Esophagus Tests

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Esophagus Tests

Test Overview

Esophagus tests measure muscle pressure and movement, coordination, and strength of the tube that connects the throat to the stomach (esophagus). They test how well the ring of muscles (sphincters) at the top and bottom of the esophagus work. Esophagus tests also measure the movement and volume of gas, liquid, and solid through the esophagus and its pH (acid or non-acid). See a picture of the esophagus.

The most common esophagus tests include:

  • pH monitoring (esophageal acidity test), which measures the acid content (pH) in the esophagus. A low pH for long periods may mean frequent abnormal backflow (reflux) of stomach acid into the esophagus (gastroesophageal reflux disease, or GERD).
  • Esophageal manometry, which measures the strength and pattern of muscle contractions in the esophagus. This test can find:
    • Weakness in the lower esophageal sphincter (LES), which allows acid to reflux into the esophagus.
    • Weak muscle contractions during swallowing that slow the rate at which food or stomach acid is cleared from the esophagus.
    • Abnormally strong contractions (spasms) that can cause chest pain or the sensation that food is stuck after swallowing (dysphagia).

Either pH or manometry testing can be combined with a test that measures the movement and volume of gas, liquid, and solid through the esophagus (multichannel intraluminal impedance testing, or MII). When MII is combined with manometry (MII-EM), it can show how the muscles of the esophagus are contracting when there is food or liquid in the esophagus. When MII is combined with pH testing (MII-pH), it can detect reflux from the stomach into the esophagus and measure both the volume and the acidity.

Why It Is Done

Tests on the esophagus are done to:

  • Help find the cause of chest pain that is not caused by heart problems (called noncardiac chest pain).
  • Help determine the cause of GERD symptoms for a person who has not been helped by medicine and whose esophagus looks normal during an endoscopy test.
  • Monitor the effectiveness of treatment for GERD.
  • Detect spasms of the esophagus, which can cause chest pain, and problems with the ability of the esophagus to move food down to the stomach (motility problems).
  • Determine whether the esophagus is working normally.
  • To evaluate how the esophagus works before surgery for GERD.

Esophagus tests are usually not done in people with GERD if their symptoms are well controlled with medicine.

How To Prepare

To prepare for an esophagus test:

  • Do not take antacids (such as Tums or Rolaids) for 24 hours before the test.
  • Follow your doctors instructions for using other acid reducers or blockers, such as famotidine (Pepcid) or omeprazole (Prilosec), before the test.
  • Do not drink alcohol or smoke for 24 hours before the test.
  • Do not eat or drink for 8 to 12 hours before testing.
  • Tell your doctor if you have any other problems, such as enlarged esophageal blood vessels (esophageal varices), heart failure, or other heart conditions.

Talk to your doctor about any concerns you have regarding the need for the test, its risks, how it will be done, or what the results may mean. To help you understand the importance of this test, fill out the medical test information form(What is a PDF document?).

How It Is Done

You will be seated. You may be given a spray medicine that numbs your nose and throat. For each esophagus test, a thin, flexible tube will be passed through your nose or mouth to your lower esophagus and stomach. This may make you feel like you have to gag. To help overcome this feeling, concentrate on breathing slowly. Your pulse and blood pressure may be monitored while the tube is being inserted.

pH monitoring

  • A probe that measures pH will be passed through your nose or mouth into your lower esophagus. The probe monitors the pH in your esophagus so your doctor can tell whether the pH drops because of liquid from your stomach backing up into your esophagus.
  • For prolonged pH monitoring, the pH probe is attached to a small recorder. You carry the recorder by a strap around your waist or over your shoulder. The probe measures the pH of your esophagus for up to 24 hours while you go about your routine daily activities. During the monitoring period, you will need to use a diary to keep track of your activities and any symptoms you develop. You may be asked to avoid high-acid foods such as fruit, fruit juice, and tomatoes during the testing period. You will not be able to take a bath, except for a careful sponge bath, or do anything else that might get the monitor wet during the recording period.
  • For wireless pH monitoring, a capsule containing a pH-sensitive transmitter is placed in your esophagus during an endoscopy procedure. You carry a small pager-sized receiver in your pocket or wear it around your waist. During the monitoring period, you will need to use a diary to keep track of your activities and any symptoms you develop. You will be instructed to press the symptom button when you have heartburn, chest pain, or regurgitation. You can bathe during the monitoring period. When the testing period is over, return the receiver and your diary to your doctor for evaluation. The transmitter capsule will pass out of your body in a bowel movement, usually within a few days.

Esophageal manometry

  • You will swallow a small tube attached to instruments (transducers) that measure pressure. The tube has holes in it that sense pressure along the esophagus. It will be positioned in different areas of your esophagus.
  • You may be asked to swallow several times or to drink liquids while pressure measurements are taken.
  • You may be asked to swallow, not swallow, and hold your breath during the test.
  • The results of the manometry test are displayed as a graph with a wave pattern that can be interpreted to determine if the esophagus is functioning normally.

If you have multichannel intraluminal impedance (MII) testing done with either pH or manometry, it will be done in very much the same ways as described above. The catheters used to do MII with pH or manometry testing will include instruments that measure volume of food and liquid in the esophagus as well as pH or pressure.

How It Feels

The local anesthetic sprayed into your nose and throat usually tastes slightly bitter and will make your tongue and throat feel numb and swollen.

When the tube goes through your nose or mouth into your esophagus, you may feel like coughing or gagging. The test may be easier if you try to take slow, deep breaths. You may not like the taste of the lubricant on the tube.

If you have a test that involves adding acid to your stomach, you may have heartburn pain and other symptoms of acid reflux.

If you have the wireless pH monitoring, you may be able to feel the capsule in your esophagus. You will not feel the capsule when it detaches and passes through your intestines and out of your body in your stool.

After the test is over, your nose and throat may feel sore. But this should improve within a day or so.


The chances that you will have problems from an esophagus test are rare.

  • You may get a nosebleed.
  • You may have irregular heartbeats (arrhythmias).
  • The tube may go down the windpipe (trachea) instead of the esophagus as it is being inserted.
  • You may vomit material from your stomach and then breathe it into your lungs (aspiration).
  • The tube may make a hole in the esophagus (perforation).


Esophagus tests measure muscle pressure and movement, coordination, and strength of the tube that connects the throat to the stomach (esophagus). They test how well the ring of muscles (sphincters) at the top and bottom of the esophagus work. Esophagus tests also measure the movement and volume of gas, liquid, and solid through the esophagus and its pH (acid or nonacid). Results are usually available within a few days.

pH monitoring
  • The pH of the esophagus is not acidic.
  • If acid is placed in the stomach, the pH of the esophagus does not go down.
  • The pH of the lower esophagus is frequently acidic.
  • If acid is placed in the stomach, the pH of the lower esophagus goes down.


Esophageal manometry
  • The pressure of the muscle contractions that move food down the esophagus is normal.
  • The muscle contractions follow a normal pattern down the esophagus.
  • The pressure at the lower esophageal sphincter (LES) is normal.
  • Muscle spasms are present in the esophagus.
  • Contractions along the esophagus are weak or uncoordinated.
  • The LES pressure is low.
  • The LES pressure is high and fails to relax after swallowing.


Many conditions can change the results of esophagus tests. Your doctor will discuss any significant abnormal results with you in relation to your symptoms and past health.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

  • Taking certain medicines. Many medicines can affect the results of pH testing or esophageal manometry. Make sure you follow your doctor's instructions about which medicines to stop or to take before and during testing.
  • Smoking or drinking alcohol within 24 hours of the test.
  • Eating or drinking within 8 hours of the test, unless you are having prolonged pH monitoring at home. If you are having prolonged pH monitoring, try to eat normally and do your normal activities.
  • Detachment of the wireless pH capsule before the end of the recording time (usually 24 or 48 hours).
  • Movement of the catheter when you swallow.

What To Think About

  • Occasionally, samples of stomach secretions may be taken during the pH monitoring test.
  • Combining multichannel intraluminal impedance testing with pH (MII-pH) can record reflux, even if it's not acidic. pH testing by itself will only record acidic reflux events.
  • Other tests may be done to help diagnose problems with the esophagus, including upper gastrointestinal (UGI) endoscopy, barium swallow, or upper gastrointestinal studies (upper GI series). For more information, see the topics Upper Gastrointestinal (UGI) Series and Upper Gastrointestinal Endoscopy.


Other Works Consulted

  • American Gastroenterological Association (2005). AGA technical review on the clinical use of esophageal manometry. Gastroenterology, 128(1): 209–224.
  • American Gastroenterological Association (2008). American Gastroenterological Association medical position statement on the management of gastroesophageal reflux disease. Gastroenterology, 135(4): 1383–1391.
  • Chernecky CC, Berger BJ (2008). Laboratory Tests and Diagnostic Procedures, 5th ed. St. Louis: Saunders.
  • Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
  • Hirano I, et al. (2007). ACG practice guidelines: Esophageal reflux testing. American Journal of Gastroenterology, 102(3): 668–685.
  • Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.


ByHealthwise Staff
Primary Medical ReviewerKathleen Romito, MD - Family Medicine
Specialist Medical ReviewerJerome B. Simon, MD, FRCPC, FACP - Gastroenterology
Last RevisedApril 25, 2011

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