Investigation of choice for Zenker's diverticulum is:
"Once suspected, the diagnosis is established by a barium swallow. Endoscopy is usually difficult in the presence of a cricopharyngeal diverticulum; and potentially dangerous, owing to obstruction of the true esophageal lumen by the diverticulum and the attendant risk of diverticular perforation."- Schwartz
CECT
Endoscopy
Esophageal manometry
Barium Swallow