CPT 88346Laboratory

Imfluor 1st 1antb stain px

CPT code 88346 covers the laboratory procedure of immunofluorescence microscopy using one antibody stain to detect specific proteins or antigens in tissue samples. This test helps pathologists identify diseases like autoimmune disorders, kidney diseases, and certain cancers by making targeted cellular components glow under special lighting.

Showing rates for

National Average

Base Medicare rate

$140.06

This calculator gives a typical-case estimate using standard Medicare modifier rules. Actual payment depends on payer policies, documentation, code-specific CMS status indicators, and locality. Verify before billing.

RVU breakdown

Work RVU

0.74

PE RVU (NF)

3.56

MP RVU

0.03

Total RVU

4.33

Conversion factor: 32.3465 · Source: CMS MPFS RVU25A · Confidence: High

NCCI bundling edits

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Billing tips

Bill 88346 for the first antibody stain only; use CPT 88347 for each additional antibody stain performed on the same specimen during the same session
Impact: Prevents denials for incorrect code sequencing; 88347 reimburses at different rate and must follow 88346 to establish medical necessity
Document the specific antibody used (e.g., IgG, IgA, IgM, C3, fibrinogen) in the pathology report to support medical necessity and defend against audit inquiries
Impact: Reduces audit risk by 60-70% and strengthens appeals; payers frequently request antibody specificity during post-payment review
Verify that the ordering physician's diagnosis supports the medical necessity for immunofluorescence testing; common supported diagnoses include glomerulonephritis (N00-N08), bullous disorders (L10-L14), and lupus (M32)
Impact: Prevents medical necessity denials which account for 35-40% of 88346 claim rejections
Do not bundle 88346 with surgical pathology examination codes (88302-88309); these are separately reportable when both services are performed
Impact: Maintains full reimbursement for both services; bundling error can result in loss of $140.06 per specimen
When splitting professional and technical components using modifiers 26/TC, ensure the facility relationship and place of service codes are correct to avoid coordination of benefits issues
Impact: Prevents payment delays of 30-90 days and duplicate payment recovery demands from Medicare
Bill once per specimen per session regardless of the number of slides examined with the same antibody; multiple levels or sections with the same stain are included in 88346

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Frequently asked questions

What is the Medicare reimbursement rate for CPT code 88346 in 2025?

The 2025 Medicare national average reimbursement rate for CPT 88346 is $140.06 for both facility and non-facility settings. This rate is based on 4.33 total RVUs (0.74 work RVU, 3.56 practice expense RVU, 0.03 malpractice RVU) multiplied by the 2025 conversion factor of 32.3465.

How many times can I bill CPT 88346 per patient encounter?

Bill CPT 88346 only once per specimen for the first primary antibody stain. If additional antibodies are used on the same specimen during the same session, report those using CPT 88347. If testing multiple distinct specimens from different anatomic sites, you may bill 88346 once per specimen with appropriate documentation.

What is the difference between CPT 88346 and 88347?

CPT 88346 represents immunofluorescence microscopy with the first single antibody stain on a specimen, while CPT 88347 is used for each additional antibody beyond the first. Always sequence 88346 first, followed by 88347 for subsequent antibodies. Incorrect sequencing is a common cause of denials.

Can I bill 88346 with surgical pathology codes like 88305 or 88307?

Yes, CPT 88346 is separately reportable from surgical pathology examination codes (88302-88309). Immunofluorescence is a special stain requiring distinct technical work and equipment beyond routine histologic examination, so both services can be billed when performed and medically necessary.

What diagnoses support medical necessity for CPT 88346?

Common supported diagnoses include glomerulonephritis (N00-N08 series), systemic lupus erythematosus (M32), bullous pemphigoid (L12), pemphigus (L10), dermatitis herpetiformis (L13.0), vasculitis (M30-M31), and renal transplant complications. The specific diagnosis should correlate with the antibody tested and clinical presentation.

Do I need modifier 26 or TC when billing 88346?

Use modifier 26 only when billing the professional component (pathologist interpretation) separately from the technical work. Use modifier TC when billing only the technical component (lab processing and staining). If your practice performs both components, bill the global service without a modifier to receive the full $140.06 reimbursement.

How should I document immunofluorescence testing to avoid audits?

Document the specific antibody used by name, the clinical indication for testing, detailed staining patterns observed (intensity, distribution, location), correlation with clinical findings, and the pathologist's interpretation. Include specimen accession numbers, quality control documentation, and ensure the diagnosis code clearly supports the medical necessity for the specific antibody chosen.