Add-on code for harvesting and using morselized autograft bone in spine surgery via a separate skin or fascial incision.

Verified May 8, 2026 · 6 sources ↓

Medicare: $147.30
Total RVUs: 4.41
Global, days
Region: Spine

Drawn from CMSSrsCodingforcliniciansGuidelinesAAPC

Documentation requirements

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

Source · Editorial brief grounded in 6 cited references ↓

Explicit statement that a separate skin or fascial incision was made for graft harvest — 'same incision' language triggers 20936, not 20937
Donor site identified by name (e.g., iliac crest, rib) in the operative note
Description of graft preparation confirming morselized (particulate) form, not structural block
Primary spine procedure CPT code documented — 20937 is an add-on and cannot be billed without a qualifying primary code
Laterality of donor site documented (left or right iliac crest) for audit trail

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 ↓

20937 covers the harvest and use of the patient's own morselized bone graft in spinal surgery when the graft is obtained through a separate skin or fascial incision — most commonly from the iliac crest. The separate incision is what distinguishes this code from 20936, which covers local graft taken from within the same operative field. Because 20937 is a ZZZ global add-on, it always pairs with a primary spine procedure; it cannot stand alone.

The code assigns value to the harvest work, not the implantation. If local bone fragments (laminar fragments, spinous processes, facets) are gathered from within the primary incision, 20936 applies instead — and that code carries no work RVU. Use 20937 only when the operative note explicitly documents a separate incision for graft harvest.

Top billing contexts are posterior and transforaminal lumbar interbody fusions (e.g., 22612, 22633) and spinal deformity corrections. As an add-on code, 20937 is modifier 51 exempt. No modifier is needed for routine reporting alongside the primary procedure.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU	2.72
Practice expense RVU	0.9
Malpractice RVU	0.79
Total RVU	4.41
Medicare national rate	$147.30
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	$147.30

Common denial reasons

The recurring reasons claims for CPT 20937 get rejected.

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

Operative note says 'local bone graft' or describes harvest from within the primary incision — payer downcodes to 20936 or denies 20937
Billed without a valid primary spine procedure code — 20937 is an add-on and is not payable as a standalone
Missing documentation of a separate incision; audit teams flag notes that state only 'standard approach' or omit donor site details
Modifier 51 incorrectly appended — 20937 is modifier 51 exempt and the modifier can trigger unnecessary review or reduction

Frequently asked questions

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

01What is the difference between 20936 and 20937?

20936 covers local bone harvested from within the same incision as the primary procedure (e.g., laminar fragments, spinous processes). 20937 requires a separate skin or fascial incision — typically iliac crest harvest. Only 20937 carries a meaningful work RVU; 20936 has no assigned work value under CMS.

02Does 20937 need modifier 51?

No. 20937 is an add-on code and is modifier 51 exempt. Appending modifier 51 is incorrect and can trigger unnecessary payment review.

03Can 20937 be billed with a TLIF (22633)?

Yes, if the surgeon harvested morselized autograft through a separate incision. The decompression component is bundled into 22633, but a separately incised iliac crest harvest supports 20937. The operative note must explicitly document the separate incision.

04Is 20937 billable for rib graft obtained during a spinal deformity case?

Yes. Rib harvest performed through a separate incision qualifies for 20937. The Scoliosis Research Society notes that rib harvesting is an independent procedure distinct from local bone collection and appropriately coded as 20937, not 20936.

05Can both 20930 and 20937 be billed on the same case?

Yes, when both allograft (20930) and autograft harvested through a separate incision (20937) are used in the same spinal procedure, both codes are reportable. Document each graft type and source distinctly in the operative note.

06What primary codes typically pair with 20937?

Most commonly posterior lumbar fusion codes (22612, 22630, 22633), anterior lumbar fusion codes, and spinal deformity arthrodesis codes (22800–22804). 20937 must always be listed in addition to an eligible primary procedure.

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 donor site by name, confirms a separate skin or fascial incision was made, and records the graft form as morselized — the three elements auditors check first on 20937 claims. That documentation prevents the most common denial: the payer downgrading to 20936 because the note didn't distinguish the harvest site from the primary operative field.

See how Mira captures CPT 20937 documentation