The use of ultrasound in performing a neuraxial block is a relatively new addition to the procedure. It is particularly useful in patients where landmarks used to locate appropriate intervertebral spaces for needle insertion are difficult to palpate, or the patient has a spinal abnormality. Needle insertion is easiest if maximum flexion of the lumbar spine is attained, fully opening the intervetebral spaces (see right). This can be done in the following ways:

The sitting position is best for performing the ultrasound scan and administering the neuraxial block. The patient is positioned seated on a flat operating table close to the edge where the anaesthesiologist is standing. Their feet are raised on a stool, and the patient flexes forward, pushing their back out, resting their forearms on their thighs. Their neck is also flexed with their chin towards their chest. An assistant may help to maintain the patient in a flexed position during the ultrasound and block.

This position is used if the patient is sedated or uncooperative during the block procedure. The patient is positioned lying on their side on a flat table, with their back close to the edge of the table. Their hips and knees are fully flexed and their neck is also flexed forward with their chin towards their chest. Their shoulders and hips should be at a right angle to the surface of the table.