Which type of chest radiography is more reliable in the detection of small pleural effusions?

Updated: Dec 28, 2018
  • Author: Kamran Boka, MD, MS; Chief Editor: Guy W Soo Hoo, MD, MPH  more...
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Lateral decubitus films more reliably detect smaller pleural effusions. Layering of an effusion on lateral decubitus films defines a freely flowing effusion and, if the layering fluid is 1 cm thick, indicates an effusion of greater than 200 mL that is amenable to thoracentesis. Failure of an effusion to layer on lateral decubitus films indicates the presence of loculated pleural fluid or some other etiology causing the increased pleural density. Note that decubitus films are almost never performed in those institutions with bedside ultrasonography. (See the image below.)

Left lateral decubitus film displaying freely laye Left lateral decubitus film displaying freely layering left-sided pleural effusion.

Also see Also see Pleural Effusion Imaging.

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