Gastroesophageal Reflux Disease (GERD) is a chronic condition defined by the persistent backflow of stomach contents into the esophagus. While mild, occasional heartburn is common, persistent symptoms require medical investigation to confirm the diagnosis, assess severity, and rule out complications. The diagnostic process begins with a detailed review of the patient’s medical history and symptoms.
Most people with classic symptoms like heartburn and regurgitation do not initially undergo specialized testing. Instead, doctors often start with an empirical trial of medication, typically a high-dose Proton Pump Inhibitor (PPI), which works by reducing the amount of acid produced by the stomach. The American College of Gastroenterology (ACG) recommends an eight-week trial of a daily PPI before a meal for patients with classic symptoms and no alarm signs.
If the patient’s symptoms significantly improve or resolve entirely during this trial, GERD is often diagnosed, and further testing may be unnecessary. This positive response to the PPI trial acts as a strong indicator that acid reflux is the cause of the discomfort. However, this approach has limitations; the sensitivity of a PPI trial for diagnosing GERD is estimated to be around 78%.
Specialized testing becomes necessary when the empirical PPI trial fails to resolve symptoms, or if the patient presents with atypical or severe warning signs. These “alarm symptoms” include difficulty swallowing, unexplained weight loss, gastrointestinal bleeding, or persistent vomiting. Objective diagnostic tests are required in these cases, or for patients with chest pain confirmed not to be cardiac-related, to definitively determine the cause and guide the next steps.
Visualizing the Upper Digestive Tract
When the initial assessment suggests a need for physical examination, doctors use visual and imaging procedures to look for structural issues or damage caused by acid. The most common and informative visual test is an Upper Endoscopy, also known as Esophagogastroduodenoscopy (EGD). The procedure involves inserting a thin, flexible tube equipped with a camera, called an endoscope, through the mouth, down the esophagus, into the stomach, and the beginning of the small intestine.
The primary purpose of an EGD is to visually inspect the lining of the upper gastrointestinal tract for signs of reflux-related injury. Doctors look for inflammation and erosions, collectively known as erosive esophagitis. The procedure also allows for the identification of complications such as esophageal strictures (narrowings of the tube) or ulcers.
A particularly important finding during endoscopy is Barrett’s Esophagus, a condition where the tissue lining the esophagus changes, increasing the risk of esophageal cancer. The endoscope is also equipped to take small tissue samples, or biopsies, which are then examined under a microscope. The procedure can also detect a hiatal hernia, where a portion of the stomach protrudes up through the diaphragm, contributing to GERD.
Another structural imaging technique is the Barium Swallow (Upper GI Series). The patient drinks a liquid containing barium, a substance that coats the digestive tract and makes it visible on an X-ray. While not typically used solely to diagnose GERD, the test helps visualize the shape of the esophagus and stomach, and watch the movement of the barium. This test is useful for identifying large hiatal hernias or significant strictures that may be impairing swallowing.
Measuring Acid Exposure and Muscle Function
For patients whose symptoms persist despite medication or whose diagnosis remains unclear after endoscopy, testing shifts to measuring the physiological function of the esophagus. These functional tests objectively quantify the amount of reflux occurring and assess the working condition of the esophageal muscles. Ambulatory pH Monitoring measures the frequency and duration of acid exposure in the esophagus.
The standard method is often the wireless pH capsule. The capsule is temporarily attached to the wall of the lower esophagus, usually during an endoscopy. For 48 hours, or sometimes longer, the capsule wirelessly transmits data on the pH levels to a small receiver worn by the patient.
A diagnosis of GERD is confirmed if the total acid exposure time in the esophagus is greater than a certain percentage over the monitoring period. The patient keeps a diary, noting when they eat, sleep, and experience symptoms, allowing doctors to correlate symptoms with actual reflux episodes. Another form is pH-impedance monitoring, which uses a thin catheter placed through the nose to detect non-acidic reflux, important for patients taking acid-suppressing medication.
Another test is Esophageal Manometry, which measures the pressure and coordinated movement of the esophagus. This test uses a pressure-sensitive catheter passed through the nose and into the stomach. As the patient swallows small amounts of water, the sensors measure the strength, speed, and pattern of muscle contractions, known as peristalsis.
Manometry also evaluates the function of the Lower Esophageal Sphincter (LES), the ring of muscle that acts as a valve between the esophagus and the stomach. Weakness or improper relaxation of the LES is a common cause of reflux. This test is often performed before anti-reflux surgery to ensure the esophagus is capable of proper movement and to rule out other motility disorders that can mimic GERD symptoms.