A number of studies are used to evaluate people who have suspected GE reflux disease. Barium esophagram is the study that was traditionally used to evaluate GE reflux disease. It is easy and inexpensive to perform and when gross reflux is demonstrated is 85% specific. The shortcoming of this study lies in its sensitivity rate of 40%. Upper endoscopy is now the most frequently used study to evaluate suspected GE reflux disease. Indeed, when erosive esophagitis is identified by the endoscopist, specificity is in the 95% range. Many patients, however, who have GE reflux disease have no evident mucosal injury so the sensitivity of the study is in the 50-60% range.
The study that is now becoming accepted as the gold standard is the 24 hour ambulatory esophageal pH monitor. This study is performed by placing a pH probe with its tip 5 cm above the lower esophageal sphincter. The device is connected to a small monitor which is carried by the patient and records the pH during the course of the study. Additionally, the patient keeps a diary as to the timing of meals, recumbency and symptoms (heartburn, chest pain, wheezing or cough). The monitor is removed after 24 hours and then analyzed by a computer.
In evaluating the results of the 24 hour pH probe a number of factors are important to consider. The two most important factors are the fraction of time the pH is less than 4 (normally less than 4.5% of the time) and the symptom index which is calculated by dividing the number of symptoms with a pH less than 4 by the total number of symptoms during the course of the study. Generally patients whose symptoms are caused by GE reflux disease will have symptom indices in the 70% plus range.
Most patients with typical symptoms of GE reflux disease without complicating features such as weight loss or dysphagia can have a clinical diagnosis of GE reflux disease made without performing numerous diagnostic studies. If the patient fails to respond to appropriate medical management, or if surgical treatment is considered, then the diagnostic testing workup becomes important.