GERD Tests
Updated on 7/23/09
A number of diagnostic tests are used to confirm the presence of GERD. This section contains more information on:
Upper endoscopy
Upper endoscopy involves the examination of the esophagus, stomach, and first part of the small intestine with a flexible plastic tube, called an endoscope, that is equipped with a tiny camera. The endoscope projects pictures of the organs on a video monitor.
Endoscopy is the best test for the evaluation of reflux-induced esophageal injury. It is essential for the diagnosis of esophagitis and Barrett's esophagus, a condition in which the lining of the esophagus transforms into tissue more like that which lines the intestines and which in some people is a precursor to cancer. It is a good test for the diagnosis of an esophageal stricture, although strictures that narrow the esophagus to only a limited degree may be missed, and it permits treatment of an esophageal stricture by dilation or stretching. The doctor can also use forceps through the tip of the endoscope to remove a tiny piece of tissue for biopsy to rule out other conditions, such as growths or organisms that can infect the organs.
pH monitoring
Continuous pH monitoring records the pH (or level of acidity) over a prolonged period of up to 24 to 48 hours. An acid-sensitive catheter or probe is placed through the nose into the esophagus and transmits changes in esophageal pH to a small monitoring device. It provides information on the severity and pattern of reflux and correlates it with the patient's symptoms. The information is helpful both to confirm the diagnosis and to tailor therapy for the individual patient.
Continuous pH monitoring is considered the best test for the diagnosis of GERD. However, there is a 10 percent false-negative rate, meaning that the patient actually has GERD, but the test fails to find it. The results must, therefore, be interpreted in the context of the patient's symptoms.
A second type of pH testing involves placing a small pH-sensing capsule near the bottom of the esophagus during upper endoscopy. Once it is placed, the capsule transmits pH information to a recorder worn by the patient for 48 hours. The recorder stores information about the pattern and severity of the reflux and correlates it with the patient’s symptoms; this data can be downloaded and analyzed by the physician. The capsule in the esophagus falls off in a week or two and passes (usually unnoticed) into the stool. This test can be helpful in determining how much acid reflux is occurring or to see how well a patient is responding to treatment.
Esophageal manometry
Esophageal manometry, also referred to as esophageal motility studies, involves the placement of a pressure-sensitive catheter into the esophagus. The test permits evaluation of the strength and coordination of muscle contractions, as well as the strength and relaxation function of the lower esophageal sphincter. Although low LES pressure is suggestive of GERD, the condition may also occur in patients with normal LES pressure. Therefore, the results of esophageal manometry are not reliable for the diagnosis of GERD.
Manometry is usually used prior to esophageal pH monitoring (see below) to determine the level of the esophagus at which the pH probe should be placed. Many authorities consider manometry an essential part of assessment in patients being considered for antireflux surgery, helping to determine whether surgery is appropriate and what specific surgical procedure should be performed.
Impedance testing
Impedance testing is a new technique that can detect reflux of nonacid contents and assess whether swallowed food passes through the esophagus in a normal manner. It is often performed at the same time as pH monitoring and esophageal manometry. It works by measuring changes in electrical current as substances pass through the esophagus.
Barium esophagram
In this X-ray study, the structure and function of the esophagus are evaluated. It is often the first test used in patients who are reporting difficulty swallowing, which may be a sign of complications resulting from chronic GERD. The patient swallows a white chalky substance, which coats the esophagus and reveals structural abnormalities when the X-ray is performed. The test might take about an hour and generally produces no side effects.
A barium esophagram is very effective at diagnosing a stricture or other causes of obstruction in the esophagus. It's also used to spot a hiatal hernia and permits the evaluation of esophageal motor function. However, it is a poor test for documenting inflammation of the esophagus, and it's unreliable in detecting reflux.
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