Arthrd cmbn 1ntrspc ea addl
CPT 22634 is an add-on code used when a surgeon performs spinal fusion (arthrodesis) on additional intervertebral spaces during the same surgery beyond the first level. This code cannot be billed alone and must accompany a primary fusion code.
This calculator gives a typical-case estimate using standard Medicare modifier rules. Actual payment depends on payer policies, documentation, code-specific CMS status indicators, and locality. Verify before billing.
RVU breakdown
Conversion factor: 32.3465 · Source: CMS MPFS RVU25A · Confidence: High
NCCI bundling edits
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Billing tips
Report 22634 for each additional interspace beyond the first level; if three levels are fused using combined approach, bill primary code once and 22634 twice
Impact: Each instance of 22634 generates $470.97 Medicare payment; missing one additional level loses this full amount per level
Verify the primary fusion code is appropriate for combined approach (e.g., 22633); 22634 cannot be billed with anterior-only or posterior-only primary codes
Impact: Billing with wrong primary code results in 100% denial of 22634; proper pairing is essential for any reimbursement
Document each interspace separately in operative report with specific vertebral levels (e.g., L3-L4, L4-L5) to support multiple units of 22634
Impact: Inadequate level-specific documentation triggers 30-40% of denials in post-payment audits; clear documentation prevents $470.97 recoupment per level
Do not append modifier 51 to 22634 as it is an add-on code; NCCI guidelines exempt add-on codes from multiple procedure payment reductions
Impact: Improper modifier 51 use may trigger payer system edits causing delayed payment or unnecessary manual review
When billing to Medicare, ensure 22634 appears on same claim as primary fusion code; split claims will deny the add-on code
Impact: Split billing causes automatic denial requiring resubmission, delaying payment by 30-60 days
For revision fusion cases, document why additional levels were medically necessary versus staged procedure planning; payers scrutinize multi-level revisions
Impact: Medical necessity denials in revision cases average 25% without proper documentation; successful appeals require 60-90 days
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