Improving Accuracy of Landmarks for Neuraxial Blocks in Pregnancy: The Sacral Anatomical Interspace Landmark (SAIL) Technique

The current standard technique aiming at identifying the L4-L5 intervertebral space as a reference point before performing a neuraxial block relies on the correct clinical estimation of the intercristal line. The classic intercristal line technique uses an imaginary line that intersects the iliac crests to determine a safe puncture level to access. In pregnant women, the classic technique fails to identify the safe puncture level 40 % of the time. The newly proposed Sacral Anatomical Interspace Landmark (SAIL) technique consists of using the sacral bone to determine a safe puncture level to access. Lumbar ultrasound will determine the accuracy of each clinical technique in identifying the L4-L5 interspace (target).