Azygo-esophageal recess

Last revised by Dr Daniel J Bell on 11 Aug 2018

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 1-3. The AER extends from the azygos arch to the aortic hiatus and has the following borders 1,2:

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 1-3
    • 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. 

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Cases and figures

  • Case 1: Azygo-esophageal recess on chest x-ray
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  • Figure 1: annotated chest x-ray
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