Diagnosis and Testing
A thorough evaluation is necessary to prove that reflux is present. This evaluation may include a 24-hour pH test, esophageal motility test, upper endoscopy, upper GI series and a gastric emptying study. The only way to be 100% certain a person has GERD, is 24-hour pH monitoring.
The 24-hour pH test
A small, soft tube is passed through the nose into the esophagus to measure the amount of acid (pH) present in the esophagus. It usually records the pH in the upper esophagus (channel one) and the lower esophagus (channel two). It remains in place for 24 hours. Unfortunately, shorter periods of time do not give accurate measurements of reflux.
The tube is connected to a small box that is worn on the hip. The box has a button pushed whenever symptoms occur. This allows us to correlate symptoms with the amount of acid present in the esophagus.
In addition to measuring the pH in the esophagus, the device determines when episodes of reflux occur, how long they last and how severe they are. This information is used to calculate a composite score of the variables, called the DeMeester score. A value greater than 14 is abnormal and most patients with severe reflux have values in the 200 range.
It is important for patients to stop all anti-reflux medications for one week prior to undergoing a 24-hour pH, unless otherwise directed by a physician. Once the test is complete, patients can resume medications.
Esophageal motility study
The esophageal motility (manometry) test, measures the motion or contraction of the esophagus and the pressures it generates during contraction. This allows us to measure the pressure and length of the lower esophageal sphincter (LES) and how well the lower esophagus contracts. It also checks for the presence of high amplitude contractions (spasms) and high LES pressures (achalasia).
The test is important because it rules out other esophageal disorders that may mimic reflux or may alter the outcome of treatment. The test is also used to make sure that the esophagus has good distal contraction, so the patient is able to tolerate a surgical procedure should it be necessary. This test also checks for achalasia. Achalasia is a disorder of the LES, in which pressures are abnormally high and the LES does not relax.
How is an esophageal motility performed?
The test is similar to a 24-hour pH test, but lasts only about one to two hours. Once again, a small tube is passed via the nose into the esophagus. Pressures in the esophagus are measured from 5 sites (channels). Swallowing dry and wet determines not only the pressures present, but also the coordination of the contractions in the esophagus. As the upper esophagus contracts, the lower esophagus should relax.