Hydrothorax

Hydrothorax is the accumulation of fluid within the pleural cavity, or pleural effusion, usually consisting of serous fluid. It can be transudative or exudative depending on the underlying process.

Transudative hydrothorax reflects systemic factors that disrupt fluid balance, such as increased hydrostatic pressure or decreased oncotic pressure. Exudative hydrothorax results from inflammation or malignancy that increases pleural membrane permeability.

Causes include heart failure, cirrhosis with ascites (hepatic hydrothorax), nephrotic syndrome, and other states causing poor oncotic pressure or high hydrostatic pressure; infections, malignancy, pulmonary embolism, and pancreatitis can cause exudative hydrothorax. Hepatic hydrothorax is commonly right-sided and results from movement of ascitic fluid through diaphragmatic defects.

Clinical features are mainly dyspnea; pleuritic pain may occur. Exam may reveal reduced breath sounds, dullness to percussion, and decreased fremitus on the affected side.

Diagnosis relies on imaging (chest X-ray, ultrasound, or CT) to confirm the effusion, and analysis of pleural fluid obtained by thoracentesis. Light's criteria distinguish transudate from exudate. In hepatic hydrothorax, the fluid is typically transudative.

Management depends on cause and symptoms. Small, asymptomatic effusions may be observed; diuretics and dietary sodium restriction for transudates; therapeutic thoracentesis for relief; refractory cases may require chest tube drainage, pleurodesis, transjugular intrahepatic portosystemic shunt (TIPS), or liver transplantation.

Prognosis depends on the underlying disease; hepatic hydrothorax often indicates advanced liver disease.