Bilic et al developed an equation for estimating the lumbar puncture depth for a child. The authors are from University Hospital Center Zagreb in Croatia.

Patient selection: infants and children (upper age not available)



(1) age of the patient

(2) body weight in kilograms


For an infant less than 3 months old the depth ranged from 1.0 to 1.5 cm (10-15 mm).


For a child >= 3 months old:


mean depth of insertion in cm =

= (0.07 * (body weight)) + 1.3

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