What are the causes of pulmonary effusion?

Pleural effusion, also known as pulmonary effusion, has complex and varied causes, mainly including the following: 1. **Cardiac diseases**: Such as heart failure and cardiac valve disorders, which lead to poor blood circulation, increased intravascular pressure, and fluid leakage into lung tissues. 2. **Pulmonary infections**: Such as pneumonia and pulmonary tuberculosis, which cause lung tissue inflammation, increased vascular permeability, and fluid exudation. 3. **Injuries and iatrogenic causes**: Such as injuries resulting in esophageal rupture, thoracic duct rupture, and iatrogenic pleural effusion induced by medications. 4. **Other factors**: Systemic diseases such as connective tissue disorders and hypoalbuminemia can also lead to pulmonary effusion. The specific cause of pleural effusion must be determined based on the patient's clinical presentation and diagnostic findings to guide targeted treatment.