Investigations of Pleural effusion

This article is to discuss the investigations needed to diagnose a case of pleural effusion .
1. X-ray chest : Homogenous opacity with obliteration of costophrenic angle, rising to axilla.
2. P-A film may show no abnormality if there is less than 300 ml pleural fluid. A lateral decubitus film may help to differentiate free fluid from previous inflammatory adhesions.
3. Pleural biopsy for  Malignancy & T.B

4. Aspiration (Thoracentesis)  ---> Transudate or Exudate .

5. Diagnostic ultrasound can localize the effusion more accurately.

N.B.: When ordinary measures fail to establish a definitive diagnosis and needle biopsy of the pleura is negative, thoracotomy or the recent technique of video
assisted thoracoscopy (VATS) with exploration of the lung and biopsy of the involved areas of the pleura.


Other findings in pleural effusion fluid


1- Low  Glucose ---> TB or tumour (low) - Rheumatoid disease (very low)
2-High Amylase ---> Pancreatitis (It is typically left sided pleural effusion)
3- Low C3, C4  e.g. SLE
4- R.B.Cs High  : Malignancy, T.B
5- LDH ---> High   with exudate. (> 250 mg/dl).
6- Malignant Cells ---> Malignancy
7- Z.N. or PCR for T.B
8- PH < 7.2 with empyema.
9- Chylous effusion (milky white, rich in fat, clears on addition of ether and stained orange with sudan III.
10- Pleural fluid: serum protein ratio > 0.5 with exudates.
11- Pleural fluid: serum LDH ratio > 0.6 with exudates.

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