CSF RBC count in successful first-attempt lumbar puncture: the interest of atraumatic needle use

The objective of this study is to analyze CSF red blood cell (RBC) count from first-attempt lumbar punctures and to analyze parameters associated with first-attempt lumbar punctures and hemorrhagic lumbar puncture. This is a prospective analysis of consecutive patients who underwent lumbar puncture for any reason other than suspected acute subarachnoid hemorrhage. Analyzed parameters were the following: age, indication for lumbar puncture, aPTT ratio, PTT, platelet count, patient's position, needle type (atraumatic/standard), needle diameter, person performing lumbar puncture (medical student/resident/attending physician), number of lumbar levels punctured, necessity of needle repositioning, CSF RBC and white blood cell count, and protein level. Lumbar puncture resulting in RBC count > 5 RBC/mm² was classified as hemorrhagic lumbar puncture (different cut-offs were studied: > 5/> 10/> 100/> 500/> 1000 RBC). In total, 169 elective lumbar punctures in 165 different patients were included. First-attempt lumbar puncture occurred in 22% > 5 RBC, in 19.5% > 10 RBC, in 4.5% > 100 RBC, in 3% > 500 RBC, and 1.5% > 1000 RBC count. First-attempt lumbar puncture was associated with non-hemorrhagic lumbar puncture for each of the RBC count cut-offs (OR for non-hemorrhagic lumbar puncture in first-attempt lumbar puncture 2.8, 95% CI 1.4-5.7). The presence of a hemorrhagic disorder (concerning cerebral amyloid angiopathy in all patients) and higher aPTT ratio were associated with hemorrhagic lumbar puncture. Atraumatic needle use was associated with non-hemorrhagic lumbar puncture for RBC count cut-offs ≤ 5 and ≤ 10 RBC (OR for non-hemorrhagic lumbar puncture in atraumatic needle use 2.5 [95% CI 1.3-4.8] and 2.2 [95% CI 1.1-4.4], respectively). First-attempt lumbar puncture and hemorrhagic lumbar puncture were not associated with other parameters. Slightly elevated CSF RBC count after first-attempt lumbar puncture occurs relatively frequently, but is even more frequent in non-first-attempt lumbar puncture. Atraumatic needle use is associated with non-hemorrhagic lumbar puncture.