Flexible sigmoidoscopy is a procedure that is similar to a colonoscopy. However, it only examines the last third of the colon and rectum, whereas the colonoscopy examines the entire colon. It can be used in patients having minor symptoms or as a screening for cancer. In some cases, it might need to be followed up with a colonoscopy.
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. They also use it to look for early signs of cancer in the descending colon and rectum. With flexible sigmoidoscopy, the physician can see:
- Abnormal growths
- Ulcers in the descending colon and rectum.
Flexible sigmoidoscopy is not sufficient to detect polyps or cancer in the ascending or transverse colon (two-thirds of the colon).
For the procedure, you will lie on your left 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 (called a biopsy) to the lab for testing.
Flexible sigmoidoscopy takes 10 to 20 minutes. During the procedure, you might feel pressure and slight cramping in your lower abdomen. These feelings should go away after the procedure is finished.