What should be done if a lumbar puncture (LP) results in a dry tap?

Updated: Aug 02, 2018
  • Author: Gil Z Shlamovitz, MD, FACEP; Chief Editor: Helmi L Lutsep, MD  more...
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Answer

Dry taps usually result from misplacement of the spinal needle. The most common mistake is a lateral displacement, which can easily be corrected by withdrawing the needle completely, reevaluating the patient’s anatomy, and reinserting the needle in the correct place and at the proper angle. In obese patients, the regular spinal needle might be too short, in which case a longer one should be used.

If the patient is dehydrated, a falsely negative dry tap may be obtained as a result of very low CSF volume and pressure. If this is suspected, attempt to rehydrate the patient before the procedure.


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