What is sigmoidoscopy?

A sigmoidoscopy may be performed to check for colorectal cancer (colon cancer) or to help diagnose the source of symptoms such as unexplained weight loss, diarrhea, bleeding from the anus, or abdominal pain. Also called flexible sigmoidoscopy, the procedure involves inserting into the rectum a thin, flexible tube with a tiny light and camera (sigmoidoscope) on the end to scan the inner lining of the rectum and the sigmoid colon, which is the lower part of the large intestine. The sigmoidoscope allows the doctor to see abnormalities such as colon polyps, ulcers, inflammation and cancer.

How to prepare for sigmoidoscopy

The most important thing about preparing for a sigmoidoscopy is to clean out the bowels so that the doctor can get a clear view of colon. You will be given specific instructions on how to get ready for the procedure, which will include eating only certain fluids and broth the day before and discontinuing certain medications. You will also follow a bowel prep procedure to help eliminate everything in your body the night before. This may include a liquid laxative that you drink as well as an enema. Because the bowel prep will cause diarrhea, you’ll need to be at home or in a comfortable environment where you can access the bathroom as often as needed.

How sigmoidoscopy procedure is done

While sigmoidoscopy is not painful, it may be uncomfortable. You will be asked to lie on your side with your knees bent. There is no anesthesia involved so you will be awake and alert for the procedure. The doctor will gently insert the sigmoidoscope into the anus and up through the rectum until it reaches the transverse colon. The camera on the end of the tube will take pictures that project onto a video screen allowing the doctor to examine the lining of the colon. If there are any polyps, the doctor can also remove these during the sigmoidoscopy. These will also be sent for biopsy to determine whether or not they are cancerous. Most colon polyps are not cancerous but most colon cancer begins as a polyp so early removal is the best way to prevent disease. The doctor will slowly withdraw the sigmoidoscope and will again examine the colon on the way out.

Risks and recovery from sigmoidoscopy

You may have mild cramping and bloating immediately after the procedure. You can resume your regular eating habits and activities right away. A small amount of bleeding from the anus is normal and this light bleeding may continue up to several weeks, especially if you had polyps removed. If the bleeding continues or you have any concerns about how much blood, be sure to call your doctor right away. Other risks include:

  • Abdominal pain
  • Bloody bowel movements
  • Dizziness
  • Fever
  • Weakness

The results of your sigmoidoscopy may be available right away or within a few days. If you had a biopsy performed on sample tissue, the results may take a few days. Your doctor will discuss the results of the sigmoidoscopy with you and recommend any additional testing or treatment options.