Sigmoidoscopy is a procedure where a doctor or nurse looks into the rectum and sigmoid colon using an instrument called a sigmoidoscope.

What is a sigmoidoscopy?

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. A doctor or nurse inserts the sigmoidoscope into the anus and pushes it slowly into the rectum and sigmoid colon. This allows the doctor or nurse to see the lining of the rectum and sigmoid colon. The procedure is not painful but it may be a little uncomfortable.

Bowel preparation

For a doctor or nurse to get a clear view, your rectum and lower bowel need to be empty of faeces (stools or motions). You should be given detailed instructions on how to clear your bowel before you have a sigmoidoscopy. This is usually by taking powerful laxatives for a day or two, or by using one or two enemas prior to the procedure. A commonly used laxative to clear the bowel is called Picolax. A common plan is:

• For three days before the procedure - eat a light diet.
• On the day before the procedure - take one Picolax sachet (by mouth) at 8am and one at 6 pm. Read the instructions carefully on the Picolax sachet on how much water to add.
• For 12 hours before the procedure - have fluids only (no solids in your diet), but you can eat a normal light breakfast on the morning just before the procedure.
• Sometimes you will be given an enema on arrival in the hospital to clear the very bottom of the bowel of faeces.

The test itself

This test takes 15-20 minutes. Usually you do not need an anaesthetic or sedation. You wear a hospital gown so that the lower half of your body is exposed. You will be asked to lie on your left side with your knees drawn up toward your chest.

First the doctor or nurse will gently insert a gloved and lubricated finger (or fingers) into the rectum to check for blockage 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 an urge to defecate ('move your bowels'). As the sigmoidoscope is slowly removed, the lining of the bowel is carefully examined.

A small sample (biopsy) of bowel lining may be taken during the procedure. (A channel in the sigmoidoscope allows the doctor or nurse to pass forceps or other instruments to take biopsies, or for therapy.) The sample is sent to the laboratory to be looked at under the microscope. It may also be tested for various conditions that can affect the bowel.

© EMIS and PIP 2006   Updated: February 2006

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