An evaluation of ultrasound imaging for identification of lumbar intervertebral level.

The accuracy of ultrasound imaging to identify lumbar intervertebral level was assessed in 50 patients undergoing X-ray of the lumbar spine. Using an ultraviolet marker, an anaesthetist attempted to mark the L2/3, L3/4 and L4/5 intervertebral spaces. A radiologist unaware of these marks attempted to mark the same spaces with the aid of ultrasound imaging. X-ray-visible pellets were taped to the back at the various marks prior to lateral lumbar X-ray. Ultrasound imaging identified the correct level in up to 71% of cases, but palpation was successful in only 30% (p < 0.001). Up to 27% of marks using the palpation method were more than one spinal level above or below the assumed level using palpation, but none were more than one level high or low using ultrasound guidance.