CPT code 88364: ISH probe stain, each additional probe2026 Medicare rate & RVUs in Merced, CA

Reports an additional single-probe in situ hybridization stain on a specimen after the initial probe procedure, such as an additional FISH probe.

CMS RVU26DEffective Oct 1, 2026One payment locality47.5K Medicare services in 2024

In Merced, CA, Medicare pays $136.57 for 88364 in the office.

$136.57Office (non-facility)
Not available in this settingHospital or facility
+7.9%vs the national office rate ($126.59)

Check a contract rate as a % of Medicare · 88364 nationwide

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

We’ll open 88364 for the payment locality that covers the ZIP.

On this page 11 sections
  1. Rate in Merced, CA
  2. What 88364 covers
  3. Compared with other areas
  4. Rate map
  5. How it’s calculated
  6. Payment rules
  7. Related codes
  8. Rate history
  9. Where it applies
  10. Billing questions
  11. Sources

What 88364 covers

This code covers an additional single-probe in situ hybridization stain procedure on a specimen after its initial probe stain. A pathology laboratory performs the probe-based testing on tissue or other submitted material, and a pathologist interprets the findings as part of the diagnostic workup. Fluorescence in situ hybridization (FISH) is a familiar example; the additional stain may assess another target on the specimen.

Report the code only with an eligible primary procedure, such as the initial single-probe stain, and count each additional probe stain procedure per specimen. The record should identify the specimen, the additional probe or target, and the testing performed. Medicare treats this as an add-on paid within the primary procedure’s global period. The global service is billed without a component modifier; modifier 26 reports the interpretation, while modifier TC reports the technical work, equipment, and staff. Both modifiers are separately priced.

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.

How Merced, CA compares for 88364

Across 109 of 109 payment localities, the office rate for 88364 runs from $111.71 in Arkansas to $174.40 in San Benito County, CA. Merced, CA pays $136.57. The RVUs are the same everywhere; the geographic indexes change the dollars.

88364 in Merced, CA vs other payment areas
  1. Merced, CA · this page$136.57
  2. Bakersfield, CA · California$136.67+$0.10
  3. Chico, CA · California$136.57
  4. El Centro, CA · California$136.58+$0.01
  5. Fresno, CA · California$136.57
  6. Hanford, CA · California$136.57
  7. Los Angeles, CA · California$146.18+$9.61

Other areas in California first, then benchmark localities. Bars start at $0.

Every other payment area

88364 in every other Medicare payment locality
Payment localityOfficeFacility
Madera, CACalifornia$136.57—
Modesto, CACalifornia$136.57—
Napa, CACalifornia$160.51—
Oxnard, CACalifornia$145.76—
Redding, CACalifornia$136.57—
Rest of CaliforniaCalifornia$136.57—
Riverside, CACalifornia$136.81—
Sacramento, CACalifornia$143.92—

88364 rates by state

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

Explore a state

Local rates. Clear comparisons.

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

$111.71

$155.49

Color shows the midpoint of each state’s locality range.

View every state and territory as a table
88364 office rate range by state
State / territoryOffice rate rangeLocalities
AK$144.351
AL$113.401
AR$111.711
AZ$123.291
CA$136.57–$174.4029
CO$133.321
CT$135.131
DC$146.261
DE$125.401
FL$122.38–$131.843
GA$115.57–$128.442
GU$140.451
HI$140.451
IA$117.411
ID$117.981
IL$117.99–$130.054
IN$118.711
KS$116.351
KY$115.081
LA$114.69–$120.592
MA$132.29–$147.472
MD$128.00–$146.263
ME$118.08–$125.412
MI$117.70–$123.442
MN$129.111
MO$112.33–$121.643
MS$112.071
MT$126.591
NC$119.431
ND$126.191
NE$118.231
NH$130.741
NJ$137.06–$144.582
NM$118.161
NV$126.581
NY$121.23–$148.125
OH$117.621
OK$115.401
OR$125.98–$138.242
PA$118.09–$131.362
PR$127.711
RI$130.351
SC$118.651
SD$126.151
TN$116.891
TX$117.25–$132.548
UT$120.331
VA$124.64–$146.262
VI$127.711
VT$125.231
WA$132.20–$151.032
WI$121.791
WV$113.361
WY$126.421

See 88364 in every payment locality

How the 88364 rate is calculated

Each of 88364’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 · 88364

RVUs × geographic indexes × conversion factor

Office or facility?

Work0.68

0.68 RVUs× 1.000 GPCI

Practice expense3.09

3.09 RVUs× 1.000 GPCI

Malpractice0.02

0.02 RVUs× 1.000 GPCI

Adjusted RVUs

3.7900

Conversion factor

$33.4009

Medicare rate

$126.59

Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.

The exact Merced, CA inputs and CMS source lines

PPRRVU2026_Oct_nonQPP.csv

11,285

Code
88364
Physician work
0.68
Practice expense
3.09
Malpractice
0.02

GPCI2026.csv

15

Locality
Merced, CA
Physician work
1.017
Practice expense
1.096
Malpractice
0.536
Office calculation for 88364 in Merced, CA
ComponentRVULocality factorAdjusted
Physician work0.68× 1.0170.6916
Practice expense3.09× 1.0963.3866
Malpractice0.02× 0.5360.0107
Total RVUs4.0889
Conversion factor× 33.4009

Office rate, Merced, CA$136.57

Office: (0.68 × 1.017 + 3.09 × 1.096 + 0.02 × 0.536) × $33.4009 = $136.57

Open 88364 in the RVU calculator

Payment rules and modifiers for 88364

The CMS indicators that decide how 88364 is paid alongside other services.

CMS payment indicators · 88364

ISH probe stain, each additional probe

RuleCMS valueWhat it means
Global periodZZZAdd-on code: falls within the primary procedure’s global period.
Multiple procedures0No multiple-procedure reduction.
Bilateral (modifier 50)0The 150% bilateral adjustment doesn’t apply.
Assistant at surgery (80/81/82/AS)0Not paid without supporting documentation.
Co-surgeons (62)0Not permitted.
Team surgery (66)0Not permitted.
Professional/technical1Diagnostic test with separate professional (26) and technical (TC) components.

What modifiers do to the payment

Modifier 26 · payment effect

With and without the modifier

88364 without 26 · national office

$126.59

ISH probe stain, each additional probe

88364-26 · Professional component

$31.73

Pays only the interpretation and report.

When to use modifier 26

How 88364 has changed in Merced, CA

88364 · Office / nonfacility

$136.57

Effective 2026-10-01

The base rate is $1.88 higher than on 2025-10-01, moving from $134.69 to $136.57 (1.4%).

It is unchanged from the immediately preceding available release, effective 2026-07-01.

Base rate by release · bars start at $0 · select a bar to compare

One bar per available release, ordered by effective date. Missing rates remain gaps. These comparisons hold the code, setting and locality identifiers constant; they do not isolate which policy or input caused a change.

What changed, release by release
  1. January 1, 2026

    RVU26A

    $134.69changed to$136.57

    • Conversion factor 32.3465 changed to 33.4009
    • Work RVU 0.70 changed to 0.68
    • Practice expense RVU 3.15 changed to 3.09
    • Work GPCI 1.014 changed to 1.017
    • Practice expense GPCI 1.093 changed to 1.096
    • Malpractice GPCI 0.560 changed to 0.536

    Held through RVU26B, RVU26C, RVU26D.

  2. January 1, 2025

    RVU25A

    $143.34changed to$134.69

    • Conversion factor 33.2875 changed to 32.3465
    • Practice expense RVU 3.28 changed to 3.15

    Held through RVU25B, RVU25C, RVU25D.

  3. March 9, 2024

    RVU24AR

    $141.00changed to$143.34

    • Conversion factor 32.7442 changed to 33.2875

    Held through RVU24B, RVU24C, RVU24D.

  4. January 1, 2024

    RVU24A

    $147.10changed to$141.00

    • Conversion factor 33.8872 changed to 32.7442
    • Practice expense RVU 3.35 changed to 3.28
    • Work GPCI 1.021 changed to 1.014
    • Practice expense GPCI 1.079 changed to 1.093
    • Malpractice GPCI 0.579 changed to 0.560
  5. January 1, 2023

    RVU23A

    $148.02changed to$147.10

    • Conversion factor 34.6062 changed to 33.8872
    • Practice expense RVU 3.33 changed to 3.35
    • Work GPCI 1.027 changed to 1.021
    • Practice expense GPCI 1.065 changed to 1.079
    • Malpractice GPCI 0.597 changed to 0.579

    Held through RVU23B, RVU23C, RVU23D.

  6. January 1, 2022

    RVU22A

    $152.59changed to$148.02

    • Conversion factor 34.8931 changed to 34.6062
    • Practice expense RVU 3.42 changed to 3.33

    Held through RVU22B, RVU22C, RVU22D.

  7. January 1, 2021

    RVU21A

    $148.70changed to$152.59

    • Conversion factor 36.0896 changed to 34.8931
    • Practice expense RVU 3.17 changed to 3.42
    • Work GPCI 1.024 changed to 1.027
    • Practice expense GPCI 1.070 changed to 1.065
    • Malpractice GPCI 0.580 changed to 0.597

    Held through RVU21B, RVU21C, RVU21D.

  8. January 1, 2020

    RVU20A

    $142.84changed to$148.70

    • Conversion factor 36.0391 changed to 36.0896
    • Practice expense RVU 3.01 changed to 3.17
    • Malpractice RVU 0.03 changed to 0.02
    • Work GPCI 1.020 changed to 1.024
    • Practice expense GPCI 1.074 changed to 1.070
    • Malpractice GPCI 0.562 changed to 0.580

    Held through RVU20B, RVU20C, RVU20D.

  9. January 1, 2019

    RVU19A

    $143.07changed to$142.84

    • Conversion factor 35.9996 changed to 36.0391
    • Practice expense RVU 3.02 changed to 3.01

    Held through RVU19B, RVU19C, RVU19D.

  10. January 1, 2018

    RVU18AR1

    $141.78changed to$143.07

    • Conversion factor 35.8887 changed to 35.9996
    • Practice expense RVU 2.98 changed to 3.02
    • Work GPCI 1.024 changed to 1.020
    • Practice expense GPCI 1.079 changed to 1.074
    • Malpractice GPCI 0.610 changed to 0.562

    Held through RVU18B, RVU18C, RVU18D.

  11. January 1, 2017

    RVU17A

    No ratechanged to$141.78

    Held through RVU17B, RVU17C, RVU17D.

  12. January 1, 2015

    RVU15A

    No ratechanged toNo rate

    Held through RVU15B, RVU15C, RVU15D, RVU16A, RVU16B, RVU16C, RVU16D.

  13. January 1, 2013

    RVU13AR

    Earliest loaded release: No rate

    Held through RVU13B, RVU13C, RVU13D, RVU14A, RVU14B, RVU14C, RVU14D.

Rates in every CMS release
Effective fromOfficeFacilityCMS release
2026-10-01$136.57Not available in this settingRVU26D
2026-07-01$136.57Not available in this settingRVU26C
2026-04-01$136.57Not available in this settingRVU26B
2026-01-01$136.57Not available in this settingRVU26A
2025-10-01$134.69Not available in this settingRVU25D
2025-07-01$134.69Not available in this settingRVU25C
2025-04-01$134.69Not available in this settingRVU25B
2025-01-01$134.69Not available in this settingRVU25A
2024-10-01$143.34Not available in this settingRVU24D
2024-07-01$143.34Not available in this settingRVU24C
2024-04-01$143.34Not available in this settingRVU24B
2024-03-09$143.34Not available in this settingRVU24AR
2024-01-01$141.00Not available in this settingRVU24A
2023-10-01$147.10Not available in this settingRVU23D
2023-07-01$147.10Not available in this settingRVU23C
2023-04-01$147.10Not available in this settingRVU23B
2023-01-01$147.10Not available in this settingRVU23A
2022-10-01$148.02Not available in this settingRVU22D
2022-07-01$148.02Not available in this settingRVU22C
2022-04-01$148.02Not available in this settingRVU22B
2022-01-01$148.02Not available in this settingRVU22A
2021-10-01$152.59Not available in this settingRVU21D
2021-07-01$152.59Not available in this settingRVU21C
2021-04-01$152.59Not available in this settingRVU21B
2021-01-01$152.59Not available in this settingRVU21A
2020-10-01$148.70Not available in this settingRVU20D
2020-07-01$148.70Not available in this settingRVU20C
2020-04-01$148.70Not available in this settingRVU20B
2020-01-01$148.70Not available in this settingRVU20A
2019-10-01$142.84Not available in this settingRVU19D
2019-07-01$142.84Not available in this settingRVU19C
2019-04-01$142.84Not available in this settingRVU19B
2019-01-01$142.84Not available in this settingRVU19A
2018-10-01$143.07Not available in this settingRVU18D
2018-07-01$143.07Not available in this settingRVU18C
2018-04-01$143.07Not available in this settingRVU18B
2018-01-01$143.07Not available in this settingRVU18AR1
2017-10-01$141.78Not available in this settingRVU17D
2017-07-01$141.78Not available in this settingRVU17C
2017-04-01$141.78Not available in this settingRVU17B
2017-01-01$141.78Not available in this settingRVU17A
2016-10-01Rate data unavailableNot available in this settingRVU16D
2016-07-01Rate data unavailableNot available in this settingRVU16C
2016-04-01Rate data unavailableNot available in this settingRVU16B
2016-01-01Rate data unavailableNot available in this settingRVU16A
2015-10-01Rate data unavailableNot available in this settingRVU15D
2015-07-01Rate data unavailableNot available in this settingRVU15C
2015-04-01Rate data unavailableNot available in this settingRVU15B
2015-01-01Rate data unavailableNot available in this settingRVU15A
2014-10-01Not in this releaseNot in this releaseRVU14D
2014-07-01Not in this releaseNot in this releaseRVU14C
2014-04-01Not in this releaseNot in this releaseRVU14B
2014-01-01Not in this releaseNot in this releaseRVU14A
2013-10-01Not in this releaseNot in this releaseRVU13D
2013-07-01Not in this releaseNot in this releaseRVU13C
2013-04-01Not in this releaseNot in this releaseRVU13B
2013-01-01Not in this releaseNot in this releaseRVU13AR

Price 88364 for an earlier date of service

Where the Merced, CA rate applies

Merced, CA is a Medicare payment area, not a city. Our Census mapping connects it to 24 cities and communities in California. Some span more than one payment area; confirm with the service ZIP.

  • Merced
  • Atwater
  • Ballico
  • Bear Creek
  • Cressey
  • Delhi
  • Dos Palos
  • Dos Palos Y

Browse all communities in California

88364 billing questions

When is this code used instead of the initial-probe code?

Use it for each additional single-probe stain procedure on a specimen after the initial probe procedure. The initial stain is reported with 88365.

Can this code be billed by itself?

No. It is an add-on code and must be reported with an eligible primary procedure, such as the initial probe stain.

How are units counted?

Count each additional single-probe stain procedure per specimen. Document the specimen and the additional probe or target tested.

When should modifier 26 or TC be used?

Use modifier 26 for the professional interpretation or TC for the technical work, equipment, and staff. Without either modifier, the claim represents the global service.

What documentation supports an additional-probe claim?

The record should show which specimen received testing, the additional probe or target, and that the service was an additional stain procedure beyond the initial probe.

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 88364PPRRVU2026_Oct_nonQPP.csv, line 11,285 (RVU26D)
Geographic factors for Merced, CAGPCI2026.csv, line 15 (RVU26D)

Open CMS sourceHow we calculate rates

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