Flexible Sigmoidoscopy

Flexible sigmoidoscopy enables the physician to look at the inside of the large intestine from the rectum through the last part of the colon, called the sigmoid or descending colon. Physicians may use the procedure to find the cause of diarrhea, abdominal pain or constipation. (Read about "Digestive System" "Diarrhea" "Constipation") They also use it to look for early signs of cancer in the descending colon and rectum. (Read about "Colorectal Cancer") With flexible sigmoidoscopy, the physician can see bleeding (Read about "Gastrointestinal Bleeding"), inflammation, abnormal growths and ulcers in the descending colon and rectum. The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) says flexible sigmoidoscopy is not sufficient to detect polyps (Read about "Colon Polyps") or cancer in the ascending or transverse colon. They are the other two-thirds of the colon. For that, a colonoscopy is needed. (Read about "Colonoscopy")

The colon and rectum must be completely empty for flexible sigmoidoscopy to be thorough and safe, so the physician will probably tell you to drink only clear liquids for 12 to 24 hours beforehand. A clear liquid diet includes the following:

• fat-free bouillon or broth
• gelatin, not red or purple
• strained fruit juice, no purple or red grape juice
• water
• plain coffee
• plain tea
• diet soda

You may be instructed to take laxatives the day before the procedure. The night before or right before the procedure, you may also be given an enema. Your physician may give you other special instructions.

For the procedure, you will lie on your side on the examining table. The physician will insert a short, flexible, lighted tube into your rectum and slowly guide it into your colon. The tube is called a sigmoidoscope. The scope transmits an image of the inside of the rectum and colon, so the physician can carefully examine the lining of these organs. The scope also blows air into these organs, which inflates them and helps the physician see better.

If anything unusual is in your rectum or colon, like a polyp or inflamed tissue, the physician can remove a piece of it using instruments inserted into the scope. The physician will send that piece of tissue (biopsy) to the lab for testing. (Read about "Biopsy" "Laboratory Testing")

Bleeding and puncture of the colon are possible complications of sigmoidoscopy, according to NIDDK. However, such complications are uncommon.

Flexible sigmoidoscopy takes 10 to 20 minutes. During the procedure, you might feel pressure and slight cramping in your lower abdomen. You will feel better afterward when the air leaves your colon.