Normal CSF Color
Normal cerebrospinal fluid should be clear and colorless (crystal-clear), resembling water. 1, 2, 3
Normal Appearance Characteristics
- CSF is normally completely transparent with no turbidity or cloudiness 1
- The fluid should be free of any clotted material or debris 1
- In postmortem studies of living patients, approximately 15% of CSF samples obtained via standard lumbar puncture demonstrate this crystal-clear appearance 4
Pathological Color Changes and Their Significance
Xanthochromia (Yellow Discoloration)
- Indicates breakdown of red blood cells and presence of bilirubin in the CSF 5
- Seen in 75% of patients with intracerebral hemorrhage when combined with grossly bloody CSF 5
- Can also occur in hemorrhagic infarction, though less commonly 5
- Xanthochromia distinguishes true subarachnoid hemorrhage from traumatic tap, as it takes several hours for RBC breakdown to produce yellow discoloration
Grossly Bloody or Pink/Rose-Colored CSF
- Indicates presence of red blood cells, either from pathological bleeding or traumatic tap 5
- In intracerebral hemorrhage, 75% of patients have either grossly bloody or xanthochromic CSF 5
- In cerebral infarction without hemorrhagic conversion, CSF is never grossly bloody 5
- HSV encephalitis can produce hemorrhagic CSF with elevated red cell counts in approximately 50% of cases 6
Turbid or Cloudy CSF
- Suggests elevated white blood cell count, typically seen in bacterial meningitis 7
- Contrasts with the clear appearance typical of viral meningitis 7
- Can also indicate elevated protein levels or presence of microorganisms 1
Clinical Pitfalls to Avoid
- Do not assume bloody CSF is always from traumatic tap - obtain opening pressure, cell counts, and compare tube 1 versus tube 4 to differentiate 6
- Xanthochromia takes time to develop - early lumbar puncture after subarachnoid hemorrhage may show bloody but not yet xanthochromic fluid 5
- In postmortem samples, CSF color changes significantly with postmortem interval, showing various color spectra from clear to xanthochromic to rose 4
- Following traumatic tap, correct white cell counts by subtracting 1 WBC for every 7000 RBCs present 6