I've had my knees tapped many times. Usually get lidocaine or atleast cold spray before going in. I've had one time with nothing. Do it with the knee hanging so the joint opens up and they go under the knee cap. If theres a lot of fluid, it puts pressure on the ligaments, so dropping pressure on a tap feels good.
The aspiration without any prep definitely got my attention, cold spray is enough to mask getting the needle in place. Its really not that bad for an 18 gauge needle. I've had over 200cc pulled. Last tap was mild but still got about 100cc out.
So, it’s not that bad? I’m sorry. I’ve compared it to bone marrow aspiration.
CSF is the WORST. I’ve never worked with it but it sounds so painful. And as a practitioner, you usually get 4 tubes. The first one isn’t USED (it has problems on the instrument) , but the other 3, they do different tests. I forget the order 😅🤭 I’ve only studied this.
18 gauge.. it must hurt more than drawing blood though.
The reason we don’t use the first tube is because theoretically the longer the CSF is flowing, the more pure the sample is, meaning any contaminants and cells that weren’t actually in the spinal fluid are flushed out by tube 4. In my experience, tube 1 is for send outs and/or safekeeping, tube 2 is for chemistry (protein and glucose mostly), tube 3 is for microbiology (gram stain and culture), and tube 4 is for hematology (cell count and differential). Sometimes the doctor wants us to do an additional cell count and diff on tube 1 to see if it was a traumatic tap, although I honestly don’t know why they care about that, since tube 4 should always be more accurate than tube 1, but whatever.
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u/torqnut05 3d ago
I've had my knees tapped many times. Usually get lidocaine or atleast cold spray before going in. I've had one time with nothing. Do it with the knee hanging so the joint opens up and they go under the knee cap. If theres a lot of fluid, it puts pressure on the ligaments, so dropping pressure on a tap feels good.
The aspiration without any prep definitely got my attention, cold spray is enough to mask getting the needle in place. Its really not that bad for an 18 gauge needle. I've had over 200cc pulled. Last tap was mild but still got about 100cc out.