Pleural effusion (ultrasound)

Case contributed by Dr David Carroll


Slowly progressive dyspnoea.

Patient Data

Age: 80 years
Gender: Female

Pleural effusion initially identified with transducer in standard cephalo-caudad orientation. Of note, screen orientation was mistakenly reversed from usual bedside sonography convention.

Transducer is rotated 90 degrees, now perpendicular to the long axis of the patient's body. Effusion remains visible as an anechoic, crescentic area surrounding a prominent and heterogenously hyperechoic triangular protrusion representing atelectatic lung (plausible etiology compressive atelectasis given size of effusion)

The still image depicts how one would then calculate interpleural distance in keeping with a Balick formula calculation of pleural effusion volume. 

Case Discussion

This case details how one would calculate a pleural fluid volume in a supine patient using the Balick formula. In the above orientation, the cine-loop was paused at maximal inspiration. 

The distance is measured between the visceral pleura, adherant to the atelectatic lung, and the parietal pleura, adherent to the (in this case, dorsolateral) chest wall. Given a resultant interpleural distance of 3.8cm, the Balick formula is used to estimate the volume as follows:

Volume (mL) = 38mm x 20 = 760mL 1

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Case information

rID: 63393
Published: 1st Oct 2018
Last edited: 14th Aug 2019
System: Chest
Inclusion in quiz mode: Excluded
Institution: St. George's University

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