Sigmoidoscopy is an examination used to look inside the lower part of the bowel. The sigmoid colon is the final portion of the bowel that is joined to the rectum.
A sigmoidoscope is a small tube, with an attached light source, about the thickness of your finger. Your consultant inserts the sigmoidoscope into the anus and pushes it slowly into the rectum and sigmoid colon. This allows the doctor to see the lining of the rectum and sigmoid colon. The procedure is not usually painful but it may be a little uncomfortable.
There are two types of sigmoidoscope which may be used. The most commonly used is the flexible sigmoidoscope. This instrument allows views around bends in the colon. A flexible sigmoidoscope provides a better view of the lower colon and usually makes the examination more comfortable.
The rigid sigmoidoscope allows your doctor to look into the rectum and the bottom part of the colon but it does not reach as far into the colon as the flexible sigmoidoscope.
Sigmoidoscopy is usually recommended to investigate the cause of bleeding or pain from the back passage. The test can also look for evidence of cancer or inflammation of the rectum and lower colon. Sigmoidoscopy can also be used to remove polyps and take samples of tissue for analysis. This is performed by passing a thin grabbing instrument down a side channel of the sigmoidoscope.
This investigation takes approximately 5-10 minutes. You do not usually need an anaesthetic or sedation. Prior to the procedure an enema or suppository is used to soften the stools, which need to be evacuated from the lower part of the intestine.
You will be asked to wear a hospital gown so that the lower half of your body is exposed and need to lie on your left side with your knees drawn up toward your chest. This makes it easier for your consultant to perform the examination through the rectum.
Your consultant will gently insert gloved and lubricated fingers into the rectum to check for blockages and to widen the anus. Then the sigmoidoscope will be inserted and gently pushed further into the rectum and colon. Air is gently pumped through the sigmoidoscope to help viewing. This can cause you to feel bloated and uncomfortable and give you the urge to defecate. As the sigmoidoscope is slowly removed, the lining of the bowel is carefully examined. A small sample of bowel lining may be taken during the procedure, in the form of a biopsy.
Most sigmoidoscopies are performed without any problem. Some people may experience cramp-like pains and excess wind after the procedure. You may notice the leakage of liquid accompanied by gas for up to 24 hours. After the examination the patient can go home right away.
Sometimes a light sedative is given to help the patient relax during the procedure, and if so then they will need to be driven home by someone else. Following sedation, avoid driving or operating machinery and drinking alcohol for 24 hours.
If you experience severe abdominal pain, bloody bowel movements or rectal bleeding, or have a raised temperature within 48 hours of the procedure, please contact the hospital immediately.