Westermark sign

Pattern seen in radiologic examinations

Medical condition

Westermark sign

Differential diagnosis| hypovolemia

In chest radiography, the Westermark sign is a sign that represents a focus of oligemia (hypovolemia) (leading to collapse of vessel) seen distal to a pulmonary embolism (PE).[1] While the chest x-ray is normal in the majority of PE cases,[2] the Westermark sign is seen in 2% of patients.[3]

Essentially, this is a plain X-ray version of a filling defect as seen on computed tomography pulmonary arteriogram.

The sign results from a combination of:

1. the dilation of the pulmonary arteries proximal to the embolus and
2. the collapse of the distal vasculature creating the appearance of a sharp cut off on chest radiography.

## Sensitivity and specificity

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The Westermark sign, like Hampton's hump (a wedge shaped, pleural based consolidation associated with pulmonary infarction), has a low sensitivity (11%) and high specificity (92%) for the diagnosis of pulmonary embolism.[4] 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 [1].

## Etymology

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It is named after Nils Westermark, a Swedish radiologist.[5]

## References

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1. ^ Ray J (2003). "Westermark sign and suspected pulmonary embolism". Can J Cardiol. 19 (3): 317, author reply 317. PMID 12680403.
2. ^ Introduction to Chest Radiography. http://www.med-ed.virginia.edu/courses/rad/cxr/index.html
3. ^ 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.
4. ^ 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.
5. ^ Dorland's Illustrated Medical Dictionary (32 ed.). Elsevier Health Sciences. 2011-06-09. p. 2080\. ISBN 978-1455709854.

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Signs and symptoms relating to the respiratory system

Auscultation|

* Stethoscope
* Respiratory sounds
* Stridor
* Wheeze
* Crackles
* Rhonchi
* Stertor
* Squawk
* Pleural friction rub
* Fremitus
* Bronchophony
* Death rattle
* Elicited findings
* Percussion
* Pectoriloquy
* Whispered pectoriloquy
* Egophony

Breathing|

| Rate|

* Apnea
* Prematurity
* Dyspnea
* Hyperventilation
* Hypoventilation
* Hyperpnea
* Tachypnea
* Hypopnea
* Bradypnea

|

Pattern|

* Agonal respiration
* Biot's respiration
* Cheyne–Stokes respiration
* Kussmaul breathing
* Ataxic respiration

Other|

* Respiratory distress
* Respiratory arrest
* Orthopnea/Platypnea
* Trepopnea
* Aerophagia
* Asphyxia
* Breath holding
* Mouth breathing
* Snoring

Other|

* Chest pain
* In children
* Precordial catch syndrome
* Pleurisy
* Nail clubbing
* Cyanosis
* Cough
* Sputum
* Hemoptysis
* Epistaxis
* Silhouette sign
* Post-nasal drip
* Hiccup
* COPD
* Hoover's sign
* asthma
* Curschmann's spirals
* Charcot–Leyden crystals
* chronic bronchitis
* Reid index
* sarcoidosis
* Kveim test
* pulmonary embolism
* Hampton hump
* Westermark sign
* pulmonary edema
* Kerley lines
* Hamman's sign
* Golden S sign

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Radiologic signs

Cardiovascular|

* Aortic unfolding
* Dense artery sign
* Halo sign

Respiratory|

* Air crescent sign
* Deep sulcus sign
* Golden S sign
* Hampton hump
* Kerley lines
* Peribronchial cuffing
* Sail sign of the chest
* Silhouette sign
* Steeple sign
* Thumbprint sign
* Traction bronchiectasis
* Tree-in-bud sign
* Westermark sign

Urogenital|

* Canga's bead symptom

Musculoskeletal|

* Crescent sign
* Fabella sign
* Fat pad sign/Sail sign of the elbow
* Osteopathia striata

Gastrointestinal|

* Cupola sign
* Double bubble
* Endoexoenteric
* Football sign
* Hampton's line
* Hot quadrate sign
* Mumoli's sign
* Omental cake
* Pneumatosis intestinalis
* Rigler's sign
* Sentinel loop

Neurological|

*   * Hyperdense middle cerebral artery

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