Pleural Fluid Aspiration procedure (Thoracentesis)

What sample is needed for Pleural Fluid Analysis?

1. The sample is aspirated from the pleural cavity.

What are the indications for Pleural fluid aspiration (Thoracentesis)?

1. This may be diagnostic.
2. Or maybe therapeutic to relieve the pain and dyspnoea.
3. Gram and AFB stain may be done.
4. It is used for culture.
5. It can be used for the PCR for the diagnosis of tuberculosis.
6. It may be done in case of malignancy.
7. Autoimmune diseases like systemic lupus erythematosus (SLE).
8. Inflammation of the pancreas, like pancreatitis.
9. In the case of pneumonia.
10. Empyema (pus in the pleural space).

What are the contraindications for Pleural fluid aspiration?

1. Avoid in case of thrombocytopenia.
2. Avoid in patients with bleeding tendency.
3. In case the volume is too small.
4. If the patient has a bleeding tendency.
5. If there is a skin disease in the area of the puncture.
6. If the patient is on anticoagulant therapy.
7. There are chances for infection.
8. Chances of liver or spleen injury.

How will you define pleural fluid?

1. The pleural fluid is obtained from the pleural cavity, between the parietal pleural membrane lining the chest wall and the visceral pleural membrane covering the lungs.
2. Pleural fluid may be:
   1. Exudate is mostly due to infections or neoplastic processes.
   2. Other conditions like collagen diseases, trauma, pulmonary infarction, and drug hypersensitivity may cause exudate.
3. Transudate is due to congestive heart failure, nephrotic syndrome, hypoproteinemia, and cirrhosis.
4. The most common cause is congestive heart failure.

How will you define thoracentesis?

• It is the removal of the fluid or air from the pleural cavity.

Pleural Fluid Analysis: Pleural fluid aspiration procedure (Thoracentesis)

What is the gross appearance of Pleural Fluid in various diseases?

1. In the case of empyema, it has a foul odor and a thick and pus-like appearance.
2. Chylothorax fluid is opalescent and pearly fluid.
   1. The chylous fluid contains a high concentration of triglycerides and a positive Sudan III stain.
   2. Pseudochylous fluid contains a high concentration of cholesterol and cholesterol crystals.

What is the difference between chylous and pseudochylous pleural fluids?

1. How to differentiate hemothorax and hemorrhagic exudate:
   1. Advise hematocrit (Hct) on the pleural fluid:
      1. In the case of hemothorax = Hct is similar to the blood.
      2. In chronic membranous disease, fluid = Hct will be much lower.

What are the microscopic examination findings of pleural fluid?

1. Total cell count:  
2. The cell count >1000 /mL suggests exudate.
3. Polys indicate an acute inflammatory condition like pneumonia, early tuberculous effusion, and pulmonary infarction.
4. If >50% of white cells are lymphocytes, it indicates tuberculosis or neoplasm.
5. The presence of RBCs indicates neoplasm, intrathoracic bleeding, or malignancy.

What is the significance of the various cell types in the pleural fluids?

What are the biochemical findings of pleural fluid?

1. Protein: 
   1.  >3 g/dL indicates exudates.
   2. <3 g/dL indicates transudates.
   3. Albumin gradient is a better factor than total protein.
      1. Albumin gradient = Pleural albumin – serum albumin.
      2. A value 1.1 g/dL or more indicates transudate.
      3. Value <1.1 g/dL indicates exudate.
   4. Total protein ratio = Fluid total protein – serum total protein
      1. If the ratio is >0.5, it indicates exudate.
2. pH:
   1. Normal pH =  7.4
   2. <6.0 indicates an esophageal rupture and allows the influx of acid or gastric fluid from the stomach.
   3. >7.4 indicates malignancies.
   4. Pleural fluid pH <7.3 may indicate the need for chest tube drainage and antibiotics in case of pneumonia.
3. Glucose:
   1. The glucose level is like a serum glucose level.
   2. Glucose <60 mg/dL may be seen in:
      1. Tuberculosis.
      2. Malignancy.
      3. Rheumatoid arthritis.
      4. Empyema.
4. Amylase:
   1. This may be elevated in malignant tumors.
   2. It will be raised in case of pancreatitis, and this amylase may be the first to be raised in the pleural fluid.
   3. Rupture of the esophagus with leakage of salivary amylase.
5. Lactate dehydrogenase (LDH):
   1. Pleural fluid LDH / serum LDH if >0.6 is seen in the exudate.
6. Triglycerides:
   1. This is done to diagnose chylous pleural effusion.
   2. In the chylous fluid, triglycerides are >110 mg/dL.

What is the significance of the chemicals in the pleural fluids?

7. Carcinoembryonic antigen (CEA):
   1. CEA is raised in case of pleural effusion due to GIT malignancy.
   2. This may be raised in the case of breast carcinoma.
8. Exudate:
   1. Pleural fluid cholesterol >60 mg/dL.
   2. Pleural fluid cholesterol: serum cholesterol = >0.3
   3. Pleural fluid bilirubin: serum bilirubin = 0.6 or more.
9. Transudate:
   1. Proteins are <3 g/dL.

What is the microscopic examination of pleural fluid?

1. Cytology:
   1. This will be positive in 50 to 60% of the malignant pleural effusion.
   2. The most common site is the lungs and breast.
   3. The third common cause is lymphoma.
2. In the case of pleural fluid, you may see staphylococcus aureus, Enterobacteriaceae, anaerobes, and mycobacterium tuberculosis.
3. Advice:
   1. Gram stain.
   2. Culture.
   3. AFB stain.
4. Gram stain and culture:
   1. Advise gram stain before starting the antibiotics.
   2. Advise culture for tuberculosis, and this may take 4 to 6 weeks.
   3. Advice for fungal culture because this may cause pleural effusion.
5. Immunologic tests: It differentiates pleural effusion from the immunologic and non-inflammatory processes.
   1. The most common tests advised are an anti-nuclear antibody (ANA) and Rheumatoid factor.

 What are the normal Pleural fluid findings?

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