Fluid Analysis:- Part 2 – Fluid Analysis Parameters, Therapeutic Fluid Aspiration
Sample for Fluid Analysis
- The fluid for the analysis are:
- Ascitic fluid.
- Pleural fluid.
- Pericardial fluid.
- Amniotic fluid.
- Cerebrospinal fluid.
- Semen analysis.
- Cervical mucus test.
- Joint fluid (synovial fluid).
- Sweat chloride test.
- Urine analysis.
Indications for Fluid Analysis
- To diagnose the cause of the fluids.
- This could be therapeutic.
- To diagnose the diseases.
Precautions for Fluid Analysis
- The fluid analysis should be done immediately to prevent false results due to cellular or chemical deterioration.
- Follow precautions if there is a delay in the testing of fluid.
Pathophysiology of Fluids
- Effusions from the abdomen, pleura, pericardium, and joints are classified into exudate and transudate.
- Exudates are caused by inflammatory, infectious, or neoplastic diseases.
- Transudates are caused by venous congestion, hypoproteinemia, and fluid overload.
- Some of the fluids are analyzed to diagnose the disease, like sweat for cystic fibrosis.
Various Procedures to get fluids are:
- Lumbar puncture for CSF.
- Amniocentesis to get fluid from the uterus.
- Pericardiocentesis for pericardial fluid.
- Thoracentesis for pleural fluid.
- Paracentesis for the peritoneal fluid.
- Arthrocentesis for the fluid from the joints.
The fluid analysis includes:
- Gross appearance.
- Specific gravity
- Total protein
- LDH level.
- Total cell count.
- Microscopic examination for the differential count.
- Cytospin For the cytological examination.
- In the case of CSF, the glucose level is estimated.
- In some cases, AFB or Gram stain is done.
- Fluid analysis is to diagnose the etiology of fluid formation, or sometimes it may be therapeutic.
Therapeutic advantages of Fluid Analysis:
- Fluid aspirated from the pleural improves ventilation and oxygenation.
- Fluid from the Peritoneum relieves the pressure and ease of breathing and eating.
- Fluid aspirated from the joint relieves the pain and function.
- Fluid aspirated from the pericardial cavity improves diastolic filling and cardiac output.
Difference between various fluids:
|Appearance||cloudy||clear||cloudy to milky|
|Color||variable||pale yellow||pale yellow to milky|
|DLC||poly → MN cell||lympho||poly → MN cells|
|Triglycerides||<60 mg/dL||<60 mg/dL||>110 mg/dL|
|Fluid protein/serum TP||>0.5||<0.5||>o.5|
|Fluid LDH/serum LDH||>0.6||<0.6||>0.6|
TP = Total protein
MN = Mononuclear cells.
Comparison of Transudate and Exudate:
|Parameter (Characteristic features)||Transudate||Exudate|
Yellow (inflammatory) Red (hemorrhage)
Brown (bilirubin) or cloudy
|Protein||<3 g/dL||>3 g/dL|
|Fluid: serum protein ratio||<0.5||>0.5|
|Fluid: LD ratio||<0.6||>0.6|
|LDH||Normal <200 IU/L||Increased >200 IU/L|
|Glucose||Normal (equal to serum level)||Less or equal to serum|
|Pleural fluid cholesterol||<60 mg/dL||>60 mg/dL|
|Pleural fluid: serum cholesterol ratio||<0.3||>0.3|
|Pleural fluid: bilirubin ratio||<0.6||>0.6|
|Fibrinogen||No clot||Clots are seen|
|Spontaneous clotting||Negative||May see clot formation|
|Cell count||300 to 1000 /cmm||>1000 /cmm|
|WBCs||Few lymphocytes||Many polys >25%|
|Differential||Mononuclear cells predominate
- Please see more details in fluid part 3.