Ultrasound evaluation of lumbar spine anatomy in newborn infants: implications for optimal performance of lumbar puncture.

An ultrasound evaluation of lumbar spine anatomic landmarks relevant for lumbar puncture was performed in 199 newborn infants. Effects of 6 patient positions and gestational age on interspinous process distance, subarachnoid space width, predicted needle entry angle, and needle insertion depth were assessed. Our results identify optimized conditions for lumbar puncture: sitting the infant with hips flexed, a needle entry angle of 65-70 degrees, and proper needle insertion depth (calculated as 2.5 × weight in kilograms + 6 in millimeters).