Esophageal Manometry and Ambulatory Esophageal pH Testing

by James B. Ehrlich, MD

Heartburn, chest discomfort, and difficulty swallowing may indicate problems with the esophagus.

Many people who experience heartburn, chest discomfort or swallowing difficulties may have already consulted their physician for evaluation and treatment of these symptoms. The terms "UGI X-ray" and "Upper endoscopy or Gastroscopy" may be familiar to you as they are common and widely used tests. UGI X-rays allow for radiologic evaluation of the esophagus, stomach, and intestine, and may reveal anatomic or structural abnormalities, such as a hiatus hernia or ulcer. Upper endoscopy permits the physician to directly visualize the same area and collect biopsy specimens for pathologic evaluation.

There are other studies that supplement these tests in patients with difficult to treat problems such as heartburn not responsive to conventional medical treatment, asthma due to gastroesophageal reflux (GERD), unexplained chest pain (not due to a heart problem), or swallowing difficulties.

Manometry and pH measurement test the functioning of the esophagus.

Two of these tests are esophageal manometry and esophageal pH testing. Unlike X-rays or endoscopy, which provide visualization of the anatomy of the esophagus and stomach, manometry and pH studies are physiologic studies which measure different aspects of how the esophagus and stomach function.

Esophageal Manometry

Esophageal manometry tests the motor function of the esophagus and the Lower Esophageal Sphincter (LES). It also tests the Upper Esophageal Sphincter when this test is indicated. The esophagus is a long muscular tube responsible for the transit of food and liquid from the mouth to the stomach. This process is called peristalsis and requires proper coordination of the esophageal muscle and adequate pressure to push food and liquid along the length of the esophagus. A normally functioning esophagus performs this task effortlessly and without any sensation to the patient. However, if the esophagus does not function properly, several symptoms can result, including chest pain while eating, a sensation of food getting stuck, or unexplained chest pain, even when not eating, heartburn, and regurgitation of food contents into the esophagus and mouth.

The lower esophageal sphincter is a one-way valve between the esophagus and stomach.

The Lower Esophageal Sphincter is located at the end of the esophagus, just above the opening to the stomach. It acts as a one way valve which opens to allow food to enter the stomach from the esophagus, and then closes to prevent stomach contents from going back into the esophagus. When the LES is weak or doesn’t function properly, acid and food contents from the stomach can go back into the esophagus causing heartburn, chest pain, and reflux of contents into the mouth causing further symptoms such as laryngitis, dental cavities, chronic earache, sinus problems, and asthma.

Esophageal manometry is a test that takes approximately 30 minutes and does not have to be performed in the hospital. There is no anesthesia required and the patient can leave the office immediately after the test and resume his or her normal activities. The test is performed by passing a thin tube, known as a manometry catheter, through the nose into the esophagus. The patient may have his or her throat sprayed with an anesthetic to minimize discomfort, but this is usually not necessary. During the test, the patient is lying down and will be asked to take small sips of water which are given with a spoon or a syringe. The manometry catheter is connected to a computer which records the pressure waves of the esophagus during the swallowing process.

A complete analysis of the test may take several days. The interpretation of the test by the physician may help determine the cause of the patient’s problem. The test may reveal that the LES is too relaxed or may not relax properly. Other common abnormalities include low pressure in the esophagus leading to ineffective peristalsis, spasm of the esophagus, or absence of transmission of the peristaltic wave. Depending on the findings, specific therapy may be initiated or further testing may be advised. For example, if the Lower Esophageal pressures are low, this may suggest acid reflux into the esophagus (acid going back from the stomach into the esophagus) as the cause to the patient’s problem. To confirm this, a pH study should be performed, as described below.

24 Hour Ambulatory pH Testing

pH is a measure of acid content. Persons with excessive heartburn often have too much acid backing up into the esophagus. pH testing can confirm this and help guide therapy.

pH is a term used to describe the degree of acidity, in this case, in the stomach and the esophagus. Neutral pH (such as water and blood) is around 7. The lower the number, the more acid there is. The stomach will usually have a pH of around 2. The esophagus will usually have a pH of around 7, but it is not uncommon for there to be brief periods of a lower pH in the esophagus, such as a pH of 4. This occurs when we eat acidic foods or beverages and also when there are brief periods of gastric acid coming into the esophagus. When you get mild heartburn, which is very common, or when you belch, acid often leaves the stomach briefly, but the esophagus will usually clear the acid back to the stomach in a short period of time. This situation is not abnormal, unless it happens very frequently or the acid stays in the esophagus for a long period of time.

People who have frequent heartburn or other symptoms of reflux, that do not respond to normal medical treatment, may be advised to have a 24 hour ambulatory pH test. As the name implies, this test takes 24 hours. The patient makes a brief visit to physician performing the test and a very thin catheter is placed through the nose and passed into the esophagus to an appropriate level that is usually determined by esophageal manometry. The catheter is taped along side the cheek, behind the ear and passed under the patient's shirt to minimize it interfering with the patients normal activities. The other end of the catheter is connected to a small computer, around the size of a Walkman tape player, which is held in place by a belt at the waist. The patient will then be instructed to perform all their normal activities, including eating, mild exercising, going to work (if they don’t mind too many questions), and sleeping. The patient returns the next day to have the catheter removed and can then leave. The information on the computer will be transferred to a desktop computer and analyzed.

The information acquired from this test will show how frequently acid refluxes into the esophagus, what activities cause the reflux, how long it stays in the esophagus, and what symptoms occur during these episodes (such as heartburn, belching, acid taste in the mouth, chest pain). The study may give the physician useful information which can aid in medical treatment for the patient’s problem. For example, if the patient is studied while on medication, it may show whether that medication is doing what it is supposed to by suppressing acid or keeping it out of the esophagus. Results of this test may suggest that different medication be used, or higher doses be given, or giving the same medications, but at different times in the day. Some patients with severe reflux who do not respond to conventional medical therapy may benefit from certain surgical procedures, such as repairing a hiatus hernia. Esophageal pH testing is usually requested prior to any consideration of surgery.


Chronic heartburn, unexplained chest pain, and swallowing difficulties are common problems that are often treated effectively with the help of your physician. When these symptoms are difficult to control or not successfully controlled, advanced studies such as Esophageal Manometry and 24 Hour Ambulatory pH testing may be indicated to help determine why your symptoms may persist and what additional steps can be taken to help correct the problem. Esophageal Manometry and Esophageal pH testing are safe, minimally invasive tests that can be performed in an outpatient setting without anesthesia and very little discomfort.

Dr. Ehrlich is a member of Gastroenterology of Westchester, PC, with an office in Bronxville, NY (telephone 914-779-3333). Dr. Ehrlich's special interest is in disorders of the esophagus. You may send email to Dr. Ehrlich for more information.

return to top Top of page

arrow17 return to Return to home