CPT 88350Laboratory

Imfluor ea addl 1antb stn px

CPT 88350 is a laboratory test code for adding extra antibody staining to tissue samples using immunofluorescence microscopy. It's used when pathologists need to identify additional proteins or markers beyond the first antibody stain to diagnose diseases like autoimmune disorders or cancers.

Showing rates for

National Average

Base Medicare rate

$107.07

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

0.59

PE RVU (NF)

2.7

MP RVU

0.02

Total RVU

3.31

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

NCCI bundling edits

Loading bundling edits…

Billing tips

Bill 88350 per additional antibody, not per slide or specimen. If testing uses 5 different antibodies, report the primary code once plus 88350 x 4 units.
Impact: Proper unit reporting can increase reimbursement by $321.21 (3 additional antibodies) compared to incorrectly billing only the primary code
Always link to the primary immunofluorescence code (88346 for direct method or 88347 for indirect method). CPT 88350 cannot be billed without a primary IF code on the same date.
Impact: Prevents automatic denials; 88350 alone will reject 100% of the time as an add-on code requiring a base procedure
Document each specific antibody used by name (e.g., anti-IgG, anti-C3, anti-fibrinogen) in the pathology report. Generic terms like 'multiple antibodies' insufficient for audit defense.
Impact: Detailed antibody documentation reduces denial rate by approximately 35% during post-payment audits and supports medical necessity
For kidney biopsies with standard IF panels (typically 4-6 antibodies), ensure all additional antibodies beyond the first are captured. Many practices undercode by 2-3 units per case.
Impact: Complete coding of a 6-antibody panel yields $535.35 additional revenue (5 x $107.07) compared to billing only the primary code
Verify payer-specific policies on maximum units per day. Some Medicare MACs limit to 4-5 additional antibodies without additional documentation; commercial payers vary widely.
Impact: Pre-authorization for panels exceeding 4 antibodies can prevent denials of $107.07 per antibody above payer threshold
When billing split components (26/TC), ensure both facility and provider use matching dates of service and specimen identifiers to prevent coordination of benefits issues.

Live Field Datano reports yet

Real billers contribute denial patterns and appeal strategies for this code. Once 5+ reports come in, you’ll see live aggregated data here — the only place this exists, free.

Working with CPT 88350?

Get the free Revenue Protection Toolkit — the denial triggers, modifier pitfalls, and bundling conflicts that quietly cost you reimbursement. Instant download.

Help build the field knowledge

MedPayIQ gets smarter as billers contribute. If you've had this code denied, share what happened so others learn from it. Anonymous, no patient info.

Related actions

Frequently asked questions

What is the Medicare reimbursement rate for CPT code 88350 in 2025?

The 2025 Medicare national average reimbursement for CPT 88350 is $107.07 for both facility and non-facility settings. This rate is based on 3.31 total RVUs (0.59 work RVU + 2.7 practice expense RVU + 0.02 malpractice RVU) multiplied by the 2025 conversion factor of $32.3465. Actual payment may vary by geographic locality based on GPCI adjustments.

How many times can you bill CPT 88350 per specimen?

CPT 88350 should be billed once for each additional antibody used beyond the first antibody (which is included in the primary immunofluorescence code 88346 or 88347). There is no absolute CMS limit, but most payers question medical necessity beyond 4-5 additional antibodies without supporting documentation. For example, a standard kidney biopsy IF panel using 6 antibodies would be coded as 88346 x 1 plus 88350 x 5.

What is the difference between CPT 88346 and 88350?

CPT 88346 is the primary code for immunofluorescence microscopy using the direct antibody method with the first single antibody stain. CPT 88350 is an add-on code reported for each additional antibody beyond the first. You must bill 88346 (or 88347 for indirect method) first, then add 88350 for each extra antibody. For example, testing with 3 antibodies requires 88346 x 1 and 88350 x 2.

Does CPT 88350 require a modifier when billing multiple units?

Modifier 59 or XU may be required when billing multiple units of 88350 to indicate each unit represents a distinct antibody stain, particularly if payer edits flag potential duplicates. Modifier 26 is used when billing only the professional component (interpretation), and TC for technical component only. Modifier 91 applies when repeat testing is medically necessary on the same day. Check individual payer policies as requirements vary.

Can CPT 88350 be billed with flow cytometry codes?

No, CPT 88350 is specific to immunofluorescence microscopy and should not be billed with flow cytometry codes (88184-88189). These are distinct methodologies: immunofluorescence uses microscopic visualization of fluorescent antibodies on tissue sections, while flow cytometry analyzes cells in suspension. Billing both for the same analysis purpose may trigger unbundling denials. Use the appropriate code family for the actual technique performed.

What documentation is needed to support billing CPT 88350?

Required documentation includes: the pathology report listing each specific antibody by name (e.g., anti-IgG, anti-C3), clinical indication for the testing, specimen type and source, pathologist interpretation of each antibody's staining pattern, and the technical method used. Generic statements like 'immunofluorescence performed' are insufficient. Each antibody billed must be individually identifiable in the record to survive audits.

Is CPT 88350 covered by Medicare for skin biopsies?

Yes, Medicare covers CPT 88350 for skin biopsies when medically necessary to diagnose conditions like pemphigus, bullous pemphigoid, lupus erythematosus, vasculitis, or dermatitis herpetiformis. The clinical indication must support the need for immunofluorescence testing. Direct immunofluorescence of skin typically uses 3-4 antibodies (IgG, IgA, IgM, C3), which would be coded as 88346 plus 88350 x 2-3, all covered when diagnosis codes support autoimmune or bullous disease evaluation.