New diagnostic techniques for esophageal disorders.

Esophageal disorders are common in the general population and can be associated with significant morbidity. Several new diagnostic techniques for esophageal disorders have become available in recent years. These include capsule pH-metry, high-resolution manometry, impedance combined with either pH-metry or manometry, and high-frequency ultrasound. Capsule pH-metry is useful in children and in patients who cannot tolerate the conventional pH-metry catheter. It has the advantage of not interfering with a patient's usual meals and activities during the 24 h study. High-resolution manometry is easier to perform and interpret than conventional manometry. This has led to improved diagnosis of various esophageal motility disorders. Impedance measures the movement of liquid and gas in the esophagus. When combined with pH-metry, impedance can confirm that retrograde bolus movement (ie, reflux) is occurring while simultaneously measuring changes in pH levels. It has also highlighted the importance of weakly acidic reflux in patients who do not respond to proton pump inhibitors. Weakly acidic reflux cannot be diagnosed with pH-metry alone. Impedance combined with manometry can determine whether a manometric abnormality leads to abnormal bolus clearance. In the past, this was performed with fluoroscopy, yet impedance is equally effective and does not carry the risk of increased radiation exposure. High-frequency ultrasound is currently a research tool to image the esophageal wall, particularly the two muscle layers, in real time during swallows and at rest. It has broadened our understanding of the pathophysiology of esophageal motility disorders.