Hmmmm...

https://youtu.be/c_81VqY3G...

Why do doctors take spinal fluid for analysis? For example, to diagnose multiple sclerosis.
This is a real question.

Idk, yrs ago Nana had Pseudotumor cerebri, a brain condition, and they had to pull spinal fluid out periodically because I was making too much of it and to test it.
Their tests revealed the diagnosis but not the cause. No one knows the cause.
That is a good question tho.
What do they get out of testing spinal fluid they can't get from their normal blood tests?

And what do they do with it? Do they take more than they need and utilize it in some other way?
It seems a pretty sacred fluid.

Idk, what I had they said was pretty rare. Idk if there are other diseases that require it.

As mentioned in the other response, they're looking for evidence of bacterial vs. viral meningitis. Symptoms of the two variants are similar, apparently necessitating testing for presence of bacteria.

Meningitis was very painful, but that 3rd spinal tap really messed me up for a month or more. Couldn't sit or stand for a long time afterwards due to the pain (from lack of fluid?).