A CSF sample shows blood in all tubes after lumbar puncture. This pattern most strongly indicates which condition?

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Multiple Choice

A CSF sample shows blood in all tubes after lumbar puncture. This pattern most strongly indicates which condition?

Blood in all CSF tubes after a lumbar puncture points to bleeding within the subarachnoid space. When the bleed is truly intrathecal, the blood distributes throughout the CSF as it is sampled, so every tube shows red cells. In a traumatic tap, the needle causes bleeding at the puncture site, so the first tube tends to be bloodier and the amount of blood decreases in subsequent tubes as CSF is collected and the sample becomes less contaminated. Thus this uniform appearance across tubes is the strongest clue for a subarachnoid hemorrhage. Xanthochromia can appear later in SAH, but the key early cue is the pattern of blood across all tubes.

Blood in all CSF tubes after a lumbar puncture points to bleeding within the subarachnoid space. When the bleed is truly intrathecal, the blood distributes throughout the CSF as it is sampled, so every tube shows red cells. In a traumatic tap, the needle causes bleeding at the puncture site, so the first tube tends to be bloodier and the amount of blood decreases in subsequent tubes as CSF is collected and the sample becomes less contaminated. Thus this uniform appearance across tubes is the strongest clue for a subarachnoid hemorrhage. Xanthochromia can appear later in SAH, but the key early cue is the pattern of blood across all tubes.

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