Which imaging modality is most useful to identify a pharyngoesophageal diverticulum in a patient with regurgitation of undigested food?

• A. Endoscopy
• B. Esophageal manometry
• C. 24-hour pH monitoring
• D. Barium esophagram (barium swallow)

Answer: (D)

A contrast-filled swallow study is the best way to identify a pharyngoesophageal diverticulum such as Zenker's because it directly images the pouch as contrast fills and outlines the outpouching at the pharyngoesophageal junction. This modality shows the diverticulum protruding behind the upper esophagus and can reveal retention of contrast inside the pouch, which explains regurgitation of undigested food. Endoscopy can visualize a diverticulum but isn’t as reliable for outlining its full anatomy and carries a risk of perforation when navigating around the pouch. Esophageal manometry and 24-hour pH monitoring assess function or acid exposure rather than anatomy, so they won’t mainly identify the diverticulum.