CPT code 33858: Aortic graft, ascending aorta, dissection2026 Medicare rate & RVUs in California

CMS doesn’t publish an office rate for 33858 in California.

Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.

What 33858 covers

Code 33858 describes open replacement of the ascending thoracic aorta with a graft to treat aortic dissection, commonly an acute dissection involving the ascending segment. Cardiothoracic surgeons perform this major operation in a hospital operating room. Cardiopulmonary bypass may be used, but its use does not change the code. The procedure addresses the dissected ascending aorta, rather than disease confined to another aortic segment.

Report the code when the operative report supports graft replacement of the ascending aorta specifically for dissection. Documentation should identify the dissection, the segment treated, and the graft replacement performed; distinguish this service from code 33859, for ascending-aortic graft replacement for other disease. The CMS 90-day global includes the day-before preoperative visit and related postoperative care during the following 90 days. For multiple procedures in the same session, the highest-valued procedure is paid in full and others are subject to the standard 50% reduction. An assistant at surgery may be paid; co-surgeon payment requires supporting documentation, and team surgery is not permitted.

This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.

Where 33858 pays more and less in California

The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.

29 of 29 payment localities

How the 33858 rate is calculated

Each of 33858’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.

Payment rules and modifiers for 33858

33858 has a 90-day global period: related visits in that window are included in the surgery payment.

What modifiers do to the payment

When to use modifier 51

33858 compared with similar codes

How to choose

33859Aortic graftNon-dissection disease

Both describe ascending-aortic graft replacement. Choose 33858 when the indication is aortic dissection; 33859 applies to other disease.

33863Aortic graftValve conduit, coronary reconstruction

Compare the operative work with the full descriptor for 33863, which identifies additional operative elements; 33858 is selected for graft replacement specifically for dissection.

33866Aortic graftHemiarch extension

Code 33866 describes aortic hemiarch graft work. Use 33858 for ascending-aortic graft replacement for dissection when the reported work is not the hemiarch service described by 33866.

Codes related to 33858

Related codes aren’t interchangeable: bill the code that matches the service performed.

Where these rates come from

FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.

CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027

Open CMS sourceHow we calculate rates