Determination of atrial situs

Atrial situs refers to the relative position of the cardiac atria in relation to abdominal viscera and the midline.


Identification of atrial situs is an important initial step in the antenatal and postnatal diagnosis of cardiac structural and situs anomalies.

Radiographic features

Basic determination of situs relies on the ability to discriminate right and left atria, which depends on the morphologic characteristics of the atria and other features including the:

  • internal and external anatomy of the atrial appendages
  • connections of systemic and pulmonary vascular systems to the heart
  • anatomy of the interatrial septum

Out of these features, the most reliable method is the morphologic characteristic differences between the right and left atria.

Right atrium
Left atrium

Article information

rID: 31462
System: Cardiac
Section: Approach, Anatomy
Tag: pm, refs
Synonyms or Alternate Spellings:
  • Determining atrial situs

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