Clinical indications for blood and CSF collection included rule-out diagnoses (i.e., clinical assessment to eliminate from consideration the possible presence of a condition or disease including pseudo-tumor cerebri, meningitis, and subarachnoid hemorrhage), headaches, ventriculoperitoneal shunt taps, craniectomies, and blood/tissue diseases such as leukemia that required CSF access in diagnosis or treatment.
Source: wiktionary