Antibiotic susceptibility testing by a dilution method that finds the lowest drug concentration that stops an organism's growth, reported per plate or panel.
- Medicare
- $0.00
- Work RVU
- 0
- Global, days
- Region
- Multi-region
Documentation requirements
What must appear in the operative or office note to support the claim.
Source · Editorial brief grounded in 3 cited references ↓
- Organism identified and specimen source
- Number of panels or plates run
- Infection diagnosis under treatment
- Antibiotic selection based on MIC results
- Hardware or implant status if relevant to drug choice
Applicable modifiers
Modifiers commonly billed with this code.
Source · AMA CPT modifier descriptors · CMS NCCI Policy Manual
What this code covers
Source · Editorial summary grounded in 3 cited references ↓
87186 reports antibiotic susceptibility by microdilution or agar dilution. The lab exposes the organism to stepped concentrations of each antibiotic and reports the minimum inhibitory concentration (MIC). Most automated lab systems use this method, so it is more common on current claims than 87184.
In orthopedic infections, the MIC matters. Infectious disease uses it to pick between vancomycin, cefazolin, daptomycin, or an oral option for step-down therapy, and to judge whether rifampin can be added for retained hardware. The surgeon's note should show that the culture and susceptibility results changed or confirmed the plan.
Bill one unit per plate or panel as the lab reports it. Do not bill 87186 and 87184 for the same organism and drug panel unless the lab actually ran both for a documented reason. Susceptibility codes are billed on top of culture and identification. Payers flag high units, so the lab report has to show each panel run.
RVU & reimbursement
Component RVUs and Medicare national rate. Actual payment varies by GPCI locality.
Source · CMS Physician Fee Schedule, RVU26A · January 2026
| Work RVU | 0 |
| Practice expense RVU | 0 |
| Malpractice RVU | 0 |
| Total RVU | 0 |
| Medicare national rate | $0.00 |
| Global period | days |
Payment by site of service
Medicare pays different rates by setting. HOPD typically pays substantially more than ASC for the same procedure.
Source · CMS OPPS Addendum B·ASC HCPCS payment rates·2026
| Setting | Medicare rate (national) |
|---|---|
Office (PFS non-facility) Procedure performed in physician's office | $0.00 |
Common denial reasons
The recurring reasons claims for CPT 87186 get rejected.
Source · Editorial brief grounded in CMS NCCI edits, AAOS coding appeals, and cited references ↓
- Billed with 87184 for the same organism without explanation
- Units exceed panels on the lab report
- Culture code missing from the claim
- Billed by the ordering practice instead of the lab
- Repeat testing without modifier 91 or a documented reason
Frequently asked questions
Source · Generated from the editorial pipeline, verified against 3 cited references ↓
01What does MIC mean on a susceptibility report?
02Can 87186 be billed per antibiotic?
03Can 87184 and 87186 be billed together?
Sources & references
Editorial content was developed using the following public sources.
- 01CMS Physician Fee Schedule 2026
- 02CMS Clinical Laboratory Fee Schedule 2026
- 03cms.govhttps://www.cms.gov/medicare/coding-billing/national-correct-coding-initiative-ncci-edits
Mira Scribe
Mira Scribe captures the antibiotic discussion and hardware status the surgeon reviews, so the susceptibility results connect to a documented treatment plan.
See how Mira captures CPT 87186 documentation