Sigmoidoscopy vs. Colonoscopy: What to Know

Published April 12, 2023 by

What’s the difference between a sigmoidoscopy and colonoscopy? The most important thing to know is that both of these are valuable screening tools doctors use to find colorectal cancer. Let’s look at how they are used, when they are used, and exactly what they entail.

Doctor holding colonoscopy tool.


You may be more knowledgeable about a colonoscopy. This procedure is to screen for cancer in the entire colon. It is recommended that those with normal risk factors begin these at age 45 and then every 10 years unless there are issues. If you have more serious risk factors, your doctor may suggest you begin to have them before you are 45.

A colonoscopy’s purpose is to locate and remove any polyps and have them analyzed for cancer. With regular screenings, a polyp can be removed and if precancerous, you can be treated in a timely manner.

Prepping for a colonoscopy is probably the worst part. Your colon must be empty so you cannot have solid food the day before and must ingest a fluid to clear your colon.

You are given a sedative prior to the procedure and you may be partially awake, but you will feel nothing. A long tube with a camera and light is inserted into your rectum. The pictures from the camera are shown in real time on a computer screen so the doctor is able to visualize the inside of your colon. GI Solutions of Illinois will remove any polyps with tiny instruments.


A sigmoidoscopy is a tool which looks at the lower part of your colon, including the rectum and anus. This is less invasive than a colonoscopy and one type can be done right in the office setting.

There are two types:

  • A rigid sigmoidoscopy uses a proctoscope or sigmoidscope which is a plastic or metal device inserted into the anus. Air is directed to slightly enlarge the area and GI Solutions of Illinois can shine a light inside. This can be accomplished right in the office for a quick evaluation. Tissue samples can be taken.
  • The second type is known as a flexible sigmoidoscopy. Here, a bendable tube is inserted into the rectum to find and possibly evaluate polyps, ulcers, or hemorrhoids. Since this can help identify possible issues in the lower part of the colon, patients are recommended to have a flexible one done between colonoscopies.

Deciding on Which Tool to Use

If there are sudden symptoms like bleeding, pain, bouts of constipation or diarrhea, a colonoscopy would most likely be recommended.

The best course to protect your colorectal health is to alternate these two screening tools as your doctor directs.

Contact GI Solutions of Illinois at (773) 631-2728 if you are experiencing symptoms or if it’s time to schedule your colonoscopy in Chicago, IL.


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