How is pulmonary effusion caused?

Pulmonary effusion, medically termed pleural effusion, has complex and diverse causes, mainly including the following: 1. Cardiac factors: Conditions such as heart failure and heart valve disease can obstruct blood circulation, impair venous return, increase intravascular pressure, and cause fluid to leak into lung tissues, forming effusion. 2. Pulmonary infection: Infections such as pneumonia and tuberculosis can cause lung tissue inflammation, increased vascular permeability, and excessive fluid leakage from blood vessels, leading to fluid accumulation in the lungs. 3. Pulmonary diseases: Conditions such as lung cancer, pulmonary embolism, and pulmonary vasculitis can damage lung blood vessels or block lymphatic drainage, preventing normal fluid clearance and leading to fluid accumulation. 4. Trauma: Injuries such as pulmonary contusion and esophageal rupture can cause lung vessel damage or increased fluid accumulation within the pleural cavity.