CPT code 87186: Susceptibility test, microdilution or agar dilution2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Reports phenotypic antimicrobial susceptibility testing by microdilution or agar dilution, producing an MIC or breakpoint result for a cultured microorganism.
Medicare pays $8.65 for 87186 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
$8.65
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 87186 covers
An antimicrobial dilution susceptibility study tests a cultured microorganism against multiple antimicrobial agents using microdilution or agar-dilution methods. The laboratory evaluates growth to determine an MIC or apply a breakpoint interpretation. Clinical microbiology laboratories in hospitals and independent laboratories perform the work on isolates recovered through diagnostic culture when a clinician needs evidence about which antimicrobial options are active. The result supports selection or adjustment of treatment and is distinct from identifying the organism itself.
Report the service per plate, consistent with the multi-antimicrobial plate described for this method. Medicare pays 87186 under the CLFS at one national amount in every locality, without geographic or office-versus-facility adjustment. The 2026 national CLFS amount is $8.65, unchanged from 2020 through 2025. The test is paid 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 87186
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 87186. 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 87186 with status X (excluded by statute), so the test itself is paid only from the CLFS.
87186 on the lab fee schedule since 2020
87186 · CLFS 2026 Q4 (current)
$8.65
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.
87186 compared with similar tests
- 87181Agar susceptibilityPer antimicrobial agent$4.75
- Choose 87186 for a multi-antimicrobial dilution plate; 87181 represents agar-dilution susceptibility testing per antimicrobial agent.
- 87184Disk susceptibilityUp to 12 agents per plate$7.48
- 87184 is the disk method. 87186 is used when susceptibility is evaluated by microdilution or agar dilution.
- 87187MLC susceptibilityMicrodilution or agar dilution$40.17
- 87186 reports an MIC or breakpoint-based susceptibility result. 87187 is for dilution testing with a minimum lethal concentration endpoint.
- 87188Susceptibility testMacrobroth dilution method$6.64
- 87188 identifies the macrobroth dilution method; 87186 covers microdilution or agar dilution.
87186 billing questions
When should 87186 be used instead of 87184?
Use 87186 for dilution-based susceptibility testing by microdilution or agar dilution. Code 87184 describes the disk method.
How does 87186 differ from 87181?
87186 is for a multi-antimicrobial dilution plate. Code 87181 is for agar-dilution susceptibility testing reported per antimicrobial agent.
How are units counted?
The service is reported per plate. The code’s basis is the multi-antimicrobial plate, rather than a separate unit for every antimicrobial on it.
Does 87186 identify the microorganism?
No. It reports susceptibility testing of a cultured microorganism; organism identification is a separate laboratory service when performed and appropriately coded.
Does Medicare payment vary by location or setting?
No. Medicare pays one national CLFS amount in every state and locality, with no geographic or office-versus-facility adjustment.
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
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