What’s the Difference Between an Endoscopy, Colonoscopy and Sigmoidoscopy?

The short answer from a colorectal surgeon
Doctor holding endoscope

Q: What is an endoscopy, and how is it different from a colonoscopy and sigmoidoscopy?

A: Endoscopy is just a general term meaning we’re going to use a scope through one of your orifices to look at something inside of you.

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Sigmoidoscopy and colonoscopy, and even esophagogastroduodenoscopy (EGD), are fancy words for different kinds of endoscopy. The –oscopy ending means you’re using a scope to look at something. And then the prefix of the word is what you’re looking.

So colonoscopy is a longer scope, and it can look all the way around the colon, which is about 6 feet long. In many cases, we can get through the little valve that connects your small bowel to your large bowel, down by your appendix, and also get a sneak preview at the very end of your small bowel. We do this to evaluate symptoms and to check for polyps or cancer.

A flexible sigmoidoscopy is essentially a shorter scope that we use to look at the lower part of your colon – so your anus, your rectum, your sigmoid colon and your descending colon. That’s about 70 cm. And occasionally, in certain people you can even get up to the transverse colon.

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A proctoscopy or anoscopy (procedures to examine the inside of the rectum and anus), and even a flexible sigmoidoscopy, are less invasive and can be done in an office. But with colonoscopy, in general, you need to have a full bowel prep and some sedation.

— Colorectal surgeon Scott Steele, MD

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