Needle-entry angle for lumbar puncture in children as determined by using ultrasonography

The purpose of this study was to evaluate the angle for performing lumbar punctures in children aged 0 to 12 years. We hypothesized that the angle changes for different stages of development.

Children aged 0 to 12 years who presented to the Yale-New Haven Children's Hospital at a low-acuity triage level, in need of a lumbar puncture, their accompanying siblings and authors' children were eligible for the study. Subjects in 3 age groups were recruited and grouped as follows: group 1, 0 to 12 months; group 2, 12 to 36 months; and group 3, 3 to 12 years. Ultrasound images of the L3-L4 and L4-L5 lumbar space were taken with subjects in the lateral recumbent and sitting positions. The angle from the interspinous space to the skin was measured.

Thirty-six subjects were included. The mean angles in the lateral recumbent and sitting positions were group 1, 47.8° (SD: 8.2) and 51.1° (SD: 8.5), respectively; group 2, 58.8° (SD: 6.8) and 59.6° (SD: 5.5); and group 3, 60.5° (SD: 6.6) and 61.9° (SD: 4.0). The results of group 1 were significantly different from those of groups 2 or 3 in both positions (lateral recumbent P = .00526 and 0.00160; sitting P = .0499 and .00282).

The angle for lumbar puncture was more acute for infants than for older children in this study. Future studies should assess the difference in success rates of lumbar punctures when clinicians have knowledge of these angles.