This woman has presented with a cough, night sweats and progressive breathlessness. The most likely diagnosis is pseudochylothorax. Levels greater than 1000 IU/L are suggestive of empyema, malignancy or rheumatoid effusion. Haemorrhage and haemolysis associated with non-small cell lung cancer.Malignant melanoma (black colour caused by cells containing melanin pigment).The presence of food particles suggests oesophageal rupture.īlack pleural fluid is extremely rare, indicative of only a few diseases, including: Straw-coloured fluid with the distinctive smell of ammonia is indicative of urinothorax. Less common causes include tuberculosis (TB), aortic dissection, ruptured aortic aneurysm and malignancy. Grossly bloody fluid is usually associated with trauma. This is most often caused by lymphatic obstruction secondary to malignancy, chronic inflammation or thoracic duct injury by trauma or a surgical procedure. Colourįrankly purulent fluid indicates an empyema (an anaerobic empyema is likely if the fluid has a putrid odour).Ī milky fluid suggests chylothorax or pseudochylothorax. If a patient is thought to have a transudative pleural effusion but the Light’s Criteria suggest an exudate, the serum–pleural fluid protein gradient should be examined. The pleural fluid LDH value is greater than two-thirds of the upper limit of the normal serum value.The ratio of pleural fluid to serum LDH is greater than 0.6.

The ratio of pleural fluid to serum protein is greater than 0.5.

The fluid is considered an exudate if any of the following are present: Light’s criteria are more accurate for the diagnosis of exudative effusions. Protein 30 g/L (in patients with a normal serum protein level) Typical findings of normal pleural fluid are as follows:ĭiagnostic criteria for pleural effusion Transudate

CT thorax is more accurate for diagnosis and is better at characterising the size and location of a pleural effusion. If there is a large effusion then tracheal deviation may occur away from the effusion. Once the accumulated fluid is more than 300 mL, clinical signs such as decreased chest-wall movement, dullness to percussion and diminished breath sounds on the affected side of the chest become evident. At least 300mL of fluid must be present before chest X-rays can detect a pleural effusion. Reference ranges vary between labs, so always consult your local medical school or hospital guidelines.Ī pleural effusion is usually diagnosed on the basis of a chest X-ray. This guide provides a structured approach to the interpretation of pleural fluid results for specific diseases.

Color fluid app