Surgical · Other

Open surgical removal of a thrombus from an arteriovenous fistula used for hemodialysis access, without fistula revision.

Verified May 8, 2026 · 5 sources ↓

Medicare: $565.81
Work RVU: 10.73
Global, days: 90
Region: Other

Drawn from CMSAAPC

Documentation requirements

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

Source · Editorial brief grounded in 5 cited references ↓

Specify that this was an open (not percutaneous/endovascular) approach to the AV fistula.
Confirm no anastomotic or fistula revision was performed — distinguishes 36831 from 36833.
Document fistula location (e.g., radiocephalic forearm, brachiocephalic upper arm).
Record pre-op and post-op fistula patency assessment (thrill, Doppler, or intraoperative flow check).
Note whether the AV fistula is autogenous or nonautogenous (prosthetic graft) — relevant for payer review.
Include the clinical indication establishing dialysis dependence or imminent loss of access.

Applicable modifiers

Modifiers commonly billed with this code.

Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual

22 Increased complexity 24 Unrelated E/M during global 25 Significant separate E/M 51 Multiple procedures 58 Staged or related 76 Repeat, same physician 77 Repeat, another physician 78 Unplanned return — related 79 Unrelated during global 80 Assistant surgeon LT Left side RT Right side

What this code covers

Source · Editorial summary grounded in 5 cited references ↓

CPT 36831 describes an open thrombectomy of an arteriovenous (AV) fistula — the surgeon makes a direct incision, evacuates the clot obstructing the fistula, and closes without revising the anastomosis or fistula anatomy. This distinguishes it from 36832 (open revision without thrombectomy) and 36833 (revision with thrombectomy). All three are open procedures; percutaneous or endovascular approaches are coded separately.

The procedure is performed almost exclusively in dialysis-dependent patients whose AV fistula has thrombosed, threatening immediate loss of hemodialysis access. Typical locations are forearm or upper arm. The 90-day global period means routine follow-up, wound checks, and access monitoring visits through day 90 are bundled — bill unrelated E/M services with modifier 24 and related staged or return procedures with the appropriate return-to-OR modifier.

CMS billing guidelines (LCD attachment CV-027) explicitly group 36831 with 36832 and 36833 as open procedures, distinguishing them from percutaneous transluminal codes. Payers audit this code closely when interventional alternatives were available or when revision work is documented but 36833 was not billed. Document clearly that thrombectomy was performed and that no revision of the fistula was performed to justify 36831 over 36833.

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 (10.73) is the surgeon's own effort — the figure physician pay and productivity targets are built on. The total RVU (16.94) adds practice overhead and malpractice, and is what drives the Medicare payment below.

Work RVU	10.73
Practice expense RVU	3.46
Malpractice RVU	2.75
Total RVU	16.94
Medicare national rate	$565.81
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	$565.81
HOPD (APC 5184) Hospital outpatient department	$5,685.01
ASC (PI A2) Ambulatory surgical center (freestanding)	$3,187.37

Common denial reasons

The recurring reasons claims for CPT 36831 get rejected.

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

Revision work documented in the operative note triggers payer downcoding or denial in favor of 36833 (thrombectomy with revision).
Billed with a percutaneous or interventional thrombectomy code on the same date without a modifier establishing a distinct service.
Missing documentation of open surgical approach — payers deny when the operative note is ambiguous about percutaneous versus open access.
Global period conflict: post-op E/M visits billed without modifier 24 are automatically bundled into the 90-day global and denied.
Lack of documented dialysis dependence or clinical necessity for urgent restoration of access.

Frequently asked questions

Source · Generated from the editorial pipeline, verified against 5 cited references ↓

01What is the difference between 36831, 36832, and 36833?

36831 is open thrombectomy only — no revision. 36832 is open revision without thrombectomy. 36833 is open revision with thrombectomy. If your operative note documents both clot removal and any revision of the fistula or anastomosis, bill 36833, not 36831.

02Can 36831 be billed with a percutaneous thrombectomy code on the same date?

Only if a genuinely distinct service was performed on a separate access site or vessel, supported by separate documentation and an appropriate modifier (59 or XS). Billing both for the same fistula on the same day without that documentation will trigger an NCCI bundling denial.

03What does the 90-day global period cover for 36831?

All routine post-op care, wound checks, and access-related follow-up through day 90 are bundled. Unrelated E/M services in that window need modifier 24. A return to the OR for a related complication (e.g., re-thrombosis requiring repeat open thrombectomy) bills with modifier 78.

04Is 36831 appropriate for thrombosed AV grafts as well as native fistulas?

Yes — the code applies to both autogenous (native vein) and nonautogenous (prosthetic graft) AV fistulas. Document which type is present, as payers may request this for coverage review.

05How does site of service affect payment for 36831?

HOPD and ASC payments differ materially — see the site of service comparison table on this page. The procedure is not performed in an office setting. Confirm the facility type before submitting to ensure the correct fee schedule applies.

06Can modifier 50 be used if both arms have thrombosed AV fistulas addressed in the same session?

Bilateral AV fistulas are uncommon, but if two separate fistulas on contralateral limbs are each thrombectomized in the same operative session, modifier 50 (or LT/RT pair) with supporting documentation is appropriate. The operative note must clearly describe two distinct open procedures on two distinct access sites.

Sources & references

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

Mira Scribe

Mira's AI scribe captures the surgical approach (open incision vs. percutaneous), confirmation that thrombectomy was performed without fistula revision, fistula location and type (autogenous vs. nonautogenous), and intraoperative patency confirmation. This prevents the most common audit flag for 36831: operative notes that describe revision work inconsistent with the billed code, triggering payer downcoding to 36833.

See how Mira captures CPT 36831 documentation