Westermark sign

While the chest x-ray is normal in the majority of PE cases, the Westermark sign is seen in 2% of patients.

Hampton's hump along with Westermark sign may aid in the diagnosis of pulmonary embolism, although they are rare and their sensitivities and interoperator reliabilities are low.

Chest X-rays in PE are rarely normal, but usually lack signs that suggest the diagnosis of PE (e.g. Westermark sign, Hampton's hump).

In chest radiography, the Westermark Sign, is a sign that represents a focus of oligemia (leading to collapse of vessel) seen distal to a pulmonary embolism (PE).