Sigmoidoscopy Health Article

Definition

Sigmoidoscopy is a diagnostic and screening procedure in which a rigid or flexible tube with a camera on the end (a sigmoidoscope) is inserted into the anus to examine the rectum and lower colon (bowel) for bowel disease, cancer, precancerous conditions, or causes of bleeding and pain.

Purpose

Sigmoidoscopy is used most often in screening for colorectal cancer or to determine the cause of rectal bleeding. It is also used in diagnosis of inflammatory bowel disease, microscopic and ulcerative colitis, and Crohn's disease.

Cancer of the rectum and colon is the second most common cancer in the United States. About 155,000 cases are diagnosed annually. About 55,000–60,000 Americans die each year of colorectal cancer.

A number of studies have suggested, and it is now recommended by cancer authorities that people over 50 be screened for colorectal cancer using endoscopy every three to five years. Individuals with inflammatory bowel disease, such as Crohn's disease or ulcerative colitis, who are at increased risk for colorectal cancer, may begin their screenings at a younger age, depending on when their disease was diagnosed. Many physicians screen such patients more often than every three to five years. Screening should also be done in patients who have a family history of colon or rectal cancer or small growths in the colon (polyps).

Some physicians do this screening with a colono-scope, which allows them to see the entire colon. However, most physicians prefer sigmoidoscopy, which is less time consuming, less uncomfortable, and less costly.

Studies have shown that one quarter to one-third of all precancerous or small cancerous growths can be seen with a sigmoidoscope. About one-half are found with a 1 ft (30 cm) scope, and two-thirds to three-quarters can be seen using a 2 ft (60 cm) scope.

In some cases, the sigmoidoscope can be used therapeutically in conjunction with other equipment, such as electrosurgical devices, to remove polyps and other lesions found during the sigmoidoscopy.