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Billing code 61598: Skull base approachMedicare rate & RVUs

Reports transpetrosal surgical exposure of the skull base to reach lesions near the petrous temporal bone, petroclival region, or brainstem.

CMS RVU26DEffective Oct 1, 2026109 payment localities48 Medicare services in 2024

Medicare pays $2,847.76 for 61598 nationally in a facility.

Medicare rate · 61598

Skull base approach

Swap in your local Medicare rate.

Work RVUs
35.62
Total RVUs
85.26
Global days
090

National rate · 2026

$2,847.76

Facility setting, before claim adjustments.

See every locality for 61598 → · Billed by an NP, PA or therapist? →

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

On this page 10 sections
  1. Medicare rate
  2. What 61598 covers
  3. By payment locality
  4. Rate map
  5. How it’s calculated
  6. Payment rules
  7. Similar codes
  8. Related codes
  9. Billing questions
  10. Sources

What 61598 covers

A transpetrosal approach creates access to the skull base through the petrous portion of the temporal bone. Neurosurgeons and otologic or neurotologic surgeons may use this corridor for selected lesions near the petrous bone, petroclival region, or brainstem. The operation is typically performed in a hospital operating room as part of complex skull base surgery; the operative report should identify the route and the exposure performed.

Report this code when the documented skull base exposure uses a transpetrosal corridor, rather than selecting it solely because a lesion is nearby. The record should distinguish the approach from the definitive treatment and describe relevant bone work and the operative target. This major surgery has a 90-day global period, including the day-before preoperative visit and related postoperative care during that period. When multiple procedures are performed in the same session, the highest-valued procedure is paid in full and other procedures are subject to the standard 50% reduction. Modifier 50 is inappropriate for this code. Assistant-at-surgery payment may be available; co-surgeon payment requires supporting documentation, and team surgery is 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 61598 pays more and less

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

109 of 109 payment localities

61598 office and facility rates by payment locality
Payment localityOfficeFacility
AlabamaUnavailable$2,485.28
Alaska*Unavailable$3,292.19
ArizonaUnavailable$2,739.60
ArkansasUnavailable$2,441.17
AtlantaUnavailable$2,970.79
AustinUnavailable$2,859.90
BakersfieldUnavailable$2,784.89
Baltimore/Surr. CntysUnavailable$3,070.22
BeaumontUnavailable$2,708.08
BrazoriaUnavailable$2,736.36

61598 rates by state

Office rate range in each state. Select a state to see its payment localities.

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Local rates. Clear comparisons.

Hover or focus a tile to see its rate range. Select it to open the state’s fee schedule.

View every state and territory as a table
61598 office rate range by state
State / territoryOffice rate rangeLocalities
AKNo published base rate1
ALNo published base rate1
ARNo published base rate1
AZNo published base rate1
CANo published base rate29
CONo published base rate1
CTNo published base rate1
DCNo published base rate1
DENo published base rate1
FLNo published base rate3
GANo published base rate2
GUNo published base rate1
HINo published base rate1
IANo published base rate1
IDNo published base rate1
ILNo published base rate4
INNo published base rate1
KSNo published base rate1
KYNo published base rate1
LANo published base rate2
MANo published base rate2
MDNo published base rate3
MENo published base rate2
MINo published base rate2
MNNo published base rate1
MONo published base rate3
MSNo published base rate1
MTNo published base rate1
NCNo published base rate1
NDNo published base rate1
NENo published base rate1
NHNo published base rate1
NJNo published base rate2
NMNo published base rate1
NVNo published base rate1
NYNo published base rate5
OHNo published base rate1
OKNo published base rate1
ORNo published base rate2
PANo published base rate2
PRNo published base rate1
RINo published base rate1
SCNo published base rate1
SDNo published base rate1
TNNo published base rate1
TXNo published base rate8
UTNo published base rate1
VANo published base rate2
VINo published base rate1
VTNo published base rate1
WANo published base rate2
WINo published base rate1
WVNo published base rate1
WYNo published base rate1

How the 61598 rate is calculated

Each of 61598’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.

How the rate is built · 61598

RVUs × geographic indexes × conversion factor

Swap in your local Medicare rate.

Work 35.62Practice expense 34.60Malpractice 15.04

85.2600 adjusted RVUs×$33.4009 conversion factor=$2,847.76

All indexes start at 1.000 (the national rate). Enter a ZIP or drag a slider.

Payment rules and modifiers for 61598

61598 has a 90-day global period: related visits in that window are included in the surgery payment.

CMS payment indicators · 61598

Skull base approach

RuleCMS valueWhat it means
Global period090Major surgery: the day before, the day of, and 90 days after are included.
Multiple procedures2Standard reduction: highest-valued procedure at 100%, others at 50%.
Bilateral (modifier 50)0The 150% bilateral adjustment doesn’t apply.
Assistant at surgery (80/81/82/AS)2Paid.
Co-surgeons (62)1Permitted with supporting documentation.
Team surgery (66)2Permitted.
Professional/technical0Physician service: no professional/technical split.
Split (54/55/56)0.11/0.76/0.13Share of the payment for pre-op, the procedure itself, and post-op care.

Global surgery period · 61598

Skull base approach

90-day global period ends

Dec 30, 2026

Covers Sep 30, 2026 through Dec 30, 2026 (92 days, including the day before surgery).

Visit on Oct 31, 2026

Day 30 of the 90-day post-op period: related follow-up care is included in the surgical payment.

  • 24 Unrelated E/M visit by the same physician
  • 79 Unrelated procedure (starts its own global period)
  • 58 Staged, more extensive, or therapy procedure that was planned
  • 78 Unplanned return to the operating room for a related complication
SurgeryVisit
Sep 23, 2026Jan 10, 2027

Pre-op dayGlobal period

What modifiers do to the payment

Modifier 51 · payment effect

With and without the modifier

61598 without 51 · national facility

$2,847.76

Skull base approach

61598-51 · Second procedure: 50%

$1,423.88

When this isn’t the highest-valued procedure in the session, Medicare pays 50% of its fee schedule amount (the highest is paid at 100%).

When to use modifier 51

61598 compared with similar codes

Compare codes

61598 vs 61595 vs 61596 vs 61597: national Medicare rates

Swap in your local Medicare rate.

  • 61598
    Skull base approach · 35.62 wRVU
    —
  • 61595
    Skull base approach · 32.9 wRVU
    —
  • 61596
    Skull base approach · 38.44 wRVU
    —
  • 61597
    Skull-base approach · 39.8 wRVU
    —

How to choose

61595Skull base approach
61598 identifies a transpetrosal route through the petrous temporal bone; 61595 is used for a transtemporal approach.
61596Skull base approach
Use 61596 when the documented exposure is transcochlear, rather than transpetrosal.
61597Skull-base approach
61597 represents a transcondylar skull base corridor. The operative route, not simply the lesion's location, separates it from 61598.

Codes related to 61598

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

Codes related to 61598
CodeHow it relatesNational office range
Used instead
61595Skull base approachUses a transtemporal rather than transpetrosal route to expose the skull base.No office rate
61596Skull base approachUses a transcochlear corridor for skull base exposure.No office rate
61597Skull-base approachUses a transcondylar corridor rather than a transpetrosal one.No office rate
61590Skull base approachAn infratemporal approach code for a different skull base corridor.No office rate

61598 billing questions

How is this approach distinguished from a transtemporal approach?

Choose this code when the operative report identifies a transpetrosal route through the petrous temporal bone. A transtemporal approach is a different skull base corridor.

Should the approach and the definitive operation be reported separately?

The approach code represents the surgical exposure, not the pathology being treated. Review the operative report and applicable coding instructions to determine whether a separately described definitive procedure is also reportable.

Can modifier 50 be used for bilateral work?

No. CMS identifies bilateral adjustment as inapplicable to this code, so modifier 50 is inappropriate.

What documentation supports reporting the transpetrosal approach?

Document the skull base route used, the exposure and bone work performed, and the operative target. The record should make clear why the approach was transpetrosal rather than another skull base corridor.

How does the 90-day global period affect postoperative billing?

The global period includes the day-before preoperative visit and 90 days of related postoperative care. Those services are included in the surgical global period.

Can an assistant or co-surgeon be reported?

Assistant-at-surgery payment may be available. Co-surgeon payment requires supporting documentation; team surgery is permitted.

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

Show the CMS file lines behind this rate
RVUs for 61598PPRRVU2026_Oct_nonQPP.csv, line 6,834 (RVU26D)

Open CMS sourceHow we calculate rates

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