Here is an example of bilateral pleural effusions. Note that the fluid appears reddish, because there has been hemorrhage into the effusion. This is a serosanguinous effusion.

• 胸膜腔积液的源于浆液性渗出、血胸、血性浆液。此种积液少见。如果在胸膜腔脓性渗出物聚积称为脓胸。