When Are Diagnostic Tests for GERD Ordered?
A doctor may recommend one or more GERD diagnostic tests in the following situations.
- Symptoms do not improve after four to eight weeks of proton pump inhibitor (PPI) therapy medications that suppress stomach acid production
- Symptoms are atypical and do not clearly point to GERD, such as chronic cough, hoarseness, difficulty swallowing, or non-cardiac chest pain
- Symptoms suggest possible complications of long-term acid reflux, such as esophageal stricture (narrowing) or Barrett's esophagus (pre-cancerous changes to the esophageal lining)
- The diagnosis should be confirmed before recommending surgery for GERD
- Symptoms return after surgical treatment for GERD
Upper Endoscopy (EGD Esophagogastroduodenoscopy)
What It Is
Upper endoscopy, also called EGD (esophagogastroduodenoscopy), is a procedure in which a physician passes a an endoscope - a thin, flexible tube which has a camera at the tip, through the mouth and down the throat to visually examine the esophagus, stomach, and the upper part of the small intestine (duodenum).
What It Detects
Upper endoscopy does not directly measure acid reflux. Instead, it looks for the physical damage that chronic acid exposure causes to the esophageal lining. Findings may include the following.
- Esophagitis inflammation and redness of the esophageal lining caused by repeated acid exposure
- Erosions and ulcers areas where the esophageal lining has been worn away by acid
- Esophageal stricture narrowing of the esophagus from repeated scarring, which causes difficulty swallowing
- Barrett's esophagus a pre-cancerous change in the esophageal lining cells that occurs in some people with long-standing GERD and requires regular surveillance
- A hiatal hernia is a condition in which some part of the stomach pushes up through the diaphragm into the chest cavity, which is commonly associated with GERD
When It Is Recommended
Upper endoscopy is recommended when a patient has alarm symptoms such as difficulty swallowing, unexplained weight loss, vomiting blood, or black stools or when GERD symptoms have been present for five or more years without adequate assessment for complications, according to the IFFGD (2023). A small tissue sample (biopsy) may be taken during the procedure to test for Barrett's esophagus or other abnormalities.
What to Expect
The procedure is performed under light sedation. Patients fast for several hours beforehand. The procedure itself takes around 15 to 30 minutes, and most people are discharged the same day after the sedation wears off.
Ambulatory pH Monitoring
What It Is
Ambulatory pH monitoring is considered the most accurate test for directly confirming abnormal acid reflux. It measures the actual acidity level inside the esophagus over a continuous 24- to 48-hour period, capturing how often stomach acid enters the esophagus, how long acid episodes last, and whether acid episodes coincide with the patient's reported symptoms.
Types of pH Monitoring
There are two main methods of ambulatory pH monitoring.
Catheter-based pH monitoring: A thin, flexible tube is passed through the nose and positioned just above the lower esophageal sphincter (the muscle valve between the esophagus and stomach). The tube connects to a small recording device worn around the waist. The patient goes about normal daily activities eating, sleeping, and exercising while the device records pH levels continuously for 24 hours.
Wireless pH capsule (Bravo system): A small pH-sensing capsule is clipped to the esophageal wall during an upper endoscopy. The capsule transmits pH data wirelessly to a handheld recorder for 48 to 96 hours, then detaches naturally and passes through the digestive tract. This method is more comfortable than catheter monitoring and provides a longer recording period.
What Results Show
A pH below 4 (indicating the presence of stomach acid) in the esophagus for more than 4 percent of the total monitoring period is generally considered abnormal and consistent with GERD, according to IFFGD (2023). The test also generates a DeMeester score a composite measure of acid exposure which helps doctors quantify the severity of acid reflux.
Esophageal Manometry
What It Is
Esophageal manometry measures the pressure and movement patterns of the esophageal muscles during swallowing. It assesses how well the lower esophageal sphincter (LES) the muscular valve at the bottom of the esophagus maintains its tone to prevent stomach contents from refluxing upward.
What It Detects
- A weak or frequently relaxing lower esophageal sphincter, which is the primary physical cause of acid reflux in most people with GERD
- Esophageal motility disorders conditions in which the coordinated muscle contractions that move food downward (peristalsis) are weak or absent, which can worsen reflux symptoms
- Achalasia a condition that can mimic GERD symptoms but requires different treatment
When it is used?
Esophageal manometry is not used as a test for the diagnosis of GERD by itself. The test is usually done to check for the normal functioning of the muscles of the esophagus prior to anti-reflux surgery, as the symptoms of the patient can become more severe in the presence of a motility disorder. It is also done in cases where the results of the pH monitoring test are unclear, and the doctor requires more information about the functioning of the esophagus.
What to Expect
A thin, flexible pressure-sensing tube is passed through the nose and guided into the esophagus. The patient swallows small sips of water while the tube records pressure measurements at multiple points along the esophagus. The procedure takes approximately 30 to 45 minutes and does not require sedation.
Upper GI Series (Barium Swallow)
What It Is
An upper GI series also called a barium swallow is an X-ray study in which the patient drinks a liquid contrast agent containing barium, which coats the lining of the esophagus, stomach, and upper small intestine to make them visible on X-ray imaging.
What It Detects
- Hiatal hernia the most common structural finding associated with GERD
- Esophageal strictures or narrowing caused by chronic acid damage
- Large reflux episodes visible as barium flowing back from the stomach into the esophagus during the X-ray
- Any structural abnormalities in the esophagus or stomach, which may be causing or contributing to the symptoms of reflux
Limitations
- The upper GI series is not considered to be a diagnostic test for GERD. Although the test may show the reflux of the barium liquid, it is not able to measure the frequency or the amount of the acid reflux, as the pH test can. A normal test result for the barium swallow does not necessarily mean the patient is not suffering from GERD, and an abnormal test showing the reflux of the barium liquid does not necessarily mean the patient has GERD.
Impedance-pH Monitoring
Impedance pH monitoring is the advanced form of the standard pH monitoring technique, which can monitor both acid and non-acid reflux episodes. In the standard pH monitoring technique, acid reflux with pH less than 4 is monitored, but there are also individuals with severe non-acid or weakly acidic reflux.
This test is particularly useful when a patient continues to have typical reflux symptoms despite adequate PPI therapy and standard pH monitoring shows normal acid levels. By identifying non-acid reflux as the cause of symptoms, the test helps doctors adjust treatment plans accordingly.
Comparison of GERD Diagnostic Tests
Conclusion
GERD is diagnosed through a process that includes symptom evaluation, response to anti-reflux medications, and targeted diagnostic testing. Endoscopy is used to evaluate damage and problems in the esophagus, ambulatory pH monitoring directly measures abnormal stomach acid exposure, esophageal manometry is used to evaluate muscle function pre-surgery, and an upper GI series is used to evaluate problems such as hiatal hernias. Anyone experiencing severe and persistent reflux symptoms should consider talking to a gastroenterologist to determine which diagnostic evaluation is best for them.
