A Comparison of Visualization Between Shamrock Technique and Paramedian Transverse Scan in Lumbar Plexus Blockade

This scanning technique is performed in the lateral decubitus position with the side of interest facing upwards. The transducer is placed in the transverse plane on the flank of the patient cranially to the iliac crest. The quadratus lumborum muscle is identified medial to the aponeurosis of the transversus abdominis muscle. With the psoas muscle anterior to the transverse process, the erector spinae muscle posterior to the transverse process, and the quadratus lumborum muscle attached to the apex of the transverse process of L4.

The ultrasound transducer is positioned 4 cm lateral to the midline along the intercristal line and just above the iliac crest. The transducer is also directed slightly medially.