Pleural effusion has the following colors: yellowish, yellowish-green, flesh-washing color, milky white, black, brown, etc.1. Yellowish, it is yellowish in tuberculous pleurisy, other inflammatory exudation.2. Flesh-washing color, most of them are caused by metastasis of tumors.3. Bloody effusion, it is bleeding from thoracic cavity, pulmonary embolism, and tuberculous pleurisy, which will have such a bloody color.4. Milk-white, it is the color of celiac disease, cholesterol crystallization chest. chest, cholesterol crystallization chest caused.5, black, is the pleural effusion caused by aspergillosis.6, sauce color, is the color of pleural effusion caused by chronic hemothorax, amoebic liver abscess.