Sigmoidoscopy is a less invasive alternative to the traditional colonoscopy procedure. It is performed by gastroenterologists, proctologists and other medical doctors as a routine test to screen for colon cancer for monitoring for healing in patients with IBD. Although the sigmoidoscopy procedure is very similar to colonoscopy, sigmoidoscopy is a limited colorectal examination, allowing only the lower third of the colon to be viewed, as opposed to the entire large intestine. This lower third section of the colon is called the sigmoid colon.
There are generally two kinds of sigmoidoscopy: flexible sigmoidoscopy and rigid sigmoidoscopy—although the former is much more common and the preferred procedure among patients and medical providers. Flexible sigmoidoscopy involves a device called a sigmoidoscope, which can be inserted through the patient’s rectum, bent in several ways and guided through the colon, while rigid sigmoidoscopy involves a more rigid device. Both devices have a light and a small camera attached to their ends, which allows the practicing doctor to see inside the sigmoid colon and search for signs of colon cancer without resorting to open surgery.
Patients who are trying to avoid traditional colonoscopy but who need to be screened for colon cancer with a sigmoidoscopy may display any combination of the following symptoms: diarrhea, constipation, rectal bleeding or stomach pain. During colonoscopy or any other screening test, the goal of the gastroenterologist (GI doctor) is to detect the source of these symptoms, whether it is colon polyps or inflammation of the bowel tissue. If a patient has any abnormal growth or inflammation near the rectal area or within the sigmoid colon, a diagnosis can usually be made after a sigmoidoscopy. If abnormalities are found in these areas, it is very likely that a traditional colonoscopy will be ordered to check for signs of colon cancer higher up the gastrointestinal (GI) tract.
Flexible Sigmoidoscopy Procedure
During the procedure, patients will be asked to lie on their left side on the examination table while a doctor inserts a sigmoidoscope into their rectum. The sigmoidoscope is small, short and flexible. It is tubular in shape and has a light on the end to give the doctor better viewing capabilities. The sigmoidoscope can also allow the doctor to pump air through the lower part of the colon, inflating it so that the doctor can more closely examine the colorectal tissue.
Biopsies and polyp removal procedures can be performed during a sigmoidoscopy, in the case that abnormalities are detected. This process is done by using a small cutting tool that can be inserted through the sigmoidoscope.
The entire sigmoidoscopy procedure will take between 10 and 20 minutes. It is a much quicker procedure than traditional colonoscopy, which can take up to an hour to complete. Patients are sometimes sedated to ease discomfort of sigmoidoscopy, but generally, sedation is optional. While patients may feel pressure and cramping in the stomach area while the sigmoidoscope is inserted, any discomfort usually goes away quickly once the device is removed and air leaves the colon.
Despite the procedure being minimally invasive, sigmoidoscopies require the same process of bowel prep required before a colonoscopy. The entire colon must be completely emptied by way of laxatives and an all-liquid diet during the day before a sigmoidoscopy. The reason this is that any residual fecal matter left inside the colon can obstruct the doctor’s view of the bowel tissue, as well as be mistaken for a tumor, polyp or other abnormal growth. Sometimes a tap water enema is used before the procedure starts, to promote further colon cleansing.
If you would like to screen for colon cancer with sigmoidoscopy, please contact one of the colonoscopy specialists listed in our directory for help with getting started.
Reviewed 12/12/2011 by David M. Nolan, M.D.
Diplomate of the American Board of Internal Medicine, 2011
Currently a Fellow of Gastroenterology, at UCI 2011-2014