Coccidioides antibody test of spinal fluid

Alternative names
Spinal fluid coccidioides antibody test; CSF coccidioides complement fixation

Definition
This test is used to determine if a fungus (Coccidioides immitis) is present in the cerebrospinal fluid (CSF).

How the test is performed
The test is usually performed on fluid obtained by lumbar puncture (spinal tap).

The cerebrospinal fluid is then analyzed in the lab. Complement fixation is a specific laboratory technique to determine the presence of antibodies formed when an individual has been exposed to an antigen (in this case, the antigen is Coccidioides immitis fungus).

How to prepare for the test
A consent form must be signed. You should be prepared to remain in the hospital for at least the 6 to 8 hours afterwards, and you should remain lying flat.

Infants and children:
The physical and psychological preparation you can provide for this or any test or procedure depends on your child’s age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child’s age:

     
  • infant test or procedure preparation (birth to 1 year)  
  • toddler test or procedure preparation (1 to 3 years)  
  • preschooler test or procedure preparation (3 to 6 years)  
  • schoolage test or procedure preparation (6 to 12 years)  
  • adolescent test or procedure preparation (12 to 18 years)

How the test will feel
The position may be uncomfortable, but it is imperative that you remain in the curled position to avoid moving the needle and possibly injuring the spinal cord.

The scrub will feel cold and wet. The anesthetic will sting or burn when first injected. There will be a hard pressure sensation when the needle is inserted, and there is usually some brief pain when the needle goes through the meninges. This pain should stop in a few seconds. Overall, discomfort is minimal to moderate. The entire procedure usually takes about 30 minutes but may take longer, the actual pressure measurements and fluid collection only takes a few minutes.

Why the test is performed
Complement fixation is the most sensitive test for the fungus coccidioides.

Normal Values
The presence of no fungus is normal.

What abnormal results mean
If the test is positive for fungus, the results indicate an active infection (see disseminated coccidioidomycosis).

What the risks are

     
  • risks of lumbar puncture include:       o hypersensitivity (allergic) reaction to the anesthetic       o discomfort during the test       o headache after the test       o bleeding into the spinal canal  
  • brain herniation (if performed on a person with increased intracranial pressure), resulting in brain damage and/or death  
  • damage to the spinal cord (particularly if the person moves during the test)

Special considerations
This test may also be done as a blood test, as well as on the CSF (see Coccidioides complement fixation). The CSF test means that there is an infection in the central nervous system, while the blood test just shows that there is infection somewhere in the body.

Johns Hopkins patient information

Last revised: December 7, 2012
by Sharon M. Smith, M.D.

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