign), precancerous (adenomatous), or cancerous (malignant carcinoma). Polyps vary considerably in size, and the bigger the polyp, the greater the risk that it is cancerous or likely to become cancerous (that is, they are precancerous). Polyps may grow with or without a stalk (a thin piece of tissue that joins the polyp to the intestinal wall, similar to how the neck joins the head to the body).

There are many types of polyps but doctors typically divide them into

  • Adenomatous polyps

  • Nonadenomatous polyps

Adenomatous polyps, which consist primarily of glandular cells that line the inside of the large intestine, are likely precancerous.

Nonadenomatous polyps can develop from many cell types, including the nonglandular cells that line the intestine, fat cells, and muscle cells. Some nonadenomatous polyps are caused by other disorders, for example the inflammatory polyps that develop in people with chronic ulcerative colitis. Nonadenomatous polyps are less likely to be precancerous.

Hereditary conditions that cause intestinal polyps

In Peutz-Jeghers syndrome, people have many small polyps in the stomach, small intestine, and large intestine. They also have numerous bluish black spots on their face, inside their mouth, and on their hands and feet. The spots tend to fade by puberty except for those inside the mouth. People with Peutz-Jeghers syndrome have an increased risk of developing cancer in many organs, particularly the pancreas, stomach, small intestine, colon, breast, lung, testes, ovaries, and uterus.

Examples of Peutz-Jeghers Syndrome

Symptoms of Colorectal Polyps

Most polyps do not cause symptoms. When they do, the most common symptom is bleeding from the rectum. A large polyp may cause cramps, abdominal pain, obstruction, or intussusception Intussusception Intussusception is a disorder in which one segment of the intestine slides into another, much like the parts of a telescope. The affected segments block the bowel and block blood flow. The cause... read more (one segment of the intestine slides into another, much like the parts of a telescope). Large polyps with tiny fingerlike projections that can be seen only with a microscope (called villous adenomas) may excrete water and salts, causing excessive watery diarrhea that may result in low levels of potassium in the blood (hypokalemia Hypokalemia (Low Level of Potassium in the Blood) In hypokalemia, the level of potassium in blood is too low. A low potassium level has many causes but usually results from vomiting, diarrhea, adrenal gland disorders, or use of diuretics. A... read more ). Rarely, a rectal polyp on a long stalk drops down and dangles through the anus.

Diagnosis of Colorectal Polyps

  • Colonoscopy

A doctor may be able to feel polyps by inserting a gloved finger into the rectum, but usually polyps are discovered when colonoscopy is done to examine the entire large intestine. This complete and reliable examination is done because more than one polyp is often present and any may be cancerous. During colonoscopy, any polyps seen are removed and evaluated for possible cancer.

Monitoring of Peutz-Jeghers syndrome

People who have bluish black spots on their lips or in their mouth and/or have 2 or more polyps in their digestive tract or a family history of Peutz-Jeghers syndrome should have a blood test to determine whether they have this disorder.

Once people are diagnosed with Peutz-Jeghers syndrome, doctors recommend they have regular tests to detect the various cancers that can develop with this disorder.

Prevention of Colorectal Polyps

To prevent new polyps from forming in people who have polyps or colon cancer, doctors may give aspirin and coxibs (COX-2 inhibitors).

Treatment of Colorectal Polyps

  • Removal during colonoscopy or sometimes surgery

Doctors generally recommend removing all polyps from the large intestine and rectum because of their potential to become cancerous. Polyps are removed during a colonoscopy procedure using a cutting instrument or an electrified wire loop. If a polyp cannot be removed during colonoscopy, abdominal surgery may be needed.

If a polyp is found to be cancerous, need for additional treatment depends on whether the cancer is likely to have spread. The risk of spread is determined by microscopic examination of the polyp. If the risk is low, no further treatment is necessary. If the risk is high, the affected segment of the large intestine is removed surgically, and the cut ends of the intestine are rejoined (see also treatment of colorectal cancer Treatment Family history and some dietary factors (low fiber, high fat) increase a person’s risk of colorectal cancer. Typical symptoms include bleeding during a bowel movement, fatigue, and weakness... read more Treatment ).

When a person has a polyp removed, doctors do colonoscopy to examine the entire large intestine and rectum. Follow-up colonoscopies are done at different intervals depending on many factors including the number, size, and type of the polyps. If colonoscopy cannot be done, a barium enema x-ray X-Ray Studies of the Digestive Tract X-rays often are used to evaluate digestive problems. Standard x-rays (plain x-rays) do not require any special preparation (see Plain X-Rays). These x-rays usually can show a blockage or paralysis... read more or computed tomography (CT) colonography may be done to view the large intestine.

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