Which of the following statements about Schatzki's ring is correct?

B. Dysphagia occurs when the ring diameter is 13 mm. or less.

DISCUSSION: Schatzki's ring is seen radiographically as an annular weblike constriction at the esophagogastric junction in a patient with a sliding hiatalhernia. It represents prominence of the esophagogastric junction with slight submucosal fibrosis but not true panmural fibrotic reflux stricture. Intermittent dysphagia may occur when the ring size is 20 mm. or less, but dysphagia is almost invariable when the ring measures 13 mm. or less. Schatzki's ring occurs precisely at the squamocolumnar epithelial junction. It is indicative of the presence of a hiatal hernia but not of gastroesophageal reflux or esophagitis. An asymptomatic Schatzki's ring requires no therapy per se. Patients with refractory severe reflux symptoms after dilation therapy are candidates for antireflux surgery.