<Tr> <Th> eMedicine </Th> <Td> 80773 </Td> </Tr> <Tr> <Td_colspan="2"> (edit on Wikidata) </Td> </Tr> <P> Lumbar puncture (LP), also known as a spinal tap, is a medical procedure in which a needle is inserted into the spinal canal, most commonly to collect cerebrospinal fluid (CSF) for diagnostic testing . The main reason for a lumbar puncture is to help diagnose diseases of the central nervous system, including the brain and spine . Examples of these conditions include meningitis and subarachnoid hemorrhage . It may also be used therapeutically in some conditions . Increased intracranial pressure (pressure in the skull) is a contraindication, due to risk of brain matter being compressed and pushed toward the spine . Sometimes, lumbar puncture cannot be performed safely (for example due to a severe bleeding tendency). It is regarded as a safe procedure, but post-dural - puncture headache is a common side effect . </P> <P> The procedure is typically performed under local anesthesia using a sterile technique . A needle is used to access the subarachnoid space and fluid collected . Fluid may be sent for biochemical, microbiological, and cytological analysis . </P>

Where does the needle go for a spinal tap