Polyps are noncancerous tumors involving the lining of bowel, most commonly the colon. They can be flat or grow on a stalk protruding into the lumen. They can vary in size from diminutive to several centimeters in size.
Major risk factors for developing polyps are age older than 50 years, personal and/or family history of colon polyps and/or colon cancer and some rare familial polyp or cancer syndromes.
Most polyps do not cause symptoms. Large polyps can cause blood in stool. Therefore the best way to detect polyps is by screening an individual with no symptoms. Several screening techniques are available: Testing stool specimen for traces of blood, sigmoidoscopy to look into left (lower one third) colon and radiological tests like Barium enema and CT colonography. If one of these tests suspects or finds polyps, colonoscopy is recommended to remove them.
Many experts recommend colonoscopy as a screening method for colon cancer. An advantage of colonoscopy over other screening techniques is that polyps in the entire colon can be removed during the same procedure.
Two common types of polyps are hyperplastic and adenomatous polyps (adenoma). Adenomas are considered to be the precursors for majority of colon cancers although most adenomas never become cancers. Some polyps contain small areas of cancer. Polyps cannot be differentiated into hyperplastic polyps or adenomas by the appearance. Removing all polyps found during colonoscopy is recommended. Histological (microscopic) examination of polyps differentiates between hyperplastic polyps and adenomas. Large polyps are more likely to become cancerous.
Most polyps can be removed during colonoscopy by biopsy forceps, or with wire loop (snare) with/without burning the base of polyp with electric current. A pathologist then examines the resected polyps under microscope. If a large or unusual looking polyp is removed or left for possible surgical resection, the site is marked by injecting a small amount of sterile India ink into the bowel wall. This is called endoscopic tattooing.
Possible complications (which are uncommon) of polyp resection include 1) bleeding from polypectomy site which can be immediate or delayed. Persistent bleeding is mostly controlled by treatment with repeat colonoscopy and 2) perforation of colon that may require surgical repair.
Timing of next colonoscopy depends on several factors including the number, size and the tissue type of removed polyps, personal and family history of colon polyps and colon cancer and the quality of the colon cleansing at previous procedure.