Anechoic pleural effusion (ultrasound)

Case contributed by Dr David Carroll


ESRD on dialysis, known atelectasis and right pleural effusion.

Patient Data

Age: 40
Gender: Male

Cineloop: Right longitudinal subcostal scan, liver and overlying hemidiaphragm visualized. Loss of normal mirror and curtain signs with crisp diaphragmatic surface and extension of the thoracic spine cephalad to costophrenic sulcus. Space above hemidiaphragm anechoic, with no plankton sign or septations, layers dependently.

Diagnosis: small to moderate right sided pleural effusion, adjacent lung atelectatic. 

Smooth lung line visualized within anechoic space bordered by hemidiaphragm and spine, underlying lung lacks typical aeration artifacts and is of greater echogenicity than usual, dynamic respiratory excursion. 1-2 sub B-lines briefly visualized, no air/fluid bronchograms.

First image demonstrates the spine sign, with the translucent red line demarcating the anterior surface of the vertebral bodies.

Second image shows the sonographic landmarks for identification of the costophrenic sulcus (hemidiaphragm, thoracic spine) which is made visible by (asterisk) anechoic fluid.

Case Discussion

This case features a patient with a history of end-stage renal disease with a small-moderate, asymptomatic pleural effusion and probable adjacent atelectasis, found incidentally but illustrating some of the classic ultrasound findings and signs in a pleural effusion. Visualization of the thoracic spine sign is highly suggestive of a pleural effusion, with the following sonomorphologic hallmarks further increasing diagnostic confidence 1

  • the quad sign defines the boundaries of a pleural effusion
    • laterally, two anechoic posterior rib shadows, superficially the parietal pleura, and the visceral pleura (or "lung line") is found deep
  • the sinusoid sign is an inspiratory decrease in the size of the effusion

This is a free-flowing, simple effusion, evidenced by its dependent location, anechoic and homogenous nature, lack of septations, and absence of the plankton sign.

Learning points:


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Case information

rID: 65725
Published: 20th Jan 2019
Last edited: 14th Aug 2019
System: Chest
Tag: lung, pocus
Inclusion in quiz mode: Included
Institution: St. George's University

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