What's the Diagnosis? By Dr. Becca Fieles

A 61 yo F w/ PMH HTN, DM, CKD presents to the ED w 1 month of progressively worsening dyspnea, cough and fatigue. She also endorses lower extremity swelling for the past 1 week. She denies fever, chills, nausea or vomiting. A CXR is obtained and shown below. What's the diagnosis? (scroll down for answer) 



 Answer: Pleural Effusion 


  • Transudative vs Exudative effusions 

  • Transudative – caused by increased hydrostatic pressures and decreased plasma oncotic pressures (Congestive Heart Failure, Cirrhosis, Nephrotic syndrome) 

  • Exudative – caused by local processes resulting in increased capillary permeability and exudation of fluid, protein, cells (Pneumonia, Malignancy, Pulmonary Embolism, Viral Infection, Tuberculosis)

  • Chylous effusion – caused by traumatic or neoplastic damage to thoracic duct or superior vena cava syndrome 

  • Hemothorax – bloody pleural effusion, most often due to trauma but also can be a result of coagulopathy 

  • Empyema – pus in pleural space, often parapnuemonic 


-Can be asymptomatic

-Can cause dyspnea, pleuritic chest pain  (pain can be referred to the shoulder or to the abdomen)   

-Physical exam shows decreased breath sounds on side of effusion, dullness to percussion, absent tactile fremitus, rapid and shallow respirations.

Differential:  Effusion vs Pneumonia vs Lung cancer vs Anemia vs Congestive Heart Failure vs Pulmonary Embolism vs COPD 

Diagnosis:  -CXR: blunting of costophrenic angle

                    -Ultrasound, CT

                    -Pleural fluid analysis with protein, LDH, cell count and differential, Gram stain, bacterial cultures, glucose, TB fluid markers, amylase 

  • Light’s Criteria 

  • 1. Ratio of pleural fluid protein to total serum protein > 0.5 

  • 2. Ratio of pleural fluid LDH to total serum LDH > 0.6 

  • 3. Pleural fluid LDH is 2/3 or greater than the upper limit for serum LDH 

If any one criteria is positive, the pleural effusion is exudative 

Treatment: Thoracentesis or tube thoracostomy +/- thrombolytic or DNAse if loculations present, Treatment of underlying cause