Which interspace should a lumbar puncture be performed at and how can this be identified?

  • Lumbar puncture should not be performed at or above the L2/3 interspace:
    • In adults, the solid spinal cord ends at L1 (ranges from T11 to upper L3)
    • At this level the conus medullaris continues distally as the cauda equina
    • Puncture above this level risks damaging the cord
  • The L4/5 or L3/4 interspace is usually used
  • The L4 spinous process can be estimated using Tuffier’s line:
    • An imaginary line drawn between the iliac crests
    • Significant anatomical variation exists between patients
  • Alternative anatomic landmarks include:
    • The tip of the scapula in line with T7 spinous process
    • The tip of the 10th rib in line with L1 spinous process
Surface landmarks for vertebrae
(Jung et al.)