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

• A. To detect nonacid reflux events and correlate them with symptoms alongside acid events
• B. To measure gastric acid production
• C. To image the esophagus
• D. To assess esophageal motility

Answer: (A)

Impedance testing in esophageal reflux evaluation is focused on detecting reflux events regardless of their acidity by tracking bolus movement through the esophagus. By placing impedance sensors along the esophagus, the test senses changes in electrical resistance that occur when a liquid or gas bolus moves past each sensor. When you combine this with pH monitoring, you can classify reflux events as acidic or nonacid and see whether symptoms occur in temporal association with either type.

This approach is especially helpful because many patients have symptoms linked to nonacid reflux, which would be missed by pH testing alone. It provides a more complete picture of reflux burden and helps tailor management, such as identifying those who may not respond fully to acid-suppressive therapy because their symptoms are driven by nonacid reflux.

The other options don’t fit because measuring gastric acid production, imaging the esophagus, or assessing esophageal motility are accomplished by different tests (gastric function tests, radiologic imaging/endoscopy, and manometry, respectively).