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Question 4#

In regard to the halo test, a positive indicator for cerebrospinal fluid (CFS) when tinged with blood will show the following when dropped on an absorbent tissue:

a. A single ring with a darker center spot containing blood components surrounded by a light halo of CFS
b. A double ring with a darker center spot containing blood components surrounded by a light halo of CFS
c. A single ring with a lighter center spot containing CFS surrounded by a darker halo of blood components
d. A double ring with a lighter center spot containing CFS surrounded by a darker halo of blood components

Correct Answer is B

Comment:

Copious clear drainage from the nose or ear makes the diagnosis of cerebrospinal fluid ( CSF) leakage obvious. Often, however, the drainage may be discolored with blood or small in volume if some drains into the throat. The halo test can help differentiate. Allow a drop of the fluid to fall on an absorbent surface such as a facial tissue. If blood is mixed with CSF, the drop will form a double ring, with a darker center spot containing blood components surrounded by a light halo of CSF. If this test is indeterminate, the fluid can be sent for beta-2 transferrin testing, a carbohydrate-free isoform of transferrin exclusively found in the CSF.