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Introduction ⬇

Normal CSF is clear, with the appearance and viscosity of water. Abnormal CSF may appear hazy, cloudy, smoky, or bloody. Clotting of CSF is abnormal and indicates increased protein or fibrinogen levels.

The initial appearance of CSF can provide various types of diagnostic information. Inflammatory diseases, hemorrhage, tumors, and trauma produce elevated cell counts and corresponding changes in appearance.

Normal Findings ⬆ ⬇

Clear and colorless

Procedure ⬆ ⬇

  1. A lumbar puncture is performed (see Lumbar Puncture [Spinal Tap]).

  2. Compare the CSF with a test tube of distilled water held against a white background. If there is no turbidity, newsprint can be read through normal CSF in the tube.

Clinical Implications ⬆ ⬇

  1. Abnormal appearance (Table 5.3)—causes and indications:

    1. Blood in CSF can be due to hemorrhage or result from trauma from the lumbar puncture. If blood in CSF is caused by subarachnoid or cerebral hemorrhage, the blood is evenly mixed in all three tubes. Table 5.4 describes differentiation of bloody spinal tap from cerebral hemorrhage. Clear CSF fluid does not rule out intracranial hemorrhage.

    2. Turbidity is graded from 1+ (slightly cloudy) to 4+ (very cloudy) and may be caused by the following conditions:

      1. Leukocytes (pleocytosis [i.e., an increase in the number of cells—in this case, white blood cells (WBCs)—which is referred to as leukocytosis])

      2. Erythrocytes

      3. Microorganisms such as fungi and amebae

      4. Protein

      5. Aspirated epidural fat (pale pink to dark yellow)

      6. Contrast media

    3. Xanthochromia (pale pink to dark yellow) can be caused by the following conditions:

      1. Oxyhemoglobin from lysed red blood cells (RBCs) present in CSF before lumbar puncture

      2. Methemoglobin (iron in the heme group of the hemoglobin molecule is in the Fe3+, not the Fe2+, state)

      3. Bilirubin (>6 mg/dL or >103 μmol/L) (breakdown product of normal heme catabolism)

      4. Increased protein (>150 mg/dL or >1500 mg/L)

      5. Melanin (meningeal melanocarcinoma)

      6. Carotene (systemic carotenemia)

      7. Prior bleeding within 2–36 hours (e.g., traumatic puncture >72 hours before)

    4. Yellow color (bilirubin, >10 mg/dL or >171 μmol/L) due to a prior hemorrhage (10 hours to 4 weeks before)

Clinical Alert

  1. Spinal fluid should be cultured for bacteria, fungi, and tuberculosis. In children, Haemophilus influenzae type B is the most common cause of bacterial meningitis; in adults, the most common bacterial pathogens for meningitis are meningococci and pneumococci.

  2. Spinal fluid with any degree of cloudiness should be treated with extreme care because this could be an indication of contagious disease.

Interventions ⬆ ⬇

Pretest Patient Care

  1. Observations of color and appearance of CSF are always noted.

  2. Follow pretest patient care for lumbar puncture (see Lumbar Puncture [Spinal Tap]).

  3. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Recognize abnormal color and presence of turbidity and monitor patient appropriately.

  2. Follow posttest patient care for lumbar puncture (see Lumbar Puncture [Spinal Tap]).

  3. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Interfering Factors ⬆

  1. CSF can look xanthochromic (yellow discoloration) from contamination with methylate used to disinfect the skin.

  2. If the blood in the specimen is due to a traumatic spinal tap (which occurs in 10%–30% of cases), the CSF in the third tube should be clearer than that in tube 1 or 2; a traumatic tap makes interpretation of results very difficult to impossible.