Endoscopes

Last updated: October 19, 2008.

Think back to what medicine was like only a hundred years ago. Suppose you're a 19th-century physician and a patient knocks on your door complaining of acute pains in their abdomen. You can ask them questions and examine their body with your hands. You can prescribe them drugs and watch how they respond over days, weeks, or months. But ultimately, unless you cut their body open and examine it directly, you have no way of knowing with complete confidence what's wrong. So do you take a risk, do nothing, and wait to see how things turn out? Or do you operate immediately, potentially wasting time and money and putting your patient through disruptive and traumatic surgery? Thanks to medical imaging devices such as endoscopes, decisions like this are a thing of the past: physicians can see exactly what's going on inside your body without cutting it open. Let's take a closer look at how they work!

Photo: Endoscopes not only allow physicians to see into your body, they can also be used to carry out delicate, minor surgery. You can see the three key tubes in an endoscope at work here. The big black tube in the middle carries the image of the patient's body into the doctor's eye. The smaller black tube on the right, coming down at an angle, is where light shines into the endoscope from a lamp (not shown) in the operating room. The tube on the upper left at the top (with the silver crown) is where tiny surgical tools can be inserted. The doctor is pressing on a cable that enters the patient's body through this tube to take a tissue sample. Photo by courtesy of National Institutes of Health (NIH).

What is an endoscope?

An endoscope is a bit like a bendy telescope a physician can use for seeing inside one of the body's cavities. Unlike a telescope, which is a very rigid tube, the part of an endoscope that enters a person's body is relatively flexible. It consists of several thick optical cables, each of which may be made from thousands (or tens of thousands) of separate glass or plastic strands. Generally, one of the cables carries light from a bright lamp in the operating room into the body, illuminating the cavity where the endoscope has been inserted. A separate cable carries reflected light back out again, either into an eyepiece that the physician looks down or into a video camera that displays what's happening on a television monitor.

Photo: Images of stomach cancer seen through a medical endoscope. Photo by courtesy of National Institutes of Health (NIH) Image Bank.

In some endoscopes, further cables carry extremely small surgical tools, such as forceps or lasers, to the affected part of the body. Surgeons can manipulate these tools remotely while watching what they're doing through the endoscope eyepiece or on the TV monitor—for example, to take tissue samples called biopsies. This procedure is called minimally invasive surgery and it's simpler, quicker, less expensive, and far less traumatic than conventional operations. However, it still generally needs the patient to have an anesthetic and it's not always without drawbacks and complications.

Who invented endoscopes?

Attempts to see inside the body with crude endoscopes date back to the late 19th century, but the modern endoscope is a more recent invention. The basic technology was developed in the early 1950s by English physicist Harold Hopkins (1918–1994) and his Indian-born student Narinder Kapany (1927–), who'd been asked for help by a group of surgeons. After a great deal of research, Hopkins and Kapany developed a way of making flexible pieces of glass that became known as optical fibers—thicker versions of modern fiber-optic cables that are now so widely used in telecommunications.

By the end of the 1950s, three University of Michigan scientists (Lawrence Curtiss, Basil Hirschowitz, and Wilbur Peters) had used optical-fiber technology to build an instrument called a gastroscope that could be used to see inside a patient's stomach. The same technology was later used to study other body cavities.

What are endoscopes used for?

"Endoscope" is the generic name for an instrument used to look inside any part of the body in this way. Endoscopes used for specific forms of examination have the following names:

• Arthroscope: Joints
• Bronchoscope: Esophagus and lung
• Colonoscope: Colon and bowel
• Coloposcope: Vagina and cervix
• Cystoeurethroscope: Bladder and urethra
• Cytoscope: Bladder
• Duodenoscope: Small intestine
• Esophagogastroduodenoscope: Esophagus, stomach and small intestine
• Fetoscope: Womb
• Gastroscope: Stomach
• Hysteroscope: Womb
• Laparoscope: Abdomen
• Laryngoscope: Larynx
• Peritoneoscope: Peritoneum
• Proctosigmoidoscope: Lower part of the large intestine
• Sigmoidoscope: Large intestine
• Thoracoscope: Thorax
• Ureteroscope: Pelvis and ureter

Endoscopes aren't just used for medical diagnosis: they're incredibly useful for inspecting inaccessible areas of buildings or parts of machines where people can't easily see. Industrial endoscopes used in this way are called borescopes and fiberscopes.

How are fiber-optic cables different from endoscopes?

You might be wondering what's the difference between fiber-optic cables used in endoscopes and those used for carrying telephone calls, cable TV, and Internet data. Telecommunications cables are designed to carry data in digital form over very long distances; by contrast, the cables used in endoscopes carry pictures over much shorter distances and in analog form. In other words, while telecoms cables carry binary data (long strings of zeros and ones) that represent everything from MP3 music tracks to digital photos of rock stars, endoscope cables carry the actual pictures of someone's insides!