CPT code 87075 – Anaerobic culture billing and coding

Key Takeaways

CPT code 87075 covers primary anaerobic culture only, any specimen except urine and blood

Gram stain (87205), isolate ID (87076), and susceptibility testing (87184/87186) are each separately billable

Missing ICD-10-CM diagnosis or undocumented specimen source are the top two denial triggers

Pabau’s claims management software links lab orders to diagnosis codes and flags missing documentation before submission

CPT code 87075: Official descriptor and procedure overview

CPT code 87075 is defined by the American Medical Association (AMA) as: Culture, bacterial; anaerobic isolate, additional methods required for definitive identification, each isolate. In practice, the code covers the full primary anaerobic culture process, from inoculation of the specimen into an anaerobic transport medium through incubation and detection of bacterial growth.

The two critical scope limits in the descriptor: Urine and blood are explicitly excluded. Urine cultures have dedicated codes (87086 and 87088). Blood cultures use 87040. Every other specimen source is covered by 87075 when the culture targets anaerobic organisms.

Appropriate specimen types for 87075:

• Wound swabs and wound tissue
• Abscess aspirate
• Deep tissue and surgical specimens
• Body fluids (pleural, peritoneal, synovial)
• Post-surgical infection specimens
• Respiratory specimens (excluding standard sputum, which has aerobic codes)

The ordering provider’s requisition must specify anaerobic culture, not simply “culture.” A requisition that reads “wound culture” without specifying anaerobic will often default to aerobic processing, and billing 87075 on a specimen processed only aerobically is unbillable.

What CPT 87075 includes and what it excludes

CPT 87075 covers the primary culture only: Inoculation, anaerobic incubation, and detection of growth. It does not cover any downstream testing or ancillary procedures performed on the same specimen.

NCCI (National Correct Coding Initiative) edits govern bundling between 87075 and certain companion codes. Because NCCI edit tables are updated quarterly, always verify the current edit pairs at the CMS NCCI policy page before billing. A modifier 59 may be required when billing 87075 alongside 87070 on the same claim if both cultures were ordered from the same specimen for distinct clinical reasons.

CPT 87075 vs. CPT 87070: Aerobic vs. anaerobic differences

CPT 87070 covers aerobic bacterial culture from any source except urine and blood. CPT 87075 covers the same specimen scope but specifically targets organisms that grow only in oxygen-free environments. The two codes are frequently confused when a lab processes both aerobic and anaerobic cultures from the same wound specimen.

When both are billed on the same date from the same specimen, the claim must clearly show that the ordering provider requisitioned both aerobic and anaerobic cultures. A single “wound culture” order without specifying both does not support two charges.

Related microbiology codes: 87076, 87077, and beyond

The codes most frequently used alongside CPT code 87075 form a tight cluster in the 87000-series. Understanding their billing relationships prevents both underbilling (missed add-ons) and overbilling (incorrect bundling).

87076 is the most commonly missed add-on. When an anaerobic culture returns two distinct isolates requiring separate identification, 87075 covers the first and 87076 is reported once per additional isolate. Some coders assume the primary culture code covers all isolates, leaving legitimate charges on the table. See the AAPC Codify CPT lookup for the full descriptor and billing notes for each code in this cluster.

How the anaerobic culture procedure works: Clinical steps for accurate coding

Understanding what happens in the lab is the fastest way to identify what must be documented to support a charge. Each clinical step maps directly to a documentation requirement on the claim.

1. Specimen collection: Clinician collects from the appropriate anatomic site. Transport must use an anaerobic transport vial or port-a-cul system to preserve anaerobic viability. A regular swab exposed to oxygen invalidates anaerobic culture.
2. Specimen receipt and labeling: Lab receives the specimen with the ordering provider’s name, collection date and time, anatomic source, and test ordered (anaerobic culture). Missing source or collection time creates documentation gaps that payers flag.
3. Inoculation: Specimen is inoculated onto anaerobic agar plates and placed in an anaerobic incubation jar or chamber.
4. Incubation: Cultures are incubated for 48 to 72 hours under oxygen-free conditions. Some slow-growing anaerobes require up to five days.
5. Growth detection and isolation: Tech examines plates for bacterial growth. This step completes the work covered by 87075. Each distinct morphology is subcultured for identification.
6. Isolate identification (separately billed): When additional identification methods are required for each distinct organism isolated, 87076 is reported for each additional isolate beyond the first.

The charge for CPT code 87075 is fully supported by documentation of steps one through five. If the lab report does not show collection source, collection date, organism result (even “no growth”), and the ordering provider, the claim is vulnerable.

Documentation requirements for billing CPT 87075

Every element below must appear in the medical record and be reflected on the claim. Missing any single element is sufficient for a payer to deny the charge. Understanding medical billing basics helps practices structure lab requisitions to capture these fields consistently from the point of order.

• Ordering provider: Full name and NPI of the ordering physician or other qualified provider. Claims submitted without an ordering provider NPI are rejected at the clearinghouse level on most payers.
• Diagnosis (ICD-10-CM): At least one diagnosis code that supports the medical necessity of anaerobic culture. The diagnosis must be on the payer’s covered ICD-10 list; check your MAC’s Local Coverage Determination (LCD).
• Specimen source: The specific anatomic site. “Wound” alone is insufficient; “left foot plantar wound” is acceptable. The source must match the specimen type in the lab result.
• Collection date and time: Required for timely filing and for Medicare claims processing. Date alone is typically sufficient unless modifier 91 applies (same-day repeat).
• Anaerobic culture ordered explicitly: The requisition or order must state anaerobic culture. A generic “culture” order does not automatically qualify for 87075.
• Test result: Lab report showing organism growth or “no growth.” Result must be in the chart; billing before the result is in the record is premature.

Pabau’s claims management software links the ordering provider, ICD-10 diagnosis, and specimen details at the point of order entry, reducing the documentation gaps that drive anaerobic culture denials. For practices managing high lab volumes, automating this link before the specimen even reaches the lab is where compliance risk drops most sharply. See medical billing compliance guidance for a broader framework.

Medicare coverage and reimbursement for CPT 87075

CPT code 87075 is covered by Medicare under the Clinical Laboratory Fee Schedule (CLFS). The CLFS sets a national limitation amount for lab codes, and that amount is updated annually each January. Because the rate changes year to year, always verify the current allowable at the CMS Clinical Laboratory Fee Schedule lookup tool rather than relying on a figure stated in a guide like this one. The Centers for Medicare and Medicaid Services (CMS) publishes the annual CLFS on the CMS website, usually in November for the following year.

Coverage under Medicare is conditional on medical necessity. Coverage is not automatic simply because the code is on the CLFS. The ordering provider must document a diagnosis that links to an applicable LCD from the Medicare Administrative Contractor (MAC) covering the lab’s jurisdiction. MACs such as Palmetto GBA, Novitas, and CGS each publish their own LCDs for microbiology testing. If the submitted ICD-10-CM code is not on the LCD’s covered-diagnosis list, Medicare will deny the claim as not medically necessary.

When medical necessity may not be met, the lab must issue an Advance Beneficiary Notice (ABN) before performing the test. Without an ABN, the lab cannot bill the beneficiary if Medicare denies. The ABN requirement applies to all CLFS-covered services that the lab has reason to believe may not be covered. Submit claims via your Pabau Claim.MD clearinghouse integration, which routes 837P claims to over 4,000 US payers, including all Medicare Administrative Contractors, and returns ERAs so denials are visible in one place.

CPT 87075 reimbursement: Commercial payer considerations

Commercial payers handle CPT code 87075 reimbursement differently from Medicare in three key ways.

• Contracted vs. non-contracted rates: Commercial payer allowables for 87075 vary significantly from the Medicare CLFS rate. In-network labs receive contracted rates; non-contracted labs may bill charges but are subject to balance-billing restrictions in some states.
• Prior authorization: Some commercial plans require prior authorization for outpatient lab orders, particularly for non-urgent anaerobic cultures. Confirm payer-specific requirements before the specimen is collected.
• Medicaid variability: Medicaid coverage and reimbursement for anaerobic culture varies by state. Some state Medicaid programs mirror Medicare’s CLFS; others set independent rates or have different covered-diagnosis requirements. Verify with the specific state program.
• Documentation expectations: Commercial payers often mirror Medicare’s documentation requirements but may add their own medical necessity criteria. Some require the ordering provider to be enrolled with the payer, not just licensed in the state.

For practices dealing with multiple payer contracts, understanding superbill documentation that captures the right fields consistently across payers saves significant rework at the billing stage.

Manage lab billing workflows without the documentation gaps

Pabau connects lab orders to ICD-10 diagnoses, ordering provider details, and claim submission in one workflow. See how practices reduce anaerobic culture denials with linked documentation.

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Common denial reasons for CPT 87075 and how to avoid them

Revenue cycle teams flag a consistent set of denial triggers on anaerobic culture claims. Understanding denial management workflows for lab codes starts with knowing which triggers account for the highest volume.

The clean-claim framework applies directly here: Submitting a clean claim for anaerobic culture means every required field passes payer edits before the claim reaches adjudication. Claims that fail clearinghouse edits on ordering provider NPI or diagnosis code never reach the payer, so the denial does not even appear in remittance data, making the problem invisible until an audit surfaces it.

ICD-10-CM codes commonly paired with CPT 87075

The ICD-10-CM diagnosis must support the medical necessity of anaerobic culture specifically. According to the CDC ICD-10-CM coding tool, the most clinically appropriate diagnoses for anaerobic culture requests map to infections where anaerobic organisms are known pathogens. LCD-covered diagnoses vary by MAC jurisdiction; the codes below represent the most commonly accepted categories, but always verify against your specific MAC’s current LCD before billing.

Non-specific codes such as Z00.00 (encounter for general adult medical examination) or symptom codes without an infection context will not support medical necessity for anaerobic culture under most LCDs. The diagnosis must reflect an active infection or a clinical condition in which anaerobic organisms are a recognized pathogen.

Place of service and modifier considerations for CPT 87075

Place of service (POS) codes affect reimbursement and claim routing for anaerobic culture charges. The two most common settings are POS 81 (independent laboratory) and POS 11 (office, when the practice has an in-house lab performing the culture). Using the wrong POS can trigger a denial even when all other claim elements are correct.

• POS 81 (independent laboratory): Used when a freestanding or reference lab performs the culture. The lab bills 87075 directly under its own NPI. This is the most common setting for high-volume anaerobic culture billing.
• POS 11 (office): Used only when the practice has an in-house CLIA-certified lab performing the culture. The practice bills under its own NPI. CLIA certification at the appropriate complexity level is required; without it, the claim is unbillable at POS 11.
• Modifier 91 (repeat clinical diagnostic laboratory test): Apply when the same anaerobic culture is repeated on the same day for the same patient for a clinically distinct reason. This modifier signals to the payer that the second charge is not a duplicate. Do not use modifier 91 when the repeat test results from equipment malfunction or when it confirms an earlier result for confirmation only.
• Modifier 59 (distinct procedural service): Apply when billing 87075 and 87070 from the same specimen on the same date, and an NCCI edit would otherwise bundle them. The modifier signals that each culture is a distinct, separately performed service. Always verify the current NCCI edit status before applying modifier 59; apply it per payer-specific guidance, not as a blanket workaround.

CLIA certification is a hard requirement for in-house lab billing. The Clinical Laboratory Improvement Amendments (CLIA) mandate that labs performing anaerobic cultures be certified at the high-complexity level. Any claim for 87075 billed from a non-CLIA-certified location will be denied, and fraudulent billing in this context carries compliance risk beyond the denied claim.

Conclusion

Anaerobic culture billing fails most often not because the test was wrong but because the documentation did not catch up to the charge: Missing specimen source, a non-covered ICD-10 diagnosis, or a requisition that said “culture” without specifying anaerobic. Fixing those three fields upstream, at the point of order entry, eliminates the majority of denials before they happen.

Pabau’s claims management workflow links ordering provider, ICD-10 diagnosis, and specimen details to the lab charge at the point of order, then routes the 837P claim through the Claim.MD clearinghouse integration with real-time eligibility checks before adjudication. To see how it works for high-volume lab billing, book a demo.

Continue your research

Need a framework for reducing lab claim denials? Denial codes in medical billing explains the most common CARC codes and how to map them to root causes in your documentation workflow.

Submitting claims through a clearinghouse? Claim.MD clearinghouse guide covers how the Pabau and Claim.MD integration handles 837P submission, real-time eligibility, and ERA remittances.

Billing multiple lab codes from the same specimen? 837 file format guide explains how to structure multi-code lab claims correctly so NCCI edits don’t bundle charges that should be separate.

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