Clinical meaning
The clinician evaluating pericardial effusion must systematically determine the etiology, assess hemodynamic significance, and plan definitive management. Etiological workup is guided by clinical context: in developed countries, idiopathic/viral causes predominate (up to 50%), followed by malignancy (10-25%), autoimmune (5-15%), bacterial (1-5%), and post-procedural (5-10%). In developing countries and immunocompromised patients, tuberculosis is a leading cause. The Light criteria adapted for pericardial fluid classify effusions as transudative (heart failure, hypothyroidism, nephrotic syndrome) vs exudative (infection, malignancy, autoimmune). Cytology has sensitivity of only 60-90% for malignant effusions; pericardioscopy with biopsy increases diagnostic yield to 95%. Adenosine deaminase (ADA) above 40 U/L in pericardial fluid is highly suggestive of tuberculous pericarditis. The clinician must recognize special scenarios: purulent pericarditis (emergency requiring drainage plus IV antibiotics plus surgical washout), uremic pericarditis (responds to intensified dialysis), post-cardiac injury syndrome (inflammation after MI, surgery, or trauma, treated with NSAIDs plus colchicine), and effusive-constrictive pericarditis (tamponade that persists after drainage due to visceral pericardial constriction, requiring pericardiectomy). Management decisions include observation (small, stable, asymptomatic), medical therapy (anti-inflammatory for pericarditis), pericardiocentesis (tamponade or diagnostic), surgical drainage (purulent, recurrent, loculated), and pericardiectomy (constrictive or recurrent refractory).