Anesthesia Coding Alert

Question: How should I determine the number of segments affected by spinal instrumentation procedures? For example, should I count L3-L4 and L4-L5 as two segments, or three?

Wisconsin Subscriber

Answer: A vertebral "segment" represents a single complete vertebral bone with its associated articular processes and laminae. A vertebral "interspace" is the non-bony area between two adjacent vertebral bodies, according to CPT.

Because a segment represents a complete vertebra, a spinal fixation running from L2 through L5 (for example) comprises four segments. In your situation, L3-L4 and L4-L5 counts as three segments.

Be sure to check other terminology in addition to counting your segments. A fixation that is "non-segmental" may run through many egments with only two fixation points at either end (such as Harrington rods). Segmented fixations, on the other hand, have multiple fixation points over the course of the fixation (unless it's only one segment, which only has two fixation points).

To code correctly, you should first determine whether the instrumentation is segmental or non-segmental. Next, determine whether the instrumentation is anterior or posterior.

Finally, you should count how many segments (i.e., vertebral bones) are involved. Suppose a physician places anterior spinal segmental spinal instrumentation starting at T8 and running through L2. This involves seven segments, or vertebral bones. You should report 22846 (Anterior instrumentation; 4 to 7 vertebral segments) or anesthesia code 00670 (Anesthesia for extensive spine and spinal cord procedures [e.g., spinal instrumentation or vascular procedures]).