Extension of the Thoracic Spine Sign

By Michael Prats, MD


Extension of the Thoracic Spine Sign: A New Sonographic Marker of Pleural Effusion

Journal of Ultrasound in Medicine September 2015 - Pubmed Link


Pleural effusions are common and ultrasound can find them. Point of care ultrasound may assist in diagnosing pleural effusion as the cause of a patient’s symptoms. The “extension of the thoracic spine” sign is an ultrasound sign that can identify pleural effusions not otherwise evident on ultrasound.


How sensitive and specific is the “spine sign”?


Inclusion: >18 yo + getting CT of abdomen or chest as part of work up (symptoms or chief complaint did not matter)

Exclusion: if consent could not be obtained, could not tolerate 45 degrees back, known pleural effusions, lung surgery, pleurodesis

Who did the ultrasounds?

3 emergency physicians - all had extensive experience with point-of-care sonography (2 had completed fellowship) who were not caring for the patient

Attended a lecture regarding how to diagnose pleural effusions with ultrasound


Single urban, academic, tertiary care center

Prospective convenience sample of ED patients, only enrolled when sonologist present

Calculated sensitivity and specificity


All patient enrolled received ultrasound and their CT.


Curvilinear probe

Patient supine, head elevated 45 degrees. Left and right lung bases in mid axillary line, looked for anechoic fluid collection and/or “spine sign”.

Spine sign = extension of the normally seen vertebral bodies superior to the diaphragm

Spine sign image


N = 41 patients = 82 hemithoraces

7 excluded (no images obtained)

Median time to complete scan: 3 minutes (max 13 minutes)

25% of population had pleural effusion on CT: 2 large, 12 small, 5 trace

Primary end point: Sensitivity 73.7%, Specificity 92.9%

If using spine sign + anechoic fluid: Sensitivity 78.9%, Specificity 87.5%

If exclude trace effusions: Sensitivity 92.9%, Specificity 92.9%


Broad inclusion criteria

Excluded patients in which we would like to know its accuracy (hx of pleural effusion, thoracic surgery, etc)

Small sample size, single center

Performed by skilled operators

Take Home Points

1. Thoracic spine sign alone is about 74% sensitive and 93% specific.

2. With regard to non-trace pleural effusions, thoracic spine sign is 93% sensitive and specific.

Our score

3 Probes

Cite this post as

Michael Prats, MD. Extension of the Thoracic Spine Sign . Ultrasound G.E.L. Podcast Blog. Published on April 12, 2016. Accessed on May 06, 2021. Available at https://www.ultrasoundgel.org/1.
Published on 04/12/16 08:53 PM
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