Westermark sign

Dr Dan J Bell and Dr Henry Knipe et al.

Westermark sign is a sign of pulmonary embolus (PE) seen on chest radiographs.

It is one of several described signs of pulmonary embolus on chest radiographs.

In one study (PIOPED) this sign was present on ~10% of chest x-rays of patients with confirmed PE 2

The theory behind the sign is either obstruction of the pulmonary artery or distal vasoconstriction in hypoxic lung 3

  • focal peripheral hyperlucency secondary to oligaemia 2-4
  • central pulmonary vessels may also be dilated 3

Nils Westermark (1892-1980) was a Swedish radiologist who first described this sign 5.

Chest x-ray
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Article information

rID: 29066
Systems: Vascular, Chest
Section: Signs
Tag: pe
Synonyms or Alternate Spellings:
  • Westermark's sign

Cases and figures

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    Case 1: left-sided
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    Case 2
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