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Reviewed/Revised May 2022 | Modified Sep 2022
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What is an endoscope?

Endoscope is an instrument doctors use to look inside your body. Endoscopes can also be used to do tests and treat diseases.

Endoscopes are tubes that have a light and a small video camera on the end. The scopes are hollow. Doctors can thread instruments through them to do tests and treat problems.

Endoscopes can be:

  • Rigid, made of metal that doesn't bend

  • Flexible, so they can bend around corners like a snake

Different sizes of endoscopes are used for different parts of the body. The size your doctor uses depends on what part of your body needs to be examined and treated. For example, they can be:

What is endoscopy?

Endoscopy is really any test in which doctors use a viewing tube to get a close-up view of the inside of your body. However, most of the time when doctors say "endoscopy," they mean looking in your digestive tract (gastrointestinal or GI tract) with a flexible endoscope.

Doctors do two main types of GI endoscopy:

  • Upper endoscopy—a tube goes into your mouth and down your esophagus, to look at your esophagus, stomach, and part of your small intestine

  • Lower endoscopy (colonoscopy)—a tube goes into your anus to look at your rectum and large intestine

Sigmoidoscopy is a type of lower GI endoscopy in which the doctor uses a short tube and looks at only the lower portion of your large intestine.

Viewing the Digestive Tract with an Endoscope

A flexible tube called an endoscope is used to view different parts of the digestive tract. When passed through the mouth (as shown on the left), an endoscope can be used to examine the esophagus, stomach, and some of the small intestine. When passed through the anus (right), an endoscope can be used to examine the rectum and the entire large intestine.

Viewing the Digestive Tract with an Endoscope

Why do doctors do endoscopy?

Doctors do GI endoscopy to find and often treat problems in your esophagus, stomach, intestine, and rectum. Even if you're not having symptoms, doctors may do endoscopy to screen for serious problems like colon cancer, which can be treated if found.

Doctors can use endoscopy to:

  • Find out why you're having certain symptoms

  • Check people of a certain age for problems—for example, if you're over 45, doctors may do colonoscopy to screen you for colon cancer

  • Treat certain problems using small tools that can fit through the endoscope

Some procedures doctors can do through an endoscope include:

How do I get ready for an upper endoscopy?

  • You'll have to stop eating and drinking before the test—your doctor will tell you exactly when

  • Your doctor will tell you whether you may take some of your regular medicines the morning of the test

How do I get ready for a lower endoscopy (colonoscopy)?

  • You'll have only liquids the day before the test, no solid food

  • You'll have to stop eating and drinking the night before the test—your doctor will tell you exactly when

  • Your doctor will tell you whether you may take some of your regular medicines the morning of the test

  • You'll take medicines to get all the stool (poop) out of your intestines the day before the test—the medicine may be pills, liquids you drink, or liquid you put up your butt (an enema)

What happens when I have endoscopy?

During your upper endoscopy or colonoscopy, you lie down and have instruments attached to your body to measure your blood pressure, pulse, and oxygen level in your blood during the test.

  • You'll have an IV put into your arm for fluids and medicines

  • For upper endoscopy, doctors will put a numbing medicine in your throat

  • You'll get IV medicine to keep you calm and relaxed or put you to sleep

Your doctor will gently thread the tube into your body.

Your doctor will be able to see problems such as:

  • Redness

  • Open sores (ulcers)

  • Swelling

  • Unusual growths

The lining and inner layers of your digestive system (except for the lower part of your anus) don't have nerves that feel pain, so you won't feel pain even if you're not asleep during these tests.

Endoscopy takes about 15 to 30 minutes. After you wake up and feel normal, you'll be able to go home with a friend or family member and rest until the following day.

Is endoscopy safe?

Endoscopy is usually very safe. Problems are rare but can include:

  • Feeling tired from the relaxing medicine

  • Uncomfortable feeling in the part of the body that was examined

  • A small amount of bleeding

  • Injury to the examined area

  • Scratchy throat after upper endoscopy

  • Passing a lot of gas after lower endoscopy

Call your doctor right away if you have any of these symptoms after endoscopy:

  • Fever

  • Severe pain in your belly

  • Chest pain or shortness of breath

  • Vomiting, especially if it's dark or bloody

  • Blood in your stool or black stool

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