Determining the Spinal Canal Depth in Neonates Using Bedside Ultrasonography

Objective To provide a gestation age- and weight-specific mathematical formula for predicting the optimal depth of spinal needle insertion. Methods The study included 127 neonates between 28 and 40 weeks of gestation and weighing 700 to 4000 grams, and a total of 202 ultrasound examinations were performed. Anterior and posterior borders were delineated using ultrasound and measured as spinal canal depth in lateral decubitus position at L3–L4 vertebral interspace. The mid-spinal canal depth (MSCD) was calculated. Results Spinal canal dimensions showed an increasing trend with an increase in weight and post-menstrual age of the babies. The best correlation was found between weight and MSCD with an r 2 of 0.85, which is given by the formula MSCD (cm) = 0.2 × weight in kg + 0.45. Conclusion Knowledge of the spinal canal depth using the formula may facilitate accurate needle placement, thereby decreasing traumatic lumbar puncture.