CPT code 88373: ISH analysis, computer-assisted morphometry2026 Medicare rate & RVUs in California
Computer-assisted morphometric analysis quantifies or semi-quantifies in situ hybridization findings, such as signal patterns evaluated in tumor tissue.
Medicare pays $67.86–$84.89 for 88373 in the office in California, from Chico, CA to San Benito County, CA. Which amount applies depends on the service address.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
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On this page 9 sections
What 88373 covers
This service uses computer-assisted image analysis to quantify or semi-quantify findings from in situ hybridization (ISH) in a tissue specimen. A pathologist or qualified laboratory professional typically evaluates stained slides with imaging equipment and analysis software. A familiar clinical setting is assessment of HER2-related signals in breast carcinoma tissue; the method applies when the requested ISH findings require morphometric measurement rather than a qualitative read alone.
Select the service based on the computer-assisted morphometric method and the documented assay and specimen. The record should identify the tissue examined, probe or assay, analysis method, measured findings, and resulting interpretation. CMS treats 88373 as an add-on code: report it only with a primary procedure, and payment falls within that procedure’s global period. The service has separately priced professional and technical components: modifier 26 identifies interpretation, modifier TC identifies equipment and staff, and no component modifier represents the global service.
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 88373 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 payment localities
$67.86 to $84.89
29 of 29 payment localities
| Payment locality | Office | Facility |
|---|---|---|
| Bakersfield, CA | $67.93 | Unavailable |
| Chico, CA | $67.86 | Unavailable |
| El Centro, CA | $67.86 | Unavailable |
| Fresno, CA | $67.86 | Unavailable |
| Hanford, CA | $67.86 | Unavailable |
| Los Angeles, CA | $72.20 | Unavailable |
| Madera, CA | $67.86 | Unavailable |
| Marin County, CA | $83.17 | Unavailable |
| Merced, CA | $67.86 | Unavailable |
| Modesto, CA | $67.86 | Unavailable |
| Napa, CA | $78.52 | Unavailable |
| Oxnard, CA | $71.89 | Unavailable |
| Redding, CA | $67.86 | Unavailable |
| Rest of California | $67.86 | Unavailable |
| Riverside, CA | $67.99 | Unavailable |
| Sacramento, CA | $71.18 | Unavailable |
| Salinas, CA | $70.91 | Unavailable |
| San Benito County, CA | $84.89 | Unavailable |
| San Diego, CA | $72.52 | Unavailable |
| San Francisco, CA | $83.15 | Unavailable |
| San Luis Obispo, CA | $69.76 | Unavailable |
| Santa Clara County, CA | $84.84 | Unavailable |
| Santa Cruz, CA | $73.19 | Unavailable |
| Santa Maria, CA | $71.16 | Unavailable |
| Santa Rosa, CA | $73.93 | Unavailable |
| Stockton, CA | $67.86 | Unavailable |
| Vallejo, CA | $78.50 | Unavailable |
| Visalia, CA | $67.86 | Unavailable |
| Yuba City, CA | $67.86 | Unavailable |
How the 88373 rate is calculated
Each of 88373’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 · 88373
RVUs × geographic indexes × conversion factor
Work0.57
0.57 RVUs× 1.000 GPCI
Practice expense1.32
1.32 RVUs× 1.000 GPCI
Malpractice0.01
0.01 RVUs× 1.000 GPCI
Adjusted RVUs
1.9000
Conversion factor
$33.4009
Medicare rate
$63.46
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 88373
The CMS indicators that decide how 88373 is paid alongside other services.
CMS payment indicators · 88373
ISH analysis, computer-assisted morphometry
| Rule | CMS value | What it means |
|---|---|---|
| Global period | ZZZ | Add-on code: falls within the primary procedure’s global period. |
| Multiple procedures | 0 | No multiple-procedure reduction. |
| Bilateral (modifier 50) | 0 | The 150% bilateral adjustment doesn’t apply. |
| Assistant at surgery (80/81/82/AS) | 0 | Not paid without supporting documentation. |
| Co-surgeons (62) | 0 | Not permitted. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 1 | Diagnostic test with separate professional (26) and technical (TC) components. |
What modifiers do to the payment
Modifier 26 · payment effect
With and without the modifier
88373 without 26 · national office
$63.46
ISH analysis, computer-assisted morphometry
88373-26 · Professional component
$23.71
Pays only the interpretation and report.
88373 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 88369ISH morphometryQuantitative or semiquantitative
- Choose 88373 for computer-assisted morphometric ISH analysis; 88369 represents manual morphometric analysis.
- 88367ISH analysisAutomated morphometric analysis
- 88367 represents automated ISH. 88373 is distinguished by quantitative or semi-quantitative morphometric analysis using computer-assisted technology.
- 88361Tumor immunohistochemistryComputer-assisted analysis
- 88361 is computer-assisted tumor immunohistochemistry analysis. 88373 concerns morphometric analysis of ISH findings, a different assay.
88373 billing questions
How does 88373 differ from 88369?
88373 is for computer-assisted morphometric analysis of ISH findings. Use 88369 when the morphometric analysis is performed manually.
Can 88373 be reported by itself?
No. CMS identifies it as an add-on code, so it must be reported with a primary procedure. Payment is within that primary procedure’s global period.
When should modifier 26 or TC be used?
Use modifier 26 for the professional interpretation and modifier TC for the technical service, including equipment and staff. Report the global service without either component modifier.
What documentation supports 88373?
Document the specimen, ISH assay or probe, use of computer-assisted morphometric analysis, measured findings, and interpretation. The record should make clear that the work was quantitative or semi-quantitative.
Is this the same as automated ISH?
Not necessarily. 88373 describes computer-assisted morphometric measurement; an ISH service without that morphometric analysis may be represented by a different code.
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.
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