What is this condition?

Rectal polyps are masses of tissue that erupt through the mucous membrane of the colon and rectum and protrude into the digestive tract. Types of polyps include common polypoid adenomas, villous adenomas, hereditary polyposis, focal polypoid hyperplasia, and juvenile polyps (hamartomas). Most rectal polyps are benign. However, villous and hereditary polyps are likely to become malignant.

What causes it?

Formation of polyps results from unrestrained cell growth in the upper layer of the intestinal wall. Predisposing factors include heredity, age, infection, and diet. Men over age 55 are the most likely to develop villous adenomas. Women between ages 45 and 60 develop common polypoid adenomas. The incidence of rectal polyps rises in both sexes after age 70. Juvenile polyps occur most frequently among children under age 10.

What are its symptoms?

Because rectal polyps don't generally cause symptoms, they're usually discovered incidentally during a digital exam or a colonoscopic exam. Rectal bleeding is a common sign, and can vary according to the lesion's location in the colon or rectum. High rectal polyps leave a streak of blood on stools. Low rectal polyps bleed more freely. Villous adenomas may grow large and cause painful bowel movements, bur, because they are soft, they rarely cause an obstruction. Hereditary polyposis can cause diarrhea, bloody stools, and secondary anemia. In people with this type, a change in bowel habits with abdominal pain usually signals rectosigmoid cancer.

Juvenile polyps are large, inflammatory lesions, often without an epithelial covering, and focal polypoid hyperplasia produces small grainy growths.

How is it diagnosed?

To get a firm diagnosis of rectal polyps, the doctor will identify them by looking through a colonoscope or similar instrument and by analyzing a biopsy specimen. A barium enema test can help identify polyps that are located high in the colon. Supportive lab findings include traces of blood in the stools, blood studies showing low hemoglobin and hematocrit (with anemia) and, possibly, electrolyte imbalances in people with villous adenomas.

How is it treated?

Treatment varies according to the type and size of the polyps and their location in the colon or rectum. Common polypoid adenomas less than 1/2 inch (1 centimeter) in diameter require removal, frequently by fulguration (destruction by high-frequency electricity). For common polypoid adenomas over 1½ inches (4 centimeters) in diameter and all invasive villous adenomas, the surgeon will remove part of the intestine.

Focal polypoid hyperplasia can be removed by biopsy. Depending on digestive tract involvement, hereditary polyps require total removal of the affected section. Juvenile polyps are prone to shearing off on their own. If that doesn't happen, removal with a snare during colonoscopy is the treatment of choice.