Introduction

A sigmoidoscopy is a test that looks at the rectum and lower part of the large intestine. "Colon" is the medical term for the large intestine, and the sigmoid colon is the lower part. The sigmoid colon ends in the rectum. Your colon helps your body absorb water and nutrients from the food you eat. It’s also where your stool is formed. A sigmoidoscopy, also called a flexible sigmoidoscopy, is a procedure that lets your doctor look inside your sigmoid colon by using a flexible tube with a light on it. It helps your doctor check for ulcers, abnormal cells, polyps and cancer.

Sigmoidoscopy is typically conducted for diagnostic and screening purposes. Some common conditions and situations in which sigmoidoscopy may be performed include:

1. Screening for colorectal cancer: Sigmoidoscopy can be used as a screening tool to detect precancerous growths (polyps) or early signs of colorectal cancer. It is often recommended as part of routine colorectal cancer screening, particularly in individuals over the age of 50.
2. Evaluation of rectal bleeding: If a person experiences rectal bleeding, sigmoidoscopy can help determine the cause. It allows the doctor to visualize the rectum and lower part of the colon to identify any abnormalities, such as hemorrhoids, inflammation, or polyps.
3. Investigation of abdominal pain: Sigmoidoscopy may be performed to investigate the cause of unexplained abdominal pain or discomfort localized in the lower part of the abdomen.
4. Monitoring inflammatory bowel disease (IBD): Sigmoidoscopy is used to evaluate the extent and severity of inflammation in individuals with chronic conditions like ulcerative colitis or Crohn's disease. It helps assess disease activity and guide treatment decisions.
5. Follow-up after a positive fecal occult blood test (FOBT): FOBT is a non-invasive test used to detect hidden blood in the stool, which can indicate the presence of colorectal polyps or cancer. If the FOBT result is positive, sigmoidoscopy may be recommended to further investigate the source of bleeding.
6. Removal of polyps: During sigmoidoscopy, if polyps or abnormal tissue are identified, they can be removed or biopsied for further examination. This allows for both diagnosis and treatment.

It's important to note that sigmoidoscopy only visualizes the lower part of the colon, whereas a colonoscopy examines the entire colon. Depending on the specific circumstances, a doctor may recommend a sigmoidoscopy or a colonoscopy based on the individual's symptoms, medical history, and the desired extent of examination.

Preparing for a sigmoidoscopy:

Preparing for a sigmoidoscopy is similar to preparing for a colonoscopy. If your entire colon needs to be empty, preparation becomes even more like what you need to do for a colonoscopy. For example, you’ll follow a clear liquid diet for one to three days before the procedure. You may be given a powder laxative to mix with fluid to help empty your intestines. Liquids you can consume include plain coffee or tea, water, fat-free broth, gelatin, like Jell-O or sports drinks with electrolytes. 

Before the procedure, tell your doctor about any medical conditions you have and all medications and supplements you’re taking.

Procedure:

Before the procedure, your doctor will have you lie on your left side on an examination table. They’ll insert a thin, flexible tube called a sigmoidoscope into your anus. The tube has a light and a very small camera on the end so images can be transmitted onto a monitor for your doctor to see. The tube also inflates your colon with some air to make it easier to examine. You might be uncomfortable, but the procedure isn’t typically painful. People aren’t usually under sedation during a sigmoidoscopy, so your doctor might ask you to shift every so often to make it easier to move the scope.

If your doctor sees any polyps or growths, they might remove them. If there are any abnormal areas in your colon, small pieces of tissue might be removed for further examination. If your doctor takes a tissue sample, bleeding could occur in the place where the sample was taken. The entire procedure takes 10 to 20 minutes. People can usually drive themselves to and from the appointment. If you’ve been given medication to calm or sedate you, you’ll need someone to drive you home afterwards.

 After the procedure:

You can expect to go back to normal activities immediately. This includes driving unless the doctor gave you medicine to help you relax. If so, you will be sleepy after the test. You may want to arrange ahead of time for a friend or family member to drive you home. You might have cramps or feel bloated at first. This usually goes away in a few hours. You might pass gas and even have some diarrhoea as you release the air that the doctor put into your colon.

You might notice a small amount of bleeding from your rectum. This is normal. However, call your doctor if you continue bleeding or if you have blood clots. Also, call if you have:

• Abdominal pain (belly pain)
• Dizziness
• Weakness
• bloody stool
• Fever of 100 F (37.8 C)