Sigmoidoscopy: Purpose, Preparation, Procedure and Risk


A sigmoidoscopy, also called a flexible sigmoidoscopy, is a procedure in which a doctor look inside your sigmoid colon by using a flexible tube with a light on it.

August 30, 2018

A sigmoidoscopy, also called a flexible sigmoidoscopy, is a procedure in which a doctor look inside your sigmoid colon by using a flexible tube with a light on it. It helps the doctor check for ulcers, abnormal cells, polyps and cancer. Typically, pieces of tissue will be taken as samples to check for any abnormal cell changes. Your colon helps your body absorb water and nutrients from the food you eat and form the stool. The last third of your descending colon is called the sigmoid colon. It is connected to your anus by your rectum.
A colonoscopy helps doctors examine the entire colon. But sometimes a close inspection is required which can be done using a sigmoidoscopy. In this procedure a flexible tube connected to a fiberoptic camera is used. A light is transmitted through the scope to the tip by a bundle of light fibers and this light is used by your doctor to look at your intestine through an eyepiece or video screen.
Sigmoidoscopy is used to look inside your rectum and the lower part of your colon, including the sigmoid and descending colon.

Purpose of Sigmoidoscopy:

A flexible sigmoidoscopy can help a doctor find the cause of unexplained symptoms, such as

  • bleeding from your anus
  • changes in your bowel activity such as diarrhea
  • pain in your abdomen
  • unexplained weight loss

It is used as a screening tool for colon polyps and colon and rectal cancer. Screening may find diseases at an early stage which helps in determining the treatment. There is a a better chance of curing the disease if it is diagnosed in early stage. Even though the sigmoidoscopy is the most important technique in the evaluation of colon cancer, a very small percentage of people with normal sigmoidoscopy findings may later be found to have colon cancer. A diagnosis of your particular disease is made for which you may need additional testing, consultation, therapy, or follow-up. Screening for colon and rectal cancer are advisable at the age of 50 if you don't have health problems or other factors that make you more likely to develop colon cancer.
Factors that make you more likely to develop colorectal cancer include:

  • Family history of someone in your family has had polyps or cancer of the colon or rectum
  • Personal history of inflammatory bowel disease, such as ulcerative colitis or Crohn's disease
  • Other factors, such as if you weigh too much or smoke cigarettes

Screening is recommended at a younger age if you have these risk factors, and you may need to be tested more often. Colonoscopy is recommended to screen for colon cancer as it shows the entire colon and can remove colon polyps. However, preparing for and performing a flexible sigmoidoscopy may take less time and you may not need anesthesia. If any abnormal tissue or one or more polyps are found during a sigmoidoscopy, you should have a colonoscopy to examine the rest of your colon.

Preparation for a Sigmoidoscopy:

Preparing for a sigmoidoscopy is similar to preparing for a colonoscopy. You will likely use one or more enemas approximately two hours before the procedure. You will need to follow a clear liquid diet for one to three days before the procedure to empty your entire colon. A strong laxative called a bowel cleanser can be used to clear your bowel of fecal contents before sigmoidoscopy. polyethylene glycol 3350, magnesium citrate, Citroma, and senna are some of the examples of laxative. These medications can cause diarrhea, which can be uncomfortable, but unless the bowel is empty of stool, it can prevent your doctor from clearly seeing the lining of your intestine. The test can be limited and may need to be repeated at a later date. You may need to follow a clear liquid diet the day before the procedure. In most cases, you may drink or eat the following:

  • fat-free bouillon or broth
  • gelatin in flavors such as lemon, lime, or orange
  • plain coffee or tea, without cream or milk
  • sports drinks in flavors such as lemon, lime, or orange
  • strained fruit juice, such as apple or white grape. Avoiding orange juice and red or purple liquids is recommended because it can look like blood in the colon.
  • water

You should talk with your doctor about any medical conditions you have and all prescribed and over-the-counter medicines, vitamins, and supplements you take, including:

  • arthritis medicines
  • aspirin or medicines that contain aspirin
  • blood thinners
  • diabetes medicines
  • nonsteroidal anti-inflammatory drugs, such as ibuprofen or naproxen
  • vitamins that contain iron or iron supplements

Procedure for a Sigmoidoscopy:

Sigmoidoscopy is performed by a doctor during an office visit or at a hospital or an outpatient center. You typically do not need sedatives or anesthesia, and the procedure takes about 20 minutes. You will have to lie down on your left side with your knees bent and pulled up slightly toward your head during the procedure.
The doctor will examine your rectum first with a finger lubricated with special jelly. The tip of the scope is then lubricated with the same jelly and slowly inserted into your rectum. The doctor will slowly advance the tube through your lower intestine.
The scope pumps air into your large intestine to give the doctor a better view. The camera sends a video image of your intestinal lining to a monitor, allowing the doctor to examine the tissues lining your sigmoid colon and rectum. You will be asked to move several times on the table to adjust the scope for better viewing. Once the scope has reached your transverse colon, the doctor slowly withdraws it and examines the lining of your sigmoid colon again.
Your doctor may remove polyps if it is found during the procedure and send them to a lab for testing. Colon polyps are common in adults and are harmless in most cases. However, most colon cancer begins as a polyp, so removing polyps early is an effective way to prevent cancer. If the doctor encounters a suspicious area of intestine, he or she may remove a small piece of the tissue for analysis. This is done with the same scope and is known as a biopsy.
Your doctor may suggest a colonoscopy if polyps or other abnormal tissue are found during a sigmoidoscopy. You can resume regular activities right away after the procedure and can return to a normal diet.
You may experience mild abdominal cramping and gas as a result of the air that was placed in your intestine after the procedure. Some people may have slight rectal bleeding due to minor irritation and trauma from the insertion of the sigmoidoscope.

Risks of a Sigmoidoscopy:

Bleeding and perforation of the colon are the most common complications from flexible sigmoidoscopy. Most cases of bleeding occur in patients who have polyps removed. The doctor can treat bleeding that occurs during the sigmoidoscopy right away. However, you may have delayed bleeding up to two weeks after the procedure. The doctor diagnoses and treats delayed bleeding with a colonoscopy or repeat sigmoidoscopy. Perforation can be treated with surgery. The procedure can also be fatal, although this risk is rare.
If there is a positive result from biopsy, that requires further testing. You may need to repeat the procedure. You may also need to repeat it if your doctor wasn't able to get a good picture of your colon and rectum.
Seek immediate medical care if you experience severe abdominal pain, nausea, vomiting, or heavy bleeding after a sigmoidoscopy.