In esophageal function studies, special probes are passed into the esophagusthe muscular passage that contracts and relaxes to carry food from the throat to the stomachto evaluate swallowing function. esophageal function studies also measure the efficiency of the lower esophageal sphincter (LES), the circular muscle that acts as a valve to prevent backflow of stomach contents and acid into the esophagus (a disorder known as gastroesophageal reflux).
One or more of the following tests are typically included:
Esophageal manometry records the muscular contractions (swallowing waves) of the esophagus and measures the pressure of the LES (when pressure is too low, reflux of stomach acid occurs; when it is too high, it is difficult for food to pass from the esophagus to the stomach).
The acid reflux test uses a pH probe to measure acid-base levels in the esophagus. Reflux of gastric acid from the stomach causes a noticeable drop in pH levels.
The acid perfusion test (also known as the Bernstein test) attempts to reproduce the symptoms of gastroesophageal reflux by instilling hydrochloric acid into the esophagus. If the acid causes discomfort, then gastroesophageal reflux is indicated; if not, a cause other than reflux is responsible for your symptoms.
The acid clearing test measures the ability of the esophagus to clear itself of hydrochloric acid. People with normal esophageal function are able to clear the acid in less than 10 swallows.
Purpose of the Esophageal Function Studies
- To measure the pressure inside the lower part of the esophagus
- To identify and evaluate esophageal disorderssuch as gastroesophageal reflux, diffuse esophageal spasm, and esophagitis (inflammation of the esophagus)in people with symptoms such as heartburn, chest pain, or difficulty swallowing
- To distinguish the pain caused by heartburn from similar pain caused by cardiac disorders
Who Performs Esophageal Function Studies
- An esophageal technician in an endoscopy laboratory.
Special Concerns about Esophageal Function Studies
- If gastroesophageal reflux is suspected, a barium swallow or esophagogastroduodenoscopy may first be used to establish a diagnosis. Esophageal function studies are typically done only if the initial treatment fails to relieve symptoms.
- A number of medications can interfere with the results of these tests by either decreasing or increasing gastric acid secretion or relaxing the LES and promoting reflux.
- Eating before this test may interfere with results.
- The acid perfusion test should not be done in people with esophageal varices (abnormally dilated blood vessels), congestive heart failure, and certain other cardiac disorders.
Before the Esophageal Function Studies
- Be sure to inform your doctor of any heartburn medications or other drugs you regularly take. You may be advised to discontinue certain drugs before the test.
- Avoid tobacco and alcohol for 24 hours before the test.
- Do not eat or drink anything for at least 8 hours before the test.
What You Experience during Esophageal Function Studies
- Immediately before the test, your blood pressure and pulse are taken. A local anesthetic may be sprayed into your throat.
- Very thin, soft tubes are passed into your nose or mouth, down through your esophagus, and into your stomach. (You may feel a gagging sensation initially, but it will pass.)
- One of the tubes, called a manometry probe, is attached to a pressure transducer that records pressures in the LES and esophagus as the probe is slowly withdrawn from the stomach.
- Next, you are asked to swallow water, and the probe records the swallowing waves of the esophagus. The probe is withdrawn.
- For the acid reflux test, another thin tube with a pH meter at the tip is used, and you will be asked to perform several maneuvers (such as drawing your knees to your chest). The movements may be repeated after hydrochloric acid is instilled through the probe into your stomach. If the probe registers a drop in pH, gastroesophageal reflux is indicated.
- For the acid perfusion test, hydrochloric acid and salt water are alternately instilled through the pH probe into the esophagus. Tell the examiner if and when you experience any discomfort or chest pain; if symptoms occur with the acid, but not the salt water, you may have an inflamed esophagus due to chronic reflux.
- For the acid clearing test, hydrochloric acid is instilled through the pH probe into the esophagus and you will be asked to swallow about every 30 seconds. If it takes more than 10 swallows to clear the acid, reflux is indicated.
- These tests usually take from 30 minutes to 1 hour. In some cases, you will remain in the hospital for 12 to 24 hours while a probe continuously measures acidity in your esophagus.
Risks and Complications of Esophageal Function Studies
- The tube in the esophagus may increase saliva production (salivation), causing a risk for aspiration of stomach contents into the lungs or aspiration pneumonia, especially in people with swallowing difficulties.
After the Esophageal Function Studies
- You may experience a sore throat, which can be eased with soothing lozenges.
- Resume your usual diet and any medications withheld before the test.
Results of Esophageal Function Studies
- Your doctor will review the test results and consider them along with your symptoms to reach a diagnosis.
- If results indicate gastroesophageal reflux, certain lifestyle and dietary changes will be prescribed, as well as medications to reduce stomach acid secretion.
The Johns Hopkins Consumer Guide to Medical Tests
Simeon Margolis, M.D., Ph.D., Medical Editor
Updated by Remedy Health Media