Ascites
the American Association for the Study of Liver Diseases recommends:
- Cell count and differential (especially polymorphonuclear leukocyte count)
- Total protein
- Albumin (to calculate the serum-ascites albumin gradient, SAAG)
- Culture (ideally inoculated into blood culture bottles at the bedside)
Additional tests may include glucose, lactate dehydrogenase (LDH), amylase, triglycerides, cytology, and adenosine deaminase (ADA) depending on clinical suspicion (e.g., malignancy, tuberculosis, pancreatic disease).
Pleural Fluid
- Cell count and differential
- Total protein and LDH (for Light’s criteria to distinguish exudate vs. transudate)
- Glucose
- pH
- Gram stain and culture
- Cytology (if malignancy is suspected)
Additional tests may include ADA (for tuberculosis), triglycerides (for chylothorax), and cholesterol.
CSF
- Cell count and differential
- Protein
- Glucose (with concurrent serum glucose)
- Gram stain and culture
- Opening pressure
Additional tests may include lactate, PCR for pathogens, cytology, oligoclonal bands, and specific antigen/antibody tests depending on the clinical scenario.
Synovial Fluid
- Cell count and differential
- Crystals
- Gram stain and culture