Lab & pathology
87186 — Susceptibility studies, antimicrobial agent; MIC, each multi-antimicrobial, agar dilution method
An antibiotic sensitivity test performed on bacteria already grown from a culture, where the lab tests the bacteria against multiple antibiotics to find out which medications will effectively kill them.
- Typical setting: Hospital lab, reference lab
- National avg charge (illustrative): $8–$20 Medicare allowed (CMS CLFS); $15–$60 commercial; varies by region
- Most-disputed reason: Billing 87186 without a prior positive culture (87070, 87086, or blood culture) — sensitivity studies can only be performed on an isolated organism
What it means
What 87186 actually means
An antibiotic sensitivity test performed on bacteria already grown from a culture, where the lab tests the bacteria against multiple antibiotics to find out which medications will effectively kill them. The results (reported as susceptible, intermediate, or resistant) guide the doctor in choosing the right antibiotic treatment.
Common errors with this code
What goes wrong on real bills.
Most bills that look correct still contain at least one of these issues. Up to 49% of medical bills contain errors (CFPB).
- Billing 87186 without a prior positive culture (87070, 87086, or blood culture) — sensitivity studies can only be performed on an isolated organism
- Billing 87186 multiple times for the same isolate against different antibiotic panels without documentation that additional testing was separately ordered and performed
- Confusing 87186 (MIC dilution method) with 87184 (disk diffusion/Kirby-Bauer) — these are different susceptibility methods with different codes
If you see 87186 on your bill
Three steps before paying.
1. Get the itemized bill. If your statement only shows a summary, request the CPT-level itemized bill before paying. Generate the request language →
2. Cross-check against the EOB. Compare what your insurer's Explanation of Benefits says you owe versus what the hospital is asking. They disagree more often than people think. Read the bill-vs-EOB guide →
3. Run a free Bill Scan. Upload the bill (and EOB if you have it) and BillBusted will flag the most likely issues with this specific code in your specific state. Run free scan →
Related codes
Other codes in this category.
People who land on 87186 often also see these adjacent codes on the same bill.
CPT
80050 — General health panel; includes CBC w/diff, CMP, TSH
Lab — check for unbundling and duplicate billing.
CPT
80051 — Electrolyte panel; CO2, chloride, potassium, sodium
Lab — check for unbundling and duplicate billing.
CPT
80053 — Comprehensive metabolic panel
If individual blood tests are also on your bill, you may have an unbundling error.
CPT
80055 — Obstetric panel; CBC w/diff, HBsAg, rubella Ab, syphilis, RBC Ab screen, ABO/Rh
Lab — check for unbundling and duplicate billing.
CPT
80061 — Lipid panel (cholesterol)
If you see HDL or LDL listed separately next to 80061, that's unbundling.
Related BillBusted guides
Plain-English reads if you see 87186 on a bill.
87186 FAQ
Plain-English answers.
What does 87186 usually cost?
$8–$20 Medicare allowed (CMS CLFS); $15–$60 commercial; varies by region. Costs vary by region, payer contract, and whether the service was performed in a hospital outpatient department (which adds a facility fee) versus a free-standing clinic.
What's the most common billing error on 87186?
Billing 87186 without a prior positive culture (87070, 87086, or blood culture) — sensitivity studies can only be performed on an isolated organism
What should I do if I see 87186 on my bill?
Request the itemized bill and the matching EOB from your insurer. Compare the units/quantity billed against what you actually received. Run a free BillBusted scan to flag the most likely errors specific to 87186 before paying.
Don't pay 87186 blindly.
The free scan tells you in under 60 seconds whether this charge looks reasonable for your situation.