Colon polyps are small growths of tissue that project from the lining of a section of the large intestine known as the colon. Colon polyps typically grow in two shapes: flat or with a stalk. There are many different types of polyps, with some more likely to result in complications than others.

Colorectal polyps, or bowel polyps, become increasingly common as people age. Estimates suggest that they occur in at least 30% of adults aged 50 years or older in the United States. However, they still may affect roughly 6–12% of children.

Many colon polyps are harmless, but some may develop into cancer. Certain types of colon polyps are more likely to become cancerous. If they do, it can take many years for them to result in colon cancer.

In this article, we discuss the different shapes and types of colon polyps, potential treatment options, and when to contact a doctor.

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Colon polyps are growths that project from the inner lining of the colon or rectum. A person may have only one polyp or several ones spread throughout the colon or rectum. Polyps can vary in size, ranging from a couple of millimeters to several centimeters.

Polyps are fairly common. In the U.S., 15–40% of adults have polyps. Also, polyps are more common in men and older adults.

Most polyps are noncancerous, or benign. However, some polyps can develop to become malignant, or cancerous. For this reason, a surgeon may remove them when detected.

Polyps often cause no symptoms. In many cases, a doctor only identifies polyps during a medical exam or colonoscopy.

However, in rare cases, polyps may cause:

Polyps can form in different shapes. People may refer to these shapes as flat, or sessile, or with a stalk, also known as pedunculated.

Some polyps grow flat and project outward from a broad base. Others can be depressed, or project inward into the colon or rectum lining. Doctors refer to these as sessile polyps.

Pedunculated polyps, on the other hand, may appear raised, projecting out into the hollow center of the colon or rectum. They may grow in the shape of a small cauliflower or mushroom suspended from a stalk or base.

There are several types of colon polyps that a doctor can see using a microscope. Some examples include:

Tubular adenomas

Adenomas typically have three growth patterns: tubular, villous, and tubulovillous.

Tubular are the most common type of colon polyps. They usually account for 80% of all adenomatous polyps. Tubular adenomas are typically small pedunculated polyps, less than half an inch in size. They usually have a tube-like or rounded shape.

Tubular adenomas generally take years to form. Typically, the larger the polyp, the greater the risk it may become cancerous.

Villous adenomas

Villous adenomas are generally larger pedunculated polyps and grow in a cauliflower-like shape. The term “villous features” refers to the finger-like or leaf-like projections.

Villous adenomas are more likely to become cancerous. They account for 5–15% of all adenomatous polyps.

Tubulovillous adenomas

Some polyps, called tubulovillous, contain a mixture of tubular and villous growth. They usually have 25–75% villous features, and they account for roughly 5–15% of all adenomatous polyps.

Serrated adenomas

These polyps contain tissues with a sawtooth look. There are two types: sessile serrated adenomas and traditional serrated adenomas.

Most serrated adenomas are sessile and resemble small raised bumps.

Sessile serrated polyps tend to carry a low risk of becoming cancerous as long as they do not contain major cellular changes. Traditional, or non-sessile, serrated adenomas are rarer and typically pedunculated. They carry a high risk of becoming cancerous.

Hyperplastic

These types of colon polyps are typically benign, and they are not usually a cause for concern. They will rarely become cancerous, as they have a low malignancy potential.

Inflammatory

These types of polyps occur most often in people with inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis. Some people may also refer to these as pseudopolyps, as they are not true polyps but a reaction to inflammation in the colon.

Inflammatory polyps are usually benign and generally do not carry the risk of developing into colon cancer.

Hamartomatous

These types of colon polyps are generally noncancerous. Some people may also refer to them as juvenile polyps. They are more likely to develop in children.

Complex polyps are polyps that are either very difficult or unsafe to remove using regular techniques. Some people may also refer to these as defiant or difficult polyps.

In most cases, doctors may remove complex polyps using endoscopic mucosal resection, endoscopic submucosal dissection, surgery, or a combination of these methods.

In most cases, a surgeon will remove polyps to reduce the risk of cancer.

Surgeons can normally remove polyps during a colonoscopy in a process called polypectomy. During a colon polypectomy, a surgeon inserts a long, thin, flexible tube with a camera and light on the end through the rectum to look inside the colon and locate the polyp.

Surgeons can use different techniques to remove polyps. Some options include cold forceps polypectomy, hot forceps polypectomy, and snare polypectomy.

Once a surgeon removes the polyp, they may send it to a pathologist. This is a doctor that specializes in finding the origin of diseases. They will examine the polyp using a microscope to determine the type of polyp and whether it is or can become cancerous.

If a person has a history of polyps, they are likely to develop more in the future. This may increase their risk of developing cancerous polyps. Therefore, after a person has polyps removed, a doctor may monitor them more closely and test them more frequently.

Typically, colon polyps are harmless and not a cause for concern. However, people should speak with a healthcare professional if they experience any of the following symptoms:

  • unexplained changes in bowel habits, such as constipation or diarrhea, that last more than a few days
  • blood appearing on toilet paper, on underwear, or in stool
  • nausea, vomiting, and fever
  • unexplained exhaustion and bruising easily

People should also consult a doctor if any of the following symptoms occur following the removal of polyps:

Colon, rectal, or bowel polyps are fairly common and typically harmless. However, certain types, such as adenomatous polyps, can become cancerous and will likely require removal.

People should speak with a doctor if chronic bowel habit changes occur or if blood appears in the stool, on toilet paper, or on underwear. Most healthy people without colon polyp risk factors should start receiving routine testing for colorectal cancer at the age of 50.