Westermark sign is sign of PE on CXR


There are two findings:

  • enlargement of pulmonary artery
  • oligemia: collapse of distal pulmonary arteries due to hypoxic vasoconstriction distal to obstruction leading to loss of blood volume and increased lucency. 1

Enlargement of R PA:

Left oligemia:

Footnotes

  1. https://radiopaedia.org/articles/westermark-sign-1?lang=us