CPT code 87188: Susceptibility test, macrobroth dilution method2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Macrobroth dilution susceptibility testing evaluates an isolate’s response to an antimicrobial agent and is reported for each agent tested.
Medicare pays $6.64 for 87188 under the 2026 Clinical Laboratory Fee Schedule: one national amount, the same in every state and setting.
Medicare lab fee · CLFS 2026 Q4
National CLFS amount
$6.64
In effect since Jan 1, 2026. The same amount in every state, payment locality and setting.
- Geographic adjustment
- None
- Office vs facility
- Same
- Since 2020
- Unchanged
- CMS updates
- Quarterly
Medicare pays the lesser of the lab’s charge and this amount. Patients usually owe no Part B deductible or coinsurance for covered clinical lab tests.
On this page 8 sections
What 87188 covers
Macrobroth dilution testing assesses an organism’s response to an antimicrobial agent by testing the isolate in broth at a range of concentrations. The agent may be an antibiotic, antifungal, or antiviral drug. Results can help guide antimicrobial selection for an infection. Clinical microbiology laboratories perform this test on cultured isolates and report susceptibility results for each agent tested.
Report one unit for each antimicrobial agent tested by this method. Medicare pays 87188 through the CLFS at one nationally set amount that applies across states and localities, with no geographic or office/facility adjustment. The 2026 national amount is $6.64, unchanged since 2020. The service is paid only through the CLFS and is excluded from the physician fee schedule.
This summary was written with AI assistance from CMS Clinical Laboratory Fee Schedule data. Amounts on this page come directly from CMS files.
How Medicare pays 87188
Clinical lab tests aren’t priced like physician services. They’re paid from their own fee schedule, with its own rules. See the whole lab fee schedule.
One national amount
CMS sets a single Clinical Laboratory Fee Schedule amount for 87188. There’s no geographic (GPCI) adjustment, so it pays the same in every state and payment locality.
No office or facility rate
Lab tests aren’t built from relative value units, so there’s no office and facility split: the place of service doesn’t change the CLFS amount.
Updated every quarter
CMS republishes the CLFS each quarter. New tests, often proprietary laboratory analyses (PLA codes), join during the year; existing amounts are updated each January.
Excluded from the physician fee schedule
The physician fee schedule lists 87188 with status X (excluded by statute), so the test itself is paid only from the CLFS.
87188 on the lab fee schedule since 2020
87188 · CLFS 2026 Q4 (current)
$6.64
Unchanged since Jan 1, 2020
27 quarterly CLFS releases on file, first CLFS 2020 Q1. A code missing from a quarter wasn’t on that release.
87188 compared with similar tests
- 87181Agar susceptibilityPer antimicrobial agent$4.75
- Choose 87188 for macrobroth dilution and 87181 for agar dilution. Both describe susceptibility testing by antimicrobial agent.
- 87184Disk susceptibilityUp to 12 agents per plate$7.48
- 87184 is for disk-method susceptibility testing, reported per plate. Use 87188 for macrobroth dilution, reported per agent.
- 87186Susceptibility testMicrodilution or agar dilution$8.65
- 87186 covers microdilution or agar dilution; 87188 identifies macrobroth dilution. Select the code that matches the method performed.
- 87187MLC susceptibilityMicrodilution or agar dilution$40.17
- 87187 describes minimum lethal concentration testing by microdilution or agar dilution. 87188 describes macrobroth dilution susceptibility testing.
87188 billing questions
When should 87188 be reported instead of 87186?
Use 87188 when the susceptibility study uses macrobroth dilution. Code 87186 describes microdilution or agar dilution testing.
How many units should be reported?
Report one unit for each antimicrobial agent tested by macrobroth dilution.
Is 87188 reported for the culture itself?
No. It reports the susceptibility study for an antimicrobial agent, not the culture or organism identification.
How does Medicare pay for 87188?
Medicare pays the service through the CLFS at one national amount, with no geographic or office-versus-facility adjustment. It is excluded from the physician fee schedule.
What should the laboratory record to support this code?
The laboratory record should identify the antimicrobial agent tested and show that macrobroth dilution was the method used.
Where this amount comes from
FeeBase reads lab amounts directly from the CMS Clinical Laboratory Fee Schedule file for the quarter: one row per code, with its payment indicator and national amount. Contractor-priced tests are labeled, never given a made-up amount. Amounts are Medicare payment limits, not a patient’s bill or a commercial rate.
CMS CLFS 2026 Q4 · effective Oct 1, 2026 through the day before Jan 1, 2027
Show the CMS file line behind this amount
Fee sheets
Put 87188 and the rest of your codes on one sheet
Your codes at your locality, with payer contracts beside Medicare.
Build my fee sheet