Esophageal manometry is a test to measure the pressure inside the lower part of the esophagus.

Esophageal motility studies; Esophageal function studies

During esophageal manometry, a thin, pressure-sensitive tube is passed through your mouth or nose and into your stomach. Once in place, the tube is pulled slowly back into your esophagus.

When the tube is in your esophagus, you will be asked to swallow. The pressure of the muscle contractions will be measured along several sections of the tube.

While the tube is in place, other studies of your esophagus may be done. The tube is removed after the tests are completed. The test takes about 1 hour.

You should not have anything to eat or drink for 8 hours before the test.

You may have a gagging sensation and some discomfort when the tube is put into place.

When you swallow, muscles in your esophagus contract to help push food toward your stomach. Valves, or sphincters, inside the esophagus open to let food and liquid through, and then close to prevent food, fluids, and gastric acid from moving backward. The sphincter at the bottom of the esophagus is called the lower esophageal sphincter or LES.

The purpose of esophageal manometry is to see if the esophagus is contracting and relaxing properly. The test helps diagnose any swallowing problems. Your health care provider may request that this test be performed if you have symptoms of:

• Acid reflux (heartburn or nausea after eating)
• Problems swallowing (feeling like food is stuck behind the breast bone)

The LES pressure and muscle contractions are normal when you swallow.

Abnormal results may indicate:

• Achalasia -- a problem with the esophagus that affects its ability to move food toward the stomach
• A weak low esophageal sphincter, which causes acid reflux
• Diffuse esophageal spasm -- abnormal contractions of the esophagus muscles that do not move food effectively to the stomach

The tube in the esophagus may cause increased salivation, which raises your risk for aspiration. This can lead to lung injury or aspiration pneumonia.

In general, people with swallowing difficulty are at higher risk for aspiration.

Wilson JF. In the clinic: gastroesophageal reflux disease. Ann Intern Med. 2008;149:ITC2-1-ITC2-15.

Richter JE, Friedenberg FK. Gastroesophageal reflux disease. In: Feldman M, Friedman LS, Brandt LJ, eds. Sleisenger & Fordtran's Gastrointestinal and Liver Disease. 9th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 43.