Table 4. Classification of esophageal diverticula regarding the size of the diverticular sac van Overbeek (44) and Verdonck and Morton (10) classification.

Grade (size of the diverticular sac)	van Overbeek classification	Verdonck and Morton classification
Grade I	The maximum diameter of the height of a thoracic vertebra	Diverticulum smaller than 2 cm
Grade II	Maximum diameter 1–3 thoracic vertebral bodies	Diverticulum between 2–4 cm
Grade III	Maximum diameter over 3 thoracic vertebrae	Diverticulum over 4 cm