Structural autograft harvested from the patient during a spinal procedure, reported as an add-on to the primary spine surgery code.

Verified May 8, 2026 · 6 sources ↓

Medicare: $163.33
Total RVUs: 4.89
Global, days
Region: Spine

Drawn from CMSGuidelinesAAPCAAOS

Documentation requirements

What must appear in the operative or office note to support the claim.

Source · Editorial brief grounded in 6 cited references ↓

Identify the specific harvest site (e.g., iliac crest, fibula) separate from the primary surgical field
Document a distinct incision made for graft harvest — not local bone from the decompression site
Describe the structural role of the graft at the spinal fusion level (load-bearing, not purely morselized fill)
Reference the primary spine procedure code in the operative note to support add-on code linkage
Note graft dimensions and placement location to support medical necessity and audit review

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 59 Distinct service 62 Co-surgeons 76 Repeat, same physician 77 Repeat, another physician 78 Unplanned return — related

What this code covers

Source · Editorial summary grounded in 6 cited references ↓

20938 is an add-on code for a structural bone autograft performed during spine surgery. The graft is harvested from the patient's own body through a separate incision made during the same operative session — distinguishing it from allograft (donor) options. Because it's an add-on, it never stands alone: it must be reported alongside the primary spinal procedure code, and it inherits a ZZZ global period, meaning it folds into whatever global period the primary code carries.

This code is used by orthopedic surgeons and neurosurgeons when structural support — not just gap-filling — is needed at the fusion site. The separate harvest incision is the key clinical differentiator. If graft material is taken from local bone already exposed in the surgical field (e.g., laminectomy bone), that's not separately billable under 20938. The graft must come from a distinct harvest site with its own incision.

Payer scrutiny on this code centers on two things: whether the operative note explicitly documents a separate incision for harvest, and whether the structural (load-bearing) nature of the graft is described. Notes that just say 'autograft was used' without specifying site, incision, and structural role are routinely flagged. Carelon and similar managed care organizations require documentation that the procedure meets clinical appropriateness criteria under their spine surgery guidelines before authorizing payment.

RVU & reimbursement

Component RVUs and Medicare national rate. Actual payment varies by GPCI locality.

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	2.94
Practice expense RVU	0.99
Malpractice RVU	0.96
Total RVU	4.89
Medicare national rate	$163.33
Global period	days

Payment by site of service

Medicare pays different rates by setting. HOPD typically pays substantially more than ASC for the same procedure.

Source · CMS OPPS Addendum B·ASC HCPCS payment rates·2026

Setting	Medicare rate (national)
Office (PFS non-facility) Procedure performed in physician's office	$163.33

Common denial reasons

The recurring reasons claims for CPT 20938 get rejected.

Source · Editorial brief grounded in CMS NCCI edits, AAOS coding appeals, and cited references ↓

Operative note fails to document a separate harvest incision, suggesting local bone use instead
Code billed without a primary spine procedure code — add-on codes cannot stand alone
Insufficient documentation of structural (load-bearing) graft function versus morselized autograft
Prior authorization not obtained under payer spine surgery clinical appropriateness guidelines
Graft harvest site not specified, leaving reviewers unable to confirm a distinct anatomical source

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 6 cited references ↓

01Can 20938 be billed without a primary spine surgery code?

No. 20938 is an add-on code with a ZZZ global period. It must accompany a primary spinal procedure code on the same claim. Submit it alone and it will deny.

02What's the difference between 20938 and 20937?

20937 covers morselized autograft — cancellous bone chips used to fill gaps. 20938 is for structural autograft, meaning the harvested bone provides mechanical, load-bearing support at the fusion site. The operative note must reflect which type was actually used.

03Does harvesting local bone from the laminectomy site qualify for 20938?

No. Local bone already exposed within the primary surgical field doesn't meet the threshold. A separate incision at a distinct harvest site — typically the iliac crest — is required to bill 20938.

04Which modifier applies if two co-surgeons each perform distinct parts of the spine procedure including the graft harvest?

Use modifier 62 when two surgeons operate as co-primaries on the same reportable procedure. Each surgeon reports their distinct operative work, and both append modifier 62 to the applicable codes.

05Does 20938 require prior authorization?

It depends on the payer. Carelon's spine surgery clinical appropriateness guidelines explicitly list bone graft procedures and require that authorization criteria are met. Check payer-specific PA requirements before the case — not after the denial.

06Is 20938 subject to modifier 51 reduction?

Add-on codes are exempt from modifier 51 reduction. Do not append modifier 51 to 20938; CMS and most payers exclude add-on codes from multiple procedure payment reduction rules.

Sources & references

Editorial content was developed using the following public sources. Last verified May 8, 2026.

Mira AI Scribe

Mira's AI scribe captures the harvest site by name, confirms a separate incision was made, and records the structural role of the graft at the fusion level — all from surgeon dictation. That documentation directly prevents the two most common denials: claims that only local bone was used, and notes too vague to establish structural versus morselized graft function.

See how Mira captures CPT 20938 documentation