What is gastroenterology?

This page was reviewed under our medical and editorial policy by

Maurie Markman, MD, President, Medicine & Science

This page was updated on July 12, 2022.

Gastroenterology is a branch of medicine focused on gastrointestinal diseases, such as Crohn's disease, irritable bowel syndrome and pancreatitis. Gastroenterologists are trained to diagnose and treat a broad spectrum of disorders that affect the digestive tract, from the mouth to the anus. The gastroenterology team at City of Hope specializes in diagnosing and treating cancer of the stomach, gallbladder, large and small intestine.

Cancer Treatment Centers of America® (CTCA) is now City of Hope®, joining forces to expand patient access to personalized, comprehensive cancer care.

What is a gastroenterologist?

A gastroenterologist is a type of doctor trained to diagnose and treat problems related to the many organs involved in the body’s digestive, or gastrointestinal (GI), tract.

What does a gastroenterologist do?

Digestion is no simple task. Food and drink travel through a long and complicated system of organs, which help absorb nutrients and filter out waste, before leaving the body.

Gastroenterologists have specialized knowledge of this complex digestive process and may treat issues related to the:

  • Esophagus
  • Stomach
  • Small intestine
  • Colon and rectum
  • Pancreas
  • Gallbladder
  • Bile ducts
  • Liver

With its many facets, the digestive tract may host a number of problems at times. Some conditions that a gastroenterologist may play a role in treating include:

  • Colon polyps
  • Hepatitis
  • Heartburn or gastroesophageal reflux disease (GERD)
  • Peptic ulcers
  • Colitis
  • Gallbladder disease
  • Biliary tract disease
  • Nutritional deficiencies
  • Irritable bowel syndrome (IBS)
  • Pancreatitis

Gastroenterologists may also play a role in diagnosing or treating cancer in any of the digestive organs. These include:

What procedures do gastroenterologists perform?

Gastroenterologists perform many different diagnostic procedures or treatments, depending on the condition or area affected.

Within the gastroenterology field, some doctors may specialize in performing particular procedures or treating specific organs. On top of their gastroenterology training, a gastroenterologist may receive additional training for specific types of endoscopic procedures, which use a long instrument with a tiny camera attached (an endoscope) to look inside organs or areas of the body. A hepatologist is trained to focus specifically on diagnosing and treating problems in the liver.

Below are some of the more common procedures performed by gastroenterologists.

  • Colonoscopy: Examining the colon and rectum using a thin, lighted tube with a camera
  • Upper endoscopy: Looking inside the esophagus, stomach and the upper part of the small intestine using an endoscope
  • Enteroscopy: Examining the small intestine using a longer or other type of endoscope
  • Endoscopic retrograde cholangiopancreatography: Examining or treating problems in the liver, pancreas, bile ducts and gallbladder using a combination of an endoscope, an X-ray and an injected dye that creates contrast in the X-ray images
  • Endoscopic ultrasound: Examining the digestive tract and adjacent organs beyond the surface level and in greater detail than a regular endoscopy, using an endoscope with a built-in ultrasound device
  • Percutaneous endoscopic gastrostomy: Inserting a feeding tube in patients with appetite or swallowing problems, using an endoscope to assist with the placement

These are only a few of the procedures that involve a gastroenterologist. During some of these procedures, doctors may take samples of abnormal tissue, such as suspected cancer, or remove abnormal tissue, such as colon polyps or tumors.

Once a gastric cancer has been diagnosed, some of the procedures that may be performed by City of Hope gastroenterologists include:

Fiducial markers: Fiducial markers are placed inside a tumor before radiation therapy. Using these markers allows for more precise targeting of tumors and helps reduce harm to healthy tissue.

Gastrostomy tube (G-tube): This catheter is inserted through the abdomen and into the stomach. Patients who receive a gastrostomy tube may be having difficulty digesting food or may aspirate food into their lungs.

Esophagogastroduodenoscopy (EGD): Commonly called an upper endoscopy, this procedure is used both to diagnose and treat conditions of the upper gastrointestinal tract. The doctor views the lining of the esophagus, stomach and beginning of the small intestine using real-time images from a camera attached to a thin, flexible tube called an endoscope. An EGD may be used to treat cancer of the esophagus, stomach and small intestine.

Nd: YAG laser: The Nd: YAG (neodymium: yttrium-aluminum-garnet) laser shrinks or destroys tumors and/or helps relieve symptoms in difficult-to-reach areas of the body, such as the lungs, esophagus or colon. A high-power laser beam burns, or “vaporizes,” the tumor. The cancer is evaporated, and the vapor is suctioned out through an endoscope or bronchoscope. The Nd: YAG laser is often used to treat large, obstructive masses that causes symptoms such as bleeding or obstruction but cannot be removed surgically. For example, the laser may be used to remove an obstruction in the esophageal tract to relieve swallowing difficulties, or in the airways to improve breathing.

Needle-based ablation: Needle-based ablation is a localized cancer treatment that uses high-energy radio waves or microwaves to heat and destroy cancerous cells.

What kind of training does a gastroenterologist have?

Gastroenterologists undergo rigorous training, including medical school, an internal medicine residency and a gastroenterology fellowship. This equates to up to 10 years of training before being certified as a gastroenterologist.

  • A doctor pursuing a career in gastroenterology must first graduate from medical school.
  • After that, a prospective gastroenterologist completes a three-year residency in internal medicine to practice diagnosing and treating a broad spectrum of medical conditions under the supervision of more experienced doctors.
  • After completing medical school and three years of residency, a prospective gastroenterologist must be accepted into a gastroenterology fellowship to undergo specialized training. Gastroenterology fellowships tend to take two to three years and involve working under experts in the field to gain a deep knowledge of digestive diseases and how to diagnose and treat them.

Newly trained gastroenterologists must complete their fellowship before seeking certification from the American Board of Internal Medicine. Certification, or becoming “board-certified” in gastroenterology, requires successful performance on the gastroenterology board certification test.

What should you expect during a visit with a gastroenterologist?

A visit to the gastroenterologist may be very different depending on its purpose. Reasons may include:

A screening test: Many people, especially older adults, see a gastroenterologist for screening tests, such as a colonoscopy, that check for cancer and other problems in the digestive tract. Depending on the test, the patient may get a sedative or pain medication.

A specific digestive tract issue: Primary care physicians may refer patients to a gastrointestinal specialist for reasons such as undiagnosed abdominal pain or a case of heartburn that isn’t improving after treatment. If heartburn is suspected, for example, the gastroenterologist may ask about symptoms and recommend an endoscopy to examine the esophagus.

Cancer or suspected cancer in the digestive tract: Gastroenterologists are often involved when cancer is suspected or confirmed in the gastrointestinal tract, such as cancer of the esophagus, stomach, liver or pancreas. The gastroenterologist may recommend an upper endoscopy to look for cancer and take samples of potentially cancerous areas in the stomach. These samples are tested in a lab to see whether they contain cancer.

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