What is a esophageal manometry test?
An esophageal manometry test is a test used to evaluate the function of the esophagus and the lower esophageal sphincter (LES). It must be well understood that this is not a specific test for GERD. Rather, as function is assessed, your physician may see changes that are consistent with GERD or may also discover specific esophageal contraction disorders that may mimic GERD. Approximately 5% of people thought to have GERD actually have one of several esophageal disorders uncovered with an esophageal manometry test. Also, many proven to have GERD by previous pH testing have normal or close to normal manometry studies.
To understand what happens during the manometry test, you must understand what happens when you swallow. In order to pass food, the esophagus must contract in a sequential manner after swallowing. The top end must contract first, then the middle, and then the bottom. This propels the food downward toward the stomach. At the same time, the LES, located at the end of the esophagus and just above the stomach, must open or relax to allow the food to pass into the stomach. All of these events are measured during manometry test in terms of pressure. As part of the esophagus squeezes, it generates pressure. As the LES opens, its pressure lowers from its resting state. The pressure measurements also measure the length of the LES and can detect a hiatus hernia, if present.
How is the test conducted?
The study, which takes about 20 minutes to complete, is conducted by passing a thin flexible tube containing 36 separate pressure sensors gently through the nose into the stomach. During this test, you will be awake, but the nose is numbed with topical medicine. Once the tube is in place, you will be given a small amount of water to swallow. As you swallow, the pressure measurements are processed by a computer and displayed on a screen. After 10 swallows, the test is concluded and the tube is removed. You will immediately be able to return to normal diet and activities.
As noted above, this is not a test for GERD. A pH study usually is required for that. However, in many patients with GERD, a manometry test can reveal important information about your condition:
- A short, low pressure LES is consistent with GERD
- The presence of a hiatus hernia, if one exists.
- In patients with longstanding GERD, the lower esophagus can be damaged and not able to generate its usual pressure, which is readily detected with manometry.
Other esophageal conditions
A manometry test can also diagnose other conditions of the esophagus. Two examples include:
- Achalasia: With this condition, the LES fails to relax. As a result, food cannot pass into the stomach and the patient will experience difficulty swallowing.
- Nutcracker esophagus: This occurs when the esophagus squeezes in sequence, but too vigorously. This can cause chest pain, as well as swallowing difficulty.
There are other esophageal function abnormalities that are apparent only on a manometry test. The key factor is that these “primary esophageal motility disorders” can create the same symptoms as GERD. These disorders are treated differently than GERD, so identifying them is very important. An esophageal manometry test is also required prior to any surgical procedure to treat GERD. This is to ensure that none of these pressure problems exist and that the esophagus functions well enough for a good surgical result.
For more information on an esophageal manometry test, please visit the ASGE patient information webpage.
Reviewed by: Dr. Dengler, RefluxMD Medical Director