This tests allows the doctor to look inside the rectum and the lower part of the large bowel with a camera as indicated in the diagram (purple section of bowel). About 60% of bowel cancers and polyps are found in this part of the bowel.
To have a sigmoidoscopy only the left side of the colon (see purple section) needs to be clean. This is achieved by giving the patient an enema at the hospital just before the test.
The examination is usually performed without sedation and should be comfortable enough to tolerate. In some cases sedation will be planned for in advance. Where sedation is given you will not be able to drive for the next 24 hours.
If a polyp or a cancer is found biopsies are taken but it is vital then that the whole colon is examined so a colonoscopy will be arranged.
The whole procedure takes about 15 minutes. You should be able to go home as soon as the test is over. Some people have a small amount of bleeding from the back passage after sigmoidoscopy. This is normal and usually clears up on its own over a few days.