Figure 5 - Radiograph of a patient with a small axial hiatal hernia (case 2).

A prominent B ring is evident, but no A ring. The B ring occurs at the squamocolumnar junction and, when subtle, is referred to as the transverse mucosal fold. In instances such as this where there is marked compromise of the esophageal lumen, the B ring is referred to as a Schatzki ring and is a frequent cause of episodic solid food dysphagia. When a B ring is evident, the criterion for defining the hiatus hernia is a separation of 2 cm between the B ring and the diaphragmatic hiatus. (Source: Kahrilas and Pandolfino,⁷⁵ with permission.)