In my opinion, you can bill 22845 for L2-3, L3-4 and 22845-59 for L5-S1. According to your example, you have a gap between L4-L5. This also follows in line with CPT Assistant 11-1-2007...
Question: What is the appropriate code to report if anterior instrumentation is inserted at vertebral segments C3-4 and additional instrumentation is inserted at C6-7, but vertebral segments C4-5 and C5-6 are not fused? Are the anterior instrumentation codes assigned strictly by the TOTAL number of spinal segments with instrumentation applied (ie, 22846) or is the appropriate code chosen based on the vertebral segments involved in each separate construct (ie, 22845, 22845 59)?
Answer: Anterior instrumentation codes 22845-22847 may be reported separately with modifier 59, Distinct procedural service, appended when the procedure involves the work of putting two separate plates in the spine at different locations. Therefore, in this clinical scenario, it would be appropriate to report CPT code 22845, Anterior instrumentation; 2-3 vertebral segments, for C3-4 and CPT code 22845 with modifier 59 for C6-7.
As you can see by this article, when there is a "jump" in segments, as in your case L3-4 (no L4-L5) then L5-S1, you could bill for both.
Does this answer your question or only create more?