Definition of CSF coccidioides complement fixation:

CSF coccidioides complement fixation looks for antibodies to the fungus Coccidioides immitis in the cerebrospinal (CSF) fluid, the fluid surrounding the brain and spine.

How the test is performed:

Complement fixation is a specific laboratory technique that looks to see if the body has produced antibodies to a specific foreign substance (antigen) -- in this case Coccidioides immitis. If the antibodies are present, they stick, or "fix" themselves, to the antigen. That's why the test is called "fixation."

The spinal fluid needed to perform this test is usually obtained by lumbar puncture (spinal tap).

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 - 8 hours afterwards, and you should remain lying flat.

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.