Bloody Tap?

[brainfailure]

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How do you tell between a bloody/traumatic tap and SAH? I had this guy with a new headache that had lasted four wks and tapped him twice yesterday and I got frank blood that would not clear twice. I did that thing where you blot the fluid on the sterile gauze and it did not produce a "halo". The guy was big and he had scoliosis, so i figured I had missed off the midline a little and got into vasculature. After two attempts, the pt did not want any more attempts even under ultrasound. By that time, the pt had a negative CT and his pain was totally gone after Compazine, so i felt safe discharging him. Now reflecting back, could it have been frank blood in the CSF from hemorrhage that was missed on CT. Is it possible to have a blled so big that you get blood in the CSF but miss it on CT? I always thought the ones that you miss on CT but catch on LP were microscopic blood or blood tinged or xanthrochromic, not frank blood. Is that right?

 

[Pinner Doc]

How do you tell between a bloody/traumatic tap and SAH? I had this guy with a new headache that had lasted four wks and tapped him twice yesterday and I got frank blood that would not clear twice. I did that thing where you blot the fluid on the sterile gauze and it did not produce a "halo". The guy was big and he had scoliosis, so i figured I had missed off the midline a little and got into vasculature. After two attempts, the pt did not want any more attempts even under ultrasound. By that time, the pt had a negative CT and his pain was totally gone after Compazine, so i felt safe discharging him. Now reflecting back, could it have been frank blood in the CSF from hemorrhage that was missed on CT. Is it possible to have a blled so big that you get blood in the CSF but miss it on CT? I always thought the ones that you miss on CT but catch on LP were microscopic blood or blood tinged or xanthrochromic, not frank blood. Is that right?

My impression is that this was likely a traumatic tap (twice), given his scoliosis. Still, I don't think I would have felt "safe" ruling out SAH just given pain resolution with compazine and a negative CT. Next time, you might consider sending the patient to IR for the procedure (or document heavily that the risks/benefits were provided and that the patient still refused the procedure).

In fact, this very question was addressed in one of the recent EMRA mags
(I think their question was, the RBC ct went from 4,000 to 400 in tubes 1 to 4; is this just a traumatic tap?). They advocate further neuroimaging (ie, CTA) and, if possible, having neurosurg weigh in with their thoughts.

Good questions!

 

[southerndoc]

If the RBC's remain the same in tube 4, then I would think more likely to be SAH (still could be the bloody tap though). If the RBC's decrease in tube 4, then it's less likely to be SAH (but still could be). Even with a bloody tap, the lab can still spin it down and check for xanthochromia. Xanthochromia shouldn't be present with a bloody tap.

It's a major problem in detecting SAH's.

 

[GeneralVeers]

I think in the future most physicians will consider the spinal tap for SAH to be a quant notion, like the pneumoencephalogram done on the Exorcist.

As CT technology improves, and MRIs become easier to obtain, they will hopefully supplant this barbaric (and inaccurate) procedure.

 

[GiJoe]

How do you tell between a bloody/traumatic tap and SAH? I had this guy with a new headache that had lasted four wks and tapped him twice yesterday and I got frank blood that would not clear twice. I did that thing where you blot the fluid on the sterile gauze and it did not produce a "halo". The guy was big and he had scoliosis, so i figured I had missed off the midline a little and got into vasculature. After two attempts, the pt did not want any more attempts even under ultrasound. By that time, the pt had a negative CT and his pain was totally gone after Compazine, so i felt safe discharging him. Now reflecting back, could it have been frank blood in the CSF from hemorrhage that was missed on CT. Is it possible to have a blled so big that you get blood in the CSF but miss it on CT? I always thought the ones that you miss on CT but catch on LP were microscopic blood or blood tinged or xanthrochromic, not frank blood. Is that right?

I would think, if you were getting frank blood on your tap, and it wasn't traumatic.... you should definitely see some blood on the ct

I make these folks sign out ama if they dont want further workup. reality is, when I tell them the speel of ct being 92-94% accurate and that an LP will make us close to a 100%, AND i show them the needle, they refuse the tap

 

[nevadan]

I would think, if you were getting frank blood on your tap, and it wasn't traumatic.... you should definitely see some blood on the ct

I make these folks sign out ama if they dont want further workup. reality is, when I tell them the speel of ct being 92-94% accurate and that an LP will make us close to a 100%, AND i show them the needle, they refuse the tap

I have seen some herpes meningitis in HIV patients have frankly bloody csf. Tapped the patients in two different levels and both frankly bloody.

 

[kungfufishing]

Anecdotally, I've seen two CT negative LP positive leaking intracranial aneurysms. Both had CSF that did not clear and had a lightly orange hue. The first lady I'll never forget because she seized during the LP. As soon as the CSF started flowing on the second guy, I thought "this looks like that lady...".
Having said that, the next test is usually a CTA. As much as I enjoy the LP, I do wonder how long it will be before we are using CT/CTA instead (yes, I've read the recent lit that says we aren't quite there).