Lower esophageal rings are classified into two primary types. The A-ring is a thick, muscular ring found approximately 2 cm above the squamocolumnar junction. It marks the upper border of the lower esophageal sphincter (Fig. 5.1). Muscular A-rings are exceedingly rare. Although many clinicians consider them a variant of normal esophageal anatomy, they have been reported to cause dysphagia (1,2 and 3). Because the constriction caused by A-rings is secondary to muscular hypertrophy and not stricture formation, dilation is seldom successful at relieving the dysphagia. Botulinum toxin type A injections into the muscular ring have been shown to be beneficial but may result in a significant increase in reflux (3). Whereas the A-ring is muscular, the B-ring is a thin, annular membranous ring of mucosa associated with submucosal fibrosis at the gastroesophageal junction.

The B-ring is the classic Schatzki’s ring. Schatzki’s rings are the most common cause of solid food dysphagia in adults. They are seen in up to 14% of routine barium swallow examinations (1,2). The majority of esophageal rings are found incidentally and are of little significance. Although the exact etiology of Schatzki’s rings is uncertain, it may be related to chronic gastroesophageal reflux disease. They are usually found at the squamocolumnar junction and are almost always associated with a hiatal hernia (Fig. 5.2). Squamous esophageal mucosa is seen on the proximal and gastric columnar mucosa on the distal surface of the ring. Gastroesophageal reflux disease should be considered in all patients, and ambulatory pH monitoring or empiric antireflux therapy should be performed in select patients (4,5). Schatzki’s rings, when measured radiographically, tend to be symptomatic if the opening is <13 mm. Those that leave an 18- to 20-mm lumen are nearly always asymptomatic. Dilation of the B-ring is successful in relieving the dysphagia. This may be accomplished by mechanical dilation (bougienage) or disruption by pneumatic balloons using endoscopy or fluoroscopy. Care should always be taken when evaluating a patient using transnasal esophagoscopy because the smaller caliber endoscope may allow the examiner to miss esophageal rings, as well as mild strictures. In addition, the power of the air insufflator is less than the standard gastroenterology esophagoscope, and this limits our ability to distend the esophagus and visualize some rings and webs.