Division of the scalenus anticus muscle with resection of a cervical rib, performed to decompress neurovascular structures at the thoracic outlet.

Verified May 8, 2026 · 7 sources ↓

Medicare: $494.33
Work RVU: 9.67
Global, days: 90
Region: Other

Drawn from CMSAAPCCapitalhealthJvascsurgEmedny

Documentation requirements

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

Source · Editorial brief grounded in 7 cited references ↓

Operative note must name the surgical approach (e.g., supraclavicular or transaxillary) — 'standard approach' flags audits.
Document confirmation of cervical rib presence, including preoperative imaging (X-ray, CT, or MRI) showing the anomalous rib.
Record the specific neurovascular structures compressed and intraoperative findings at the thoracic outlet.
Note failed conservative treatment (physical therapy, NSAIDs, postural training) and duration prior to surgical decision.
If additional procedures were performed (e.g., 64713 brachial plexus decompression or 21615 first rib resection), document each as a distinct surgical step with separate indication.
Include positive findings from provocative TOS testing (Adson's, ROOS, elevated arm stress test) in the preoperative workup note.

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 50 Bilateral procedure 51 Multiple procedures 52 Reduced services 59 Distinct service LT Left side RT Right side 80 Assistant surgeon 62 Co-surgeons

What this code covers

Source · Editorial summary grounded in 7 cited references ↓

CPT 21705 describes open division of the scalenus anticus muscle combined with excision of a cervical rib. This is the operative step up from 21700 — use 21700 when the cervical rib is not resected, and 21705 when it is. The procedure addresses thoracic outlet syndrome (TOS) in which an anomalous cervical rib, together with the scalenus anticus, compresses the brachial plexus or subclavian vessels.

The 90-day global period covers all routine postoperative management through day 90. Unrelated E/M visits in that window require modifier 24; a significant, separately identifiable E/M on the same day as surgery requires modifier 25. When neurogenic TOS is accompanied by brachial plexus decompression (64713) or first rib resection (21615/21616), those codes are separately reportable — document the distinct surgical steps clearly.

Payers treating 21705 as cosmetic or not medically necessary is the leading coverage risk. Capital Health Plan and similar managed care organizations publish explicit clinical criteria for TOS surgery, typically requiring failed conservative therapy, positive provocative testing, and imaging confirmation of a cervical rib. Pre-authorization is standard; bill 21705 with the matching ICD-10 (Q76.5 for cervical rib, G54.2 for thoracic outlet syndrome) to avoid medical necessity denials.

RVU & reimbursement

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

Source · CMS Physician Fee Schedule, RVU26A · January 2026

Work RVU vs. total RVU

The work RVU (9.67) is the surgeon's own effort — the figure physician pay and productivity targets are built on. The total RVU (14.8) adds practice overhead and malpractice, and is what drives the Medicare payment below.

Work RVU	9.67
Practice expense RVU	2.65
Malpractice RVU	2.48
Total RVU	14.8
Medicare national rate	$494.33
Global period	90 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	$494.33
HOPD (APC 5114) Hospital outpatient department	$7,413.38
ASC (PI G2) Ambulatory surgical center (freestanding)	$3,695.53

Common denial reasons

The recurring reasons claims for CPT 21705 get rejected.

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

Medical necessity denial: payer requires documented failed conservative therapy before approving surgical TOS intervention.
ICD-10 mismatch: billing G54.2 or Q76.5 without supporting imaging or physical exam findings in the chart.
Bundling denial when 21705 and 21700 are billed together — 21705 already includes the scalene division; 21700 is not separately reportable.
Missing prior authorization: most commercial payers require pre-auth for TOS decompression surgery.
Wrong code selection: using 21705 when no cervical rib was resected — that scenario is 21700.

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 7 cited references ↓

01What is the difference between CPT 21700 and 21705?

21700 covers division of the scalenus anticus alone, without removing a cervical rib. 21705 is used when the cervical rib is also resected. The operative note must confirm rib excision to support 21705 — if the rib was identified but not removed, bill 21700.

02Can 21705 and 21615 be billed together?

Yes, when both a cervical rib (21705) and a first rib (21615) are resected in the same session, both codes are separately reportable. Document each resection as a distinct surgical step. Modifier 51 may apply for the secondary procedure depending on payer rules.

03Is prior authorization required for 21705?

Nearly universally yes for commercial payers. Most follow clinical criteria requiring imaging confirmation of a cervical rib, positive provocative TOS testing, and failed conservative management of specified duration. Obtain auth before scheduling.

04What ICD-10 codes are typically paired with 21705?

Q76.5 (cervical rib) and G54.2 (cervical root disorders / thoracic outlet syndrome) are the primary pairings. Some payers also accept M54.2 for cervicalgia when documented in the context of TOS. Confirm the diagnosis is supported by imaging in the record.

05How does the 90-day global period affect post-op billing for 21705?

All routine post-op visits, wound checks, and stitch removals through day 90 are included in the global. Append modifier 24 to an E/M for an unrelated problem during that window. If a complication requires a return to the OR for a related procedure, use modifier 78.

06Is 21705 ever performed bilaterally, and how is that billed?

Bilateral cervical ribs can occur, though bilateral same-session surgery is uncommon. If performed bilaterally in one session, append modifier 50 and follow your payer's bilateral payment policy — Medicare typically pays 150% of the single-procedure allowable.

Sources & references

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

Mira Scribe

Mira's AI scribe captures the approach (supraclavicular vs. transaxillary), confirmation of cervical rib resection, specific neurovascular structures decompressed, and intraoperative findings from dictation. It flags automatically if the note lacks a named approach or omits confirmation that the cervical rib was actually excised — the two most common reasons auditors downcode 21705 to 21700 or deny the claim outright.

See how Mira captures CPT 21705 documentation