Pleural effusion can't find the cause. Urgent! Unknown cause left.

If pleural effusion is related to cardiogenic diseases, it cannot be detected by routine lung examination. Congestive heart failure and constrictive pericarditis will produce pleural effusion in the left lung. Tumors smaller than 3 cm in the lung cannot be detected by ordinary X-ray examination. CT or PET-CT is needed to detect them.