What is being tested?
Cerebrospinal fluid (CSF) is normally found only within the brain and the spinal canal. If you suffer an injury which causes a tear in the membranes covering the brain and spine, CSF may leak out. This may sometimes cause watery fluid to drip from either the nose or the ear (rhinorrhoea or otorrhoea). Distinguishing CSF from other watery discharge involves looking for the presence of something which would normally only be found in CSF. Tau protein is beta 2 transferrin. This form of transferrin is present in CSF but not usually found in blood, nasal secretions, or other body fluids. The suspected sample should be examined along with a serum sample to confirm results.

How is the sample collected for testing?
The suspicious watery discharge will be collected into a plain plastic tube. A sample of blood will also be taken from a vein in your arm at the same time.