Spinal fluid samples are either clear or turbid. Some sources use the following rating system for turbid CSF specimens:

• 0 = crystal clear fluid
• 1+ = faintly cloudy, smoky, or hazy
• 2+ = turbidity clearly visible but newsprint read easily through tube
• 3+ = newsprint not easily read through tube
• 4+ = newsprint cannot be seen through the tube

Turbidity may be caused by leukocytes, erythrocytes, fungi, bacteria, amoebae, contrast media, or aspiration of epidural fat during puncture.

200 leukocytes/mm³ will cause slight turbidity (1+); increased numbers of WBCs will cause increased turbidity. At least 400 erythrocytes/mm3 are needed to produce 1+ turbidity.

Occasionally CSF will have an oily appearance due to the presence of substances remaining in the CSF after radiologic (x-ray) procedures have been performed.