Westermark sign

<h2 id="sensitivity-and-specificity">Sensitivity and specificity</h2>
<p>The Westermark sign, like <a href="/facts/Hampton%27s_hump/ryRvbq6d">Hampton's hump</a> (a wedge shaped, pleural based consolidation associated with <a href="/facts/Lung_infarction/HvCCqDz9">pulmonary infarction</a>), has a low <a href="/facts/Sensitivity_(test)/pzc9qfdz">sensitivity</a> (11%) and high <a href="/facts/Specificity_(statistics)/pzc9qfdz">specificity</a> (92%) for the diagnosis of pulmonary embolism.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a>  Put more simply, the Westermark sign is seldom seen in pulmonary embolism. When visible on a chest X-ray, the Positive Predictive Value is only 33%. That is, 33% of the time that Westermark sign is seen on Chest XRay does a pulmonary embolism actually exist <a href="https://litfl.com/westermark-sign/">[1]</a>.
</p>
<h2 id="etymology">Etymology</h2>
<p>It is named after <a href="/facts/Nils_Westermark/orNCSeat">Nils Westermark</a>, a Swedish radiologist.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a>
</p>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>Ray J (2003). "Westermark sign and suspected pulmonary embolism". Can J Cardiol. 19 (3): 317, author reply 317. PMID 12680403. <a href="/wiki/PMID_(identifier)" target="_blank">/wiki/PMID_(identifier)</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
<li id="fn:2"><p>Introduction to Chest Radiography. http://www.med-ed.virginia.edu/courses/rad/cxr/index.html <a href="http://www.med-ed.virginia.edu/courses/rad/cxr/index.html" target="_blank">http://www.med-ed.virginia.edu/courses/rad/cxr/index.html</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li>
<li id="fn:3"><p>Worsley D, Alavi A, Aronchick J, Chen J, Greenspan R, Ravin C (1993). "Chest radiographic findings in patients with acute pulmonary embolism: observations from the PIOPED Study". Radiology. 189 (1): 133–6. doi:10.1148/radiology.189.1.8372182. PMID 8372182. <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li>
<li id="fn:4"><p>Gurney J. CT: Diagnosis of Pulmonary Embolism. chestx-ray.com. Available at: 
http://www.chestx-ray.com/Lectures/PulmEmbLecture/PulmEmbolus.pdf. Accessed on: November 13, 2006. <a href="http://www.chestx-ray.com/Lectures/PulmEmbLecture/PulmEmbolus.pdf" target="_blank">http://www.chestx-ray.com/Lectures/PulmEmbLecture/PulmEmbolus.pdf</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li>
<li id="fn:5"><p>Dorland's Illustrated Medical Dictionary (32 ed.). Elsevier Health Sciences. 2011-06-09. p. 2080. ISBN 978-1455709854. <a href="978-1455709854" target="_blank">978-1455709854</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li>
</ol>

Westermark sign open-in-new

Westermark sign