Azygo-esophageal recess

The azygo-esophageal recess (also known as the line/interface) (AER) is a prevertebral space formed by the interface of the posteromedial segments of the right lower lobe and the azygos vein and esophagus . The AER extends from the azygos arch to the aortic hiatus and has the following borders :

• anteromedially: esophagus, azygos vein, left atrium
• posteriorly: vertebral column
• inferiorly: right hemidiaphragm
• superiorly: continuous with the subcarinal space

Radiological appearance

Plain radiograph

• appears as a straight stripe running from the azygos arch to the level of the right hemidiaphram although it can normally deviate
  • an upper third rightward convexity may be normal in children and young adults
  • middle third may slightly leftward convex relative to the right lung near the hilum
  • lower third is usually straight

Related pathology

Deviation of the AER can be due to disease in the middle or posterior mediastinum.