Flexible sigmoidoscopy lets your doctor examine the lower part of the colon (large intestine, bowel) by passing a flexible telescope through the back passage and slowly advancing it through the rectum and into lower part of the colon. A flexible sigmoidoscopy is like a limited version of colonoscopy, when only the lower part of the bowel needs to be examined.
Your doctor will discuss what preparation is appropriate. In general, preparation consists of one or two enemas prior to the procedure but may include laxatives or dietary modifications as well. Because the rectum and lower colon must be completely empty for the procedure to be accurate, it's important to follow the instructions carefully.
Most medications can be continued as usual, but some medications can interfere with the preparation or the examination. Inform your doctor about medications you're taking, particularly blood-thinning drugs such as aspirin, clopidogrel, warfarin or heparin, arthritis medications, insulin or iron tablets. Also, be sure to mention allergies you have to medications.
Flexible sigmoidoscopy is usually well-tolerated. Sedation is not normally required. You might experience a feeling of pressure, bloating or cramping during the procedure. You will lie on your side while the doctor passes the endoscope through the rectum and colon. The lining of the bowel is examined both on the way in and as the endoscope is being withdrawn.
If an area needs further evaluation, an instrument can be passed through the endoscope to obtain a biopsy (a sample of the colon lining) for analysis. Biopsies are used to identify many conditions, and do not necessarily mean that anything sinister is suspected. Polyps may be found during flexible sigmoidoscopy, and will most likely be biopsied or removed during the examination. Polyps are abnormal growths in the colon lining that are usually benign (non-cancerous), and can vary in size from a tiny dot to several inches.
If polyps are found your doctor may recommend that you have a colonoscopy (a complete examination of the colon) to check for an remove any polyps further up the colon.
Your doctor will explain the results to you when the procedure is done, although if there are biopsies or polyps removed the results of these will not be available for a week or two. You might feel bloating or some mild cramping because of the air that was passed into the colon during the examination. This will disappear quickly when you pass gas. You should be able to eat and resume your normal activities after leaving the hospital, assuming you did not receive any sedative medication.
Although complications can occur, they are very rare when doctors who are specially trained and experienced in this procedure perform the test.
Bleeding can occur at the site of biopsy or polypectomy, but it's usually minor. Bleeding usually stops on its own, or can be controlled through the endoscope; it rarely requires follow-up treatment. A perforation, or tear, through the bowel wall that could require surgery is a rare but serious complication. Some patients can have a reaction to sedative drugs if given, or complications relating to heart or lung disease.
Although complications after flexible sigmoidoscopy are uncommon, it's important to recognize early signs of possible complications. Make contact immediately if you notice severe abdominal pain, fever and chills, or bleeding from the back passage of more than half a cup. Note that bleeding can sometimes be delayed until several days after the procedure.