The esophagus is the muscular tube through which food passes on its way from the mouth to the stomach. The main function of the esophagus is to propel food into the stomach. To ensure that food does not move backward—a condition known as reflux—sphincters (constricting ring-shaped muscles) at either end of the esophagus close when the food is not passing through them in a forward direction. Esophageal function tests are used to determine whether the sphincters are working properly.
The esophagus has two sets of sphincters at its upper and lower ends. Each of these muscular rings must contract in an exact sequence for swallowing to proceed normally. The upper esophageal sphincter normally stops the contents of the stomach from moving backward into the pharynx and larynx (voice box). The lower esophageal sphincter guards against stomach acid moving upward into the esophagus. The lower sphincter should be tightly closed except to allow food and fluids to enter the stomach.
The three major symptoms occurring with abnormal esophageal function are difficulty with swallowing (dysphagia); heartburn; and chest pain. Doctors perform a variety of tests to evaluate these symptoms. Endoscopy, which is not a test of esophageal function, is often used to determine if the lining of the esophagus has any ulcers, tumors, or areas of narrowing (strictures). Many times, however, endoscopy only shows the doctor if there is an injury to the esophageal lining; it does not always provide information about the cause of the problem. Tests that measure the functioning of the esophagus are sometimes needed in addition to endoscopy. There are three basic types of tests used to assess esophageal function:
This study is designed to measure the pressure changes produced by contraction of the muscular portions of the esophagus. An abnormality in the function of any one of the segments of the esophagus can cause difficulty in swallowing (dysphagia). A manometric examination is most useful in evaluating patients when an endoscopy yields normal results.
During manometry, the patient swallows a thin tube carrying a device that senses changes in pressures in the esophagus. Readings are taken at rest and during the process of swallowing. Medications are sometimes given during the study to aid in the diagnosis. The results are then transmitted to recording equipment. Manometry is most useful in identifying diseases that produce disturbances of motility or contractions of the esophagus. In 2003, a solution containing five drops of peppermint oil in 10 mL of water was found to improve the manometric features of diffuse esophageal spasm (DES). The peppermint oil solution eliminated simultaneous esophageal contractions in all patients in the study.
This procedure measures the esophagus' exposure to acid reflux from the stomach. The test is ideal for evaluating recurrent heartburn or gastroesophageal reflux disease (GERD). Excessive acid reflux may produce ulcers, or strictures resulting from healed ulcers, in addition to the symptom of heartburn.
Normally, acid from the stomach washes backward into the esophagus in small amounts for short periods of time. The lower esophageal sphincter usually prevents excessive reflux in patients without disease. Spontaneous contractions that increase esophageal emptying and production of saliva also act to prevent damage to the esophagus.
Researchers have shown that in the esophagus, the presence of acid is damaging only if it lasts over long periods of time. Therefore, esophageal pH monitoring has been designed to monitor the level of acidity over a 24-hour period, usually in the patient's home. In this way, patients are able to maintain their daily routine, document their symptoms, and correlate symptoms with specific activities. During this period, a thin tube with a pH monitor remains in the esophagus to record changes in acidity. After the study, a computer is used to compare the changes with symptoms reported by the patient.
In addition to esophageal pH monitoring, the doctor may perform a Bernstein test (also known as the acid perfusion test) and an acid clearing test. In the Bernstein test, a small quantity of hydrochloric acid (HCl) is directed into the patient's esophagus. If the patient feels pain from the acid, the test is positive for reflux esophagitis. If there is no discomfort, another explanation must be sought for the patient's symptoms. In the acid clearing test, HCl is also directed into the esophagus. This test, however, measures the patient's ability to quickly swallow the acid. If the patient has to swallow more than 10 times to move the acid down the esophagus, he or she has a problem with esophageal motility.
pH monitoring is usually performed before surgery to confirm the diagnosis and to judge the effects of drug therapy. In 2003, studies showed that integrated esophageal and gastric acidity provided better quantitative measures of esophageal dysfunction in GERD than conventional measurements of pH. This finding may suggest better ways to evaluate the effectiveness of different treatments for GERD.
X-ray tests of esophageal function fall into two categories: (1) tests performed with barium and a fluoroscope; and (2) those performed with radioactive materials. Studies performed with fluoroscopy are especially useful in identifying structural abnormalities of the esophagus. Sometimes the patient is given a sandwich or marshmallow coated with barium in order to identify the site of an obstruction. Fluoroscopy can diagnose or provide important information about a number of disorders involving esophageal function, however, including cricopharyngeal achalasia (a swallowing disorder of the throat); decreased or reverse peristalsis; and hiatal hernia.
During fluoroscopy, the radiologist can observe the passage of material through the esophagus in real time, and also make video recordings. These observations are particularly useful when the swallowing symptoms appear to occur mostly in the upper region of the esophagus. The most common cause of difficulty swallowing is a previous stroke, although other diseases of the neuromuscular system (like myasthenia gravis) can produce similar symptoms.
Scans using low-dose radioactive materials are useful because they may demonstrate that food passes more slowly than usual through the esophagus. They can also measure the speed of the bolus' passage. These studies involve swallowing food coated with radioactive material, followed by a nuclear medicine scan. Scans are often used when other methods have failed to make a diagnosis, or if it is necessary to determine the degree of the abnormality.
Patients should not eat or drink anything after midnight before an esophageal function test. Many medications affect the esophagus; doses may need to be adjusted or even discontinued prior to testing. Patients must inform their physician of any and all medications they take, including over-the-counter medications and herbal preparations. They must also tell the doctor about any known allergies.
No special care is needed after most esophageal function tests. Patients can usually return to their normal daily activities following almost all of these tests.
Exposure to x rays, especially in the first three months of a woman's pregnancy, can be harmful to the fetus. Barium swallows may also cause impaction (hardening) of fecal matter. Additionally, although the tubes passed through the esophagus during some of the esophageal function tests are small, and most patients adjust to them quite well, some patients may gag and aspirate (breathe into the lungs rather than passing through the esophagus) some gastric juices.
Normal findings include:
Manometry is used to diagnose abnormalities related to contraction or relaxation of the various muscular regions of the esophagus. These studies cannot distinguish whether injury to either the muscle or nerves of the esophagus is producing the abnormal results—only the final effect on esophageal muscle is identified. The results of this test should be interpreted in light of the patient's entire medical history. For example, there are many diseases that affect the relaxation of the lower esophageal sphincter; one such condition is called achalasia. Achalasia is a frequent finding in individuals with Down's syndrome.
Abnormal results of pH tests can confirm symptoms of heartburn or indicate a cause of chest pain (or rarely, swallowing difficulties). The patient's doctor may want to prescribe or change medications based on these results, or even repeat the test using different doses of medication. As noted above, these studies should be done before surgical treatment of GERD.
X-ray tests can serve to document an abnormality in the esophagus. If the results are negative, other studies may be needed.
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Smout, Andre. "Ambulatory Monitoring of Esophageal pH and Pressure." in Donald O. Castell and Joel E. Richter, eds., The Esophagus , 3rd ed. Philadelphia, PA: Lippincott, 1999.
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American Society for Gastrointestinal Endoscopy (ASGE). Thirteen Elm Street, Manchester, MA 01944-1314. (978) 526-8330. http://www.asge.org .
Illinois Nurses Association—Advanced Practices Registered Nurses (APRNs) Statistics. 105 W. Adams, Suite 2101, Chicago, IL 60603. http://www.illinoisnurses.org/aprn.html .
Society for Gastroenterology Nurses and Associates (SGNA). 401 North Michigan Avenue, Chicago, IL 60611-4267. (800) 245-7462. http://www.sgna.org .
Maggie Boleyn, RN, BSN Lee Shratter, MD