What is the purpose of pH impedance testing in reflux evaluation?

• A. To measure gastric acid production.
• B. To detect both acid and nonacid reflux and assess reflux frequency, duration, and proximal extent.
• C. To assess gastric emptying.
• D. To visualize esophageal mucosa.

Answer: (B)

The main concept is that this test identifies all reflux events, not just the acidic ones, and records how often they occur, how long they last, and how far up the esophagus they reach. By using impedance sensors, the test detects the movement of a refluxed bolus through the esophagus—whether it’s acidic or not—while the pH sensor indicates when reflux is acidic. This combination lets you distinguish acid from nonacid reflux and to quantify the frequency, duration, and proximal extent of each event, often over a 24-hour period while the patient goes about daily life.

Choices that focus only on acid production, gastric emptying, or visualization of the esophagus don’t capture this full picture. Measuring gastric acid production looks at secretion, gastric emptying studies assess how quickly contents leave the stomach, and visualization of mucosa is done with endoscopy.