CPT® Code 87070

Quick Reference

• Code definition: CPT 87070 covers aerobic bacterial culture of any specimen except urine, blood, or stool, including isolation and presumptive identification of recovered organisms.
• Key billing rule: MUE = 3 [3]; each unit requires a distinct anatomical source. Multiple units for the same site on the same date are not separately billable.
• Modifier essentials: Modifier 59 when pairing with 87075 (anaerobic culture) on the same specimen or billing multiple units for distinct sources; Modifier 91 for clinically indicated repeat cultures from the same source on the same date.
• Documentation must-have: The requisition must clearly identify the specimen source. Source drives CPT code selection, and an unlabeled or vaguely described specimen is the leading cause of incorrect code assignment and denial.
• Top confusion point: Billing 87070 for urine, blood, or stool is the most common miscoding. Each of those sources has its own required code: 87086 (urine), 87040 (blood), 87045 (stool).
• CLIA alert: 87070 is NOT CLIA waived [5]. The performing laboratory must hold a Certificate of High Complexity. Billing from a waiver-only lab is fraudulent.
• Payer alert: 87070 is excluded from the Medicare Physician Fee Schedule; payment is under the Clinical Laboratory Fee Schedule (CLFS) [2]. In the hospital outpatient setting, it may be conditionally packaged into a comprehensive APC.

When to Use This Code

CPT 87070 is the catch-all aerobic bacterial culture code for any specimen source outside the three anatomically excluded categories: urine, blood, and stool. In practice, it covers the majority of routine culture work in clinical microbiology labs.

Specimen types this code covers:

• Wound, abscess swab, or deep tissue aspirate (skin and soft tissue infections, surgical site infections, diabetic foot ulcers, pressure injuries)
• Respiratory specimens: sputum, bronchial wash, bronchoalveolar lavage (BAL), tracheal aspirate
• Throat and nasopharyngeal swabs
• Ear specimens: external auditory canal swabs, middle ear aspirates via tympanocentesis
• Ocular specimens: conjunctival swabs, corneal scrapings, vitreous humor
• Genital tract specimens: cervical, vaginal, urethral, or prostatic secretions when the appropriate collection is not a voided urine
• Tissue biopsy: bone (osteomyelitis workup), deep wound, intra-abdominal
• Sterile body fluid aspirates: joint fluid (septic arthritis), pleural fluid, peritoneal fluid
• Cerebrospinal fluid (CSF): verify MAC LCD; some jurisdictions have specific guidance on CSF culture coding

Scope requirements: The descriptor specifies "with isolation and presumptive identification of isolates." Both elements must be performed. If the lab only screens for the presence or absence of growth without attempting identification, use 87081 (screening only). Upcoding a screen to a full culture is an audit risk.

Setting context: 87070 is reportable by hospital outpatient labs, reference labs, and physician office labs (POLs) that hold the appropriate CLIA certificate of high complexity. PC/TC indicator 9 means the professional/technical component split does not apply; this is a laboratory-only code.

Code Differentiation Table

The single most critical differentiator is specimen source. CPT codes 87040, 87045, and 87086 are source-specific exclusions built directly into the 87070 descriptor. When you see "urine," "blood," or "stool" on the requisition, redirect to the source-specific code before assigning 87070.

flowchart TD
    A[Aerobic bacterial culture ordered] --> B{Specimen source?}
    B --> C[Blood] --> D[87040]
    B --> E[Urine] --> F[87086]
    B --> G[Stool] --> H[87045 / 87046]
    B --> I[Any other source] --> J[87070]
    J --> K{Isolation and presumptive ID performed?}
    K --> L[Yes] --> M[Report 87070]
    K --> N[Screen only] --> O[Report 87081 instead]

Billing & Modifier Rules

Modifier 59 (Distinct Procedural Service)

Use Modifier 59 in two scenarios. First, when pairing 87070 with 87075 for both aerobic and anaerobic cultures on the same specimen; CMS NCCI does not bundle these, but Modifier 59 on 87075 documents the procedures are distinct [3]. Second, when billing multiple units of 87070 on the same date for genuinely different anatomical sources (e.g., wound culture left arm and sputum culture). Append Modifier 59 to the second unit if your payer requires it.

Modifier 91 (Repeat Clinical Diagnostic Lab Test)

Modifier 91 applies when the same culture is ordered again on the same date for a clinically independent medical reason, such as serial wound monitoring in an ICU patient. Do not use Modifier 91 to resubmit after a specimen labeling error, equipment failure, or to confirm an initial result; those scenarios are not separately billable.

Units and MUE

The MUE for 87070 is 3, meaning Medicare allows up to 3 units per date of service [3]. Each unit must correspond to a distinct anatomical source with its own physician order and specimen. Three sputum cultures from the same patient on the same day, absent Modifier 91 documentation, are not separately billable as three units.

Add-on codes

• 87077 (additional methods for definitive aerobic ID): Report in addition to 87070 when presumptive identification is insufficient and additional methods are required to definitively identify an isolate (MALDI-TOF, extended biochemical panel, molecular sequencing). Bill once per isolate requiring additional ID. MUE = 4. Note that 87077 is CLIA waived, unlike 87070.
• 87184 (disk susceptibility, per plate): Report separately when susceptibility testing is performed on an isolated organism. Medical necessity requires a positive culture result.
• 87186 (MIC susceptibility, per plate): Same requirement as 87184; for MIC or breakpoint panels (Vitek, Sensititre). MUE = 12.

Neither susceptibility code is bundled with 87070 by NCCI, but billing susceptibility codes when the culture result is negative will not meet medical necessity criteria and will result in denial or overpayment recoupment.

Documentation Essentials

Required elements:

• Physician order with explicit specimen source. "Wound culture, right heel" is sufficient; "routine culture" or an unlabeled specimen is not. The source field on the requisition determines which CPT code is assignable.
• Clinical indication. Signs and symptoms supporting medical necessity (wound erythema, purulence, fever, productive cough, joint effusion) must be documented. A culture ordered without documented clinical indication for infection is at risk for medical necessity denial.
• Specimen collection details. Site, collection method (swab, aspirate, biopsy), date, and time. For wound cultures, documentation of deep tissue or abscess aspirate collection is clinically preferred over surface swab; IDSA guidelines support deep collection for diabetic foot infections [6].
• Lab report confirming the procedure elements. The report must document organism isolated and presumptive identification performed, linked to the ordering provider and patient.

Audit red flags:

• Requisitions listing "wound" without anatomical specificity on claims billing multiple units of 87070; auditors cannot verify each unit represents a distinct site without that specificity.
• Susceptibility codes billed on the same date as a 87070 that resulted in no growth; the lab report must confirm a positive culture before susceptibility testing is billable.
• 87070 billed from a POL holding only a CLIA Certificate of Waiver; high-complexity testing from a waiver-only lab triggers Medicare overpayment and False Claims Act exposure [10].
• Multiple units of 87070 billed on consecutive days for a chronic wound without documentation of clinical change justifying re-culture.

Medicare, Commercial & Medicaid Payer Rules

Medicare

87070 carries Status Code "Statutory Exclusion (from MPFS)" [2]. CMS excludes this code from Physician Fee Schedule payment and reimburses it under the Clinical Laboratory Fee Schedule (CLFS) per Section 1833(h) of the Social Security Act. CLFS rates are updated annually; since 2018, CMS has phased in market-based CLFS rates under PAMA (Protecting Access to Medicare Act), with rate reductions progressively affecting laboratory code payments [7]. Verify the current 2026 rate in the CMS CLFS lookup tool; specific payment amounts require live verification.

There is no National Coverage Determination (NCD) for 87070 [4]. Coverage is governed by MAC Local Coverage Determinations (LCDs). Coders must verify the applicable LCD for their jurisdiction, particularly for higher-volume settings like reference labs or hospital outpatient. Some MAC LCDs impose additional documentation requirements or diagnosis-level restrictions.

In the hospital outpatient setting (OPPS), the APC status indicator is "Conditionally packaged laboratory tests." When 87070 is performed on the same date as a significant covered procedure, it may be packaged into that procedure's APC payment rather than paid separately. It is paid as a standalone line item when it is the only OPPS service on the claim.

The performing laboratory must hold a CLIA Certificate of High Complexity or CMS-approved accreditation (CAP, Joint Commission, AAAHC) per 42 CFR Part 493 [10]. 87070 is not CLIA waived. MUE = 3 [3].

Commercial Payers

Commercial payer policies generally follow AMA CPT source-based code assignment logic. Prior authorization is generally not required for routine bacterial cultures, but some plans impose diagnosis-driven restrictions on high-frequency settings (e.g., repeated wound cultures for chronic wounds in skilled nursing facilities). Some commercial payers automatically downcode 87070 to 87081 for specific order types or requisition formats that do not document isolation and ID requirements; verify payer-specific order capture requirements with your contracting team.

Medicaid

State Medicaid programs generally cover 87070 when ordered by an enrolled provider with documented medical necessity. Managed Medicaid plans may impose prior authorization or frequency limits not present in fee-for-service Medicare. No specific state LCD data was identified in the research for this code; verify state-specific requirements directly.

Common Denials & Prevention

Wrong specimen source code The lab receives a requisition without a clear specimen source, or the biller defaults to 87070 without verifying the source against blood, urine, and stool exclusions. Build a front-end edit in your LIS or billing system that flags any 87070 claim where the specimen source field contains "blood," "urine," "stool," or equivalent terms, triggering redirect to 87040, 87086, or 87045.

Upcoding from screen to full culture The lab performed a rapid screen for pathogen presence without completing isolation and presumptive identification, but 87070 was billed. Ensure the LIS work order and final report document that isolation and presumptive ID were performed. If the procedure stopped at screening, bill 87081. The difference is substantive, not semantic.

Multiple units for same source without Modifier 91 Concurrent or sequential cultures from the same wound site are billed as multiple units of 87070 without documentation of clinical distinctiveness. Require the ordering provider to document the specific medical reason for repeat cultures from the same site on the same date, then attach Modifier 91 and include the clinical indication on the claim.

Susceptibility codes billed without positive culture Batch billing of 87184 or 87186 alongside 87070 without confirming culture positivity before claim submission. Implement a billing edit requiring positive culture documentation before susceptibility codes release to claim; the lab report result and organism identification must precede susceptibility billing.

CLIA certificate mismatch A POL holds a Certificate of Waiver or Registration only but bills 87070 as part of an in-office diagnostic workup. Audit CLIA certificate levels for every POL billing 87070. Retroactive denials from CLIA certificate mismatches carry False Claims Act exposure [10]. OIG has historically focused work plan attention on this category of laboratory billing [8].

Coding Scenarios

Scenario 1: Infected diabetic foot ulcer, aerobic culture only

A wound care physician debrides a diabetic patient's right heel ulcer with signs of infection (erythema, purulent discharge). A deep tissue specimen is collected via curette and submitted for aerobic bacterial culture. The lab isolates Staphylococcus aureus; presumptive ID is made by colonial morphology and catalase/coagulase testing. Susceptibility testing is not ordered.

Correct coding: 87070 x 1 unit

Why: The specimen is a wound, not blood, urine, or stool. Isolation and presumptive ID were performed, satisfying the full 87070 descriptor. No susceptibility testing was ordered, so 87184/87186 are not reportable. IDSA SSTI guidelines support deep tissue culture for purulent skin and soft tissue infections [6].

Scenario 2: Wound specimen with aerobic, anaerobic, and susceptibility testing

A surgeon orders both aerobic and anaerobic cultures on a deep abdominal wound. The aerobic culture yields Pseudomonas aeruginosa; susceptibility testing is performed by MIC panel. The anaerobic culture grows Bacteroides fragilis (presumptive ID only).

Correct coding: 87070, 87075-59, 87186

Why: 87070 for aerobic; 87075 with Modifier 59 for the distinct anaerobic procedure on the same specimen [3]. 87186 for MIC susceptibility of the aerobic isolate. If the Bacteroides required additional methods beyond presumptive ID, add 87076 for the anaerobic isolate.

Scenario 3: ICU patient with distinct specimen sources, same day

An ICU patient with ventilator-associated pneumonia and a concurrent surgical site infection has both a sputum culture and a chest wound culture ordered the same morning. Each is a separate aerobic bacterial culture. Sputum yields Klebsiella pneumoniae; wound yields Enterococcus faecalis. Disk susceptibility is ordered on both isolates.

Correct coding: 87070 x 2 units (Modifier 59 on second unit per payer requirement), 87184 x 2

Why: Two genuinely distinct anatomical sources (respiratory specimen and wound) justify 2 units of 87070; the MUE of 3 accommodates this [3]. Each positive culture supports its own susceptibility billing.

Scenario 4: Throat culture with isolate requiring definitive identification

A patient with exudative pharyngitis has a negative rapid strep antigen. The physician orders a routine throat culture. The aerobic culture grows a slow-fermenting gram-negative rod requiring MALDI-TOF mass spectrometry for definitive species identification beyond presumptive methods.

Correct coding: 87070, 87077

Why: Throat swab is "any other source," making 87070 correct. The isolate required additional methods beyond presumptive ID; that is the specific indication for 87077 per isolate. The rapid strep antigen test (87430 or 87650/87651) is separately reportable if performed on the same day, as those are antigen detection procedures, not cultures.

Related Codes

• 87040: Bacterial culture, blood, aerobic. Required when specimen is blood; do not use 87070.
• 87045: Bacterial culture, stool, aerobic (Salmonella/Shigella). Required when specimen is stool; do not use 87070.
• 87046: Bacterial culture, stool, additional pathogens, each plate. Add-on to 87045 for expanded stool pathogen panels.
• 87075: Bacterial culture, any source except blood, anaerobic. Companion code for anaerobic culture of the same 87070 specimen.
• 87076: Anaerobic isolate, additional definitive ID methods, each isolate. Add-on to 87075 when definitive anaerobic ID requires supplemental methods.
• 87077: Aerobic isolate, additional definitive ID methods, each isolate. Add-on to 87070 when presumptive ID is insufficient.
• 87081: Culture, presumptive, pathogenic organisms, screening only. Lower-level alternative when isolation and identification are not performed.
• 87086: Bacterial culture, urine, quantitative colony count. Required when specimen is urine; do not use 87070.
• 87184: Susceptibility, disk method, per plate. Separately reportable after positive 87070; Kirby-Bauer disk diffusion.
• 87186: Susceptibility, microdilution or agar dilution (MIC), per plate. Separately reportable after positive 87070; MIC automated panels.

Sources

1. CPT 87070 Official Descriptor, verified via Coding Ahead CPT database: "Culture, bacterial; any other source except urine, blood or stool, aerobic, with isolation and presumptive identification of isolates." AMA.
2. CMS Clinical Laboratory Fee Schedule — CMS — Payment methodology for 87070 (Statutory Exclusion from MPFS; paid under CLFS).
3. CMS NCCI Policy Manual and MUE Tables — CMS — MUE = 3 for 87070 (database verified); quarterly PTP edit pair tables.
4. CMS Medicare Coverage Database — CMS — No NCD for 87070; MAC LCDs govern coverage by jurisdiction.
5. CDC CLIA Program: Test Complexity — CDC — Aerobic bacterial culture classified as HIGH complexity; 87070 not CLIA waived (database verified).
6. IDSA Practice Guideline: Skin and Soft Tissue Infections (2014) — IDSA — Recommends culture and susceptibility for purulent SSTIs; deep tissue collection preferred for diabetic foot infections.
7. Federal Register: CMS MPFS and CLFS Final Rules — Federal Register — Annual CLFS rate updates under PAMA; MPFS final rules affecting lab payment methodology.
8. HHS OIG Work Plan: Laboratory Services — HHS OIG — Ongoing audit focus on laboratory upcoding, unbundling, and invalid physician orders.
9. PAMA (Protecting Access to Medicare Act) CLFS market-based rate phase-in, 2018 onward. Federal Register annual final rules.
10. 42 CFR Part 493: Laboratory Requirements — eCFR — CLIA certificate of high complexity required for 87070; billing from waiver-only labs constitutes fraud.