ERA (Endometrial Receptivity Array) Billing: CPT Codes and Coverage

The Endometrial Receptivity Array (ERA) — marketed by IGENOMIX as the Endometrial Receptivity Analysis — is a transcriptomic test that evaluates gene expression in endometrial tissue to identify each patient's personalized window of implantation (WOI). In clinical practice, ERA is most commonly ordered for patients with recurrent implantation failure (RIF) following multiple failed embryo transfer cycles with good-quality embryos. For fertility billing staff, ERA creates a distinct set of challenges that routine IVF or FET cycle billing does not: two separate billable charge streams from different entities, inconsistent payer coverage that varies at the plan level rather than the carrier level, a proprietary laboratory PLA code that some clearinghouses and payer fee schedules do not recognize, and documentation requirements that differ sharply between payers that cover the test and those that classify it as investigational. This guide addresses every billing layer in the ERA encounter, from pre-service verification through denial management and downstream FET billing.

The Two-Charge Structure of Every ERA Encounter

Every ERA clinical encounter generates two distinct billable components that are typically submitted by different entities, on different timelines, under different NPI and CLIA numbers. Fertility billing staff need to understand both charge streams even if the practice only directly bills for one of them.

• The endometrial biopsy (office procedure): Performed by the fertility physician in the office using a Pipelle, Novak curette, or similar sampling instrument. Billed on a CMS-1500 under the fertility practice's billing NPI and tax ID. This is the component the fertility practice owns and controls.
• The ERA test (molecular laboratory analysis): Performed by IGENOMIX at its reference laboratory. IGENOMIX bills patients or their insurance payers directly under its own NPI and CLIA number. The fertility practice typically does not bill for this component unless the practice has a specific arrangement with the lab that differs from the standard IGENOMIX billing model.
• Pathology review of the biopsy specimen: If the practice sends the biopsy specimen to a local pathology group for gross and microscopic review before or separately from the ERA analysis, a surgical pathology charge (CPT 88305) may be generated by the pathology group as a third billing stream. This is an independent claim from a separate billing entity.

The coordination between these billing streams is where ERA claim errors most commonly originate. When the fertility practice does not communicate the ERA order and cost structure to the patient before the biopsy appointment, IGENOMIX billing the patient directly for the ERA test at list price — which ranges from $800 to $1,400 — creates complaints that come back to the fertility practice. The billing and patient services team should have a standard ERA financial counseling protocol that explains both expected bills before the biopsy is scheduled.

CPT Codes for ERA Billing

Endometrial Biopsy Procedure Codes

The endometrial biopsy required to obtain the ERA specimen is billed using CPT 58100 in the vast majority of clinical encounters. If cervical dilation was required to obtain the specimen — uncommon for ERA but clinically necessary in some nulliparous patients or those with cervical stenosis — CPT 58120 applies instead. The procedure note must document the biopsy method used, whether dilation was performed or attempted, the clinical indication for the procedure, and that the specimen was submitted for ERA analysis. For patients who also undergo a mock transfer on the same date of service, both 58340 (catheterization and introduction for saline infusion sonohysterography or mock transfer) and 58100 may be billed on the same date with modifier 59 on the second procedure to indicate distinct services.

ERA Laboratory Test Code

The ERA test is a proprietary transcriptomic analysis of 248 genes associated with endometrial receptivity, performed on RNA extracted from the endometrial biopsy specimen. The American Medical Association assigned IGENOMIX a Proprietary Laboratory Analyses (PLA) code specific to this test: CPT 0233U. This PLA code should be used for the IGENOMIX ERA product instead of unlisted codes 81479 (unlisted molecular pathology procedure) or 81599 (unlisted multianalyte assay with algorithmic analysis). Older charge templates at some fertility practices still list 81479 for ERA — this creates adjudication uncertainty because payer systems process unlisted codes with manual review, while PLA codes have a direct descriptor that maps to IGENOMIX's negotiated rate where applicable. Practices or labs submitting ERA claims should verify whether the target payer has loaded 0233U into its fee schedule; some payers that cover ERA have not yet updated their system to recognize the PLA code and require a workaround submission with 81479 plus an ERA-specific narrative.

ICD-10 Diagnosis Code Selection for ERA

Selecting the correct ICD-10 code for the ERA biopsy encounter determines which benefit tier adjudicates the claim, which medical necessity criteria apply, and whether the claim routes to a fertility exclusion or a diagnostic infertility coverage bucket. The wrong primary diagnosis on an ERA biopsy claim can produce a denial that is difficult to appeal because the code selection itself was the error. The following codes apply to ERA billing:

ERA Coverage Across Payer Types in 2026

ERA coverage is inconsistent across payer types, varies at the individual plan level rather than the carrier level, and changes as clinical evidence accumulates. Benefits verification for ERA must be performed at the specific plan level for each patient. Assuming coverage based on carrier name alone is a systematic billing error.

Commercial Major Medical Plans

Most commercial major medical plans from Aetna, Cigna, UnitedHealthcare, Humana, and national BCBS plans classify ERA testing as investigational or experimental and do not cover it under either the medical or fertility benefit. Aetna's clinical policy bulletin on genetic and molecular testing explicitly categorizes endometrial receptivity testing as investigational for all indications, citing insufficient evidence that personalized WOI timing improves live birth outcomes compared to standard luteal phase support protocols. Cigna and UHC maintain similar non-coverage positions in their coverage policies. State Blue Cross Blue Shield plans vary more widely — some BCBS plans with mandatory fertility benefit compliance have incorporated ERA into their covered services for patients with documented recurrent implantation failure after three or more blastocyst-stage transfers.

For major medical commercial plans that exclude ERA as investigational, there is no productive path through a prior authorization request — the denial will be on policy grounds, not clinical grounds, and appeals on medical necessity will not succeed. When benefits verification confirms ERA is non-covered as investigational, move directly to patient financial responsibility documentation and do not submit a claim for the ERA test to the payer. Submitting non-covered claims generates EOBs that confuse patients about their financial responsibility, creates false AR on the practice books, and can constitute a compliance issue if the practice subsequently balance-bills the patient after receiving an EOB.

Fertility Benefit Managers

• Progyny: ERA may be covered within a Progyny Smart Cycle if specifically authorized as part of the pre-cycle workup. Progyny applies its own medical necessity criteria for ERA approval, which generally require documentation of at least two prior failed transfers with good-quality blastocysts (euploid if PGT-A was performed). ERA authorization through Progyny is separate from the cycle authorization itself — it must be requested explicitly, not assumed as part of a general FET authorization. If ERA is approved, both the biopsy charge (58100) and the IGENOMIX ERA test fee may be credited against the authorized Smart Cycle value depending on the employer's benefit structure.
• WINFertility: ERA coverage under WINFertility-administered plans is employer-specific and must be verified for every individual patient. Some WINFertility employer clients have added ERA to their fertility benefit schedule; others exclude it as investigational. WINFertility's benefits verification call will specify ERA coverage by plan. Do not infer ERA coverage from IVF or FET coverage under the same WINFertility plan — ERA is evaluated independently under the plan document.
• Carrot Fertility: Carrot uses a direct-to-employee reimbursement model. The fertility practice bills the patient directly for the endometrial biopsy at cash-pay rates. The patient submits IGENOMIX receipts for ERA test reimbursement to Carrot up to their available balance. There is no payer-to-clinic claim submission pathway for ERA under Carrot. Ensure front desk staff understand this at check-in so Carrot patients are not asked for insurance information for the ERA appointment.
• Maven Clinic, Ovia Health, and newer platforms: Each platform has its own claims submission pathway. When the practice encounters a newer fertility benefit manager for the first time, contact the platform's provider services line before the ERA appointment to confirm how the biopsy claim should be submitted and whether the ERA lab fee runs through the platform or directly to the patient.

State Mandate Plans

Fertility insurance mandates in most states — Illinois, New York, New Jersey, California (SB-729), Connecticut, Massachusetts, Maryland, and others — require coverage of infertility diagnosis and treatment but generally do not enumerate ERA testing as a specifically required covered service. However, some mandate-compliant plans have begun including ERA in their covered fertility diagnostic services, particularly in states with comprehensive mandates. The question to ask during benefits verification is specific: "Does this plan cover ERA testing (CPT 0233U) for recurrent implantation failure, and if so, what is the prior authorization process?" Do not assume ERA is covered because the plan covers IVF cycles under a state mandate.

Prior Authorization for ERA: What to Request and When

Authorization for ERA splits across the two billable components and must be pursued independently for each. The practice's authorization team should treat ERA biopsy authorization and ERA test authorization as separate work items.

• Authorization for CPT 58100 (endometrial biopsy): Many payers require prior authorization for endometrial biopsy when the procedure is performed by a fertility specialist or when the claim carries an infertility diagnosis code. Even when the ERA test itself is non-covered as investigational, the biopsy procedure may process under the medical benefit as a gynecologic procedure with its own authorization requirement. Verify biopsy authorization requirements separately from ERA test coverage — these are different benefit tiers with different authorization workflows.
• Authorization for CPT 0233U (ERA test): If the payer covers ERA at all, prior authorization is required in virtually every case. The authorization request must include: (1) the patient's diagnosis with ICD-10 coding, (2) documentation of the number of prior failed transfers with embryo quality information, (3) a physician letter of medical necessity documenting the clinical rationale for personalized WOI evaluation, and (4) the IGENOMIX test requisition form identifying the specific panels ordered (ERA alone vs. ERA + EMMA + ALICE). Providing incomplete documentation is the primary reason ERA authorization requests are initially denied when the payer does cover the test.
• Self-funded plan exceptions: Self-funded employer plans administered under ERISA can override the carrier's standard coverage policy on ERA. An employer plan administered by Aetna may cover ERA even though Aetna's national medical policy excludes it. When the employer's Summary Plan Description (SPD) or benefits portal indicates potential ERA coverage, request authorization regardless of what the carrier's standard policy states. The SPD governs, not the carrier's clinical policy bulletin, for self-funded plans.
• When ERA is non-covered: When benefits verification confirms ERA is excluded as investigational, do not submit a prior authorization request. Instead, document the non-coverage determination in the patient's billing record and proceed to financial responsibility documentation before the biopsy appointment.

Common ERA Billing Denials and Prevention

ERA billing denials concentrate in predictable patterns. Each denial type has a distinct root cause and a specific prevention strategy at the front end of the billing workflow.

• Denial: ERA classified as investigational or experimental. Root cause: the plan excludes ERA under its investigational services policy and this was not identified at benefits verification. Prevention: always run an ERA-specific benefits verification question — "Is CPT 0233U covered under this plan?" — before the biopsy appointment, not after. If non-covered, collect patient financial responsibility documentation and do not submit the claim. On a received denial for investigational classification, do not appeal on clinical grounds alone unless the plan is self-funded and the SPD does not exclude ERA; the payer's policy position will not change based on a clinical letter absent a coverage carve-out in the plan document.
• Denial: 58100 denied under fertility exclusion. Root cause: the biopsy was billed with Z31.83 as primary, routing the claim to the fertility benefit adjudication unit, which denied under a fertility exclusion. Prevention: for patients whose plans exclude fertility benefits, bill the ERA biopsy with Z31.41 (encounter for fertility testing) or N98.89 (complications associated with artificial fertilization) as primary. Appeal any 58100 denials based on fertility exclusion by arguing that endometrial biopsy is a diagnostic office procedure and a standard gynecologic service not limited to fertility patients.
• Denial: CPT 0233U not recognized or priced at $0. Root cause: the payer has not loaded 0233U into its fee schedule and auto-denies or reprices the claim. Prevention: before the first ERA submission to any payer, call provider services and ask whether 0233U is on their fee schedule. If not, ask which CPT code the payer will accept for ERA testing. Some payers require 81479 with a narrative attachment; others require a call to set up a single-case agreement.
• Denial: 58100 denied as duplicate of a recent endometrial biopsy claim. Root cause: the patient had a prior biopsy claim (from a mock transfer workup or prior FET cycle) recently on file, and the payer's duplicate claim edit flagged the ERA biopsy. Prevention: append modifier 59 to 58100 and include a brief narrative note that this biopsy was performed for ERA testing at a distinct point in the treatment cycle, with a separate clinical purpose from any prior biopsy on file.
• Denial: ERA authorization expired before biopsy was performed. Root cause: cycle delays or patient rescheduling pushed the ERA biopsy outside the authorization window. Prevention: track ERA biopsy authorizations with the same expiration-date follow-up workflow used for IVF authorizations. ERA biopsies are often performed in a mock/prep cycle before the actual FET cycle, meaning the authorization may need to span two calendar months. Confirm the authorization expiration date at approval and flag it in the scheduling system with a warning if the biopsy is scheduled close to the expiration window.

Documentation Requirements for ERA Claims

ERA claim documentation requirements parallel other diagnostic procedures, with specific additions driven by the recurrent implantation failure indication that must appear in both the chart and the claim. The following elements are required for a defensible ERA claim package:

• Physician order for ERA testing with clinical indication: The order must document why ERA was ordered with enough specificity to support medical necessity — "ERA testing for personalized window of implantation assessment in patient with recurrent implantation failure after three failed euploid blastocyst transfers" is defensible. Vague orders such as "ERA per patient request" create audit exposure for any claim that goes to payer review.
• Pre-procedure office visit note: The visit note in which ERA was discussed and ordered must document the patient's complete IVF/FET history, number and dates of prior transfers, embryo quality and ploidy status at each transfer, transfer outcomes including beta-hCG results, and the physician's clinical reasoning for ordering ERA at this point in the care plan. This is the primary document payers request during medical necessity review.
• Procedure note for 58100: The biopsy procedure note must document the method used, whether a tenaculum or local anesthesia was employed, any difficulty accessing the endometrial cavity, specimen appearance, and that the specimen was submitted to IGENOMIX for ERA analysis. For ERA-specific biopsies, include notation that the clinical purpose is WOI assessment, not routine pathology.
• IGENOMIX test requisition: The signed laboratory requisition from IGENOMIX identifies the specific panel ordered (ERA alone vs. ERA + EMMA + ALICE combined). This document is essential if the payer requests supporting documentation for the 0233U claim.
• ERA result report: The final ERA result report from IGENOMIX (pre-receptive, receptive, or post-receptive classification with recommended embryo transfer timing) should be in the patient's chart within 21 days of the biopsy. If the ERA result directed a change in the subsequent FET protocol, the FET pre-procedure visit note should reference the ERA result and the adjusted transfer timing. This closes the clinical loop and establishes that ERA provided a result that meaningfully directed care.
• Patient financial responsibility documentation: For non-covered ERA tests, a signed financial agreement documenting that the patient understood their financial responsibility before the procedure was performed. For Medicare-eligible patients (who should not be receiving fertility services under Medicare, but who may have Medicare as a secondary payer on a commercial fertility plan), a standard Medicare ABN may be required to establish patient liability for the non-covered service.

ERA vs. Mock Transfer: Avoiding Charge Capture Confusion

ERA biopsies are sometimes confused with mock transfer procedures in charge capture because both occur during a pre-FET preparatory cycle and both involve a uterine intervention. They are clinically and billably distinct procedures. A mock transfer — or trial transfer — evaluates uterine cavity access, cervical canal anatomy, and the optimal catheter path for embryo transfer. Depending on exactly what was performed, it may be billed using CPT 58340 (catheterization and introduction for saline infusion sonohysterography or mock transfer), an appropriate E&M code with in-office procedure documentation, or another code depending on the procedure performed and payer contract.

An ERA biopsy is a tissue-sampling procedure billed as CPT 58100, resulting in a specimen sent to the laboratory. Some patients undergo both a mock transfer and an ERA biopsy on the same date of service. When both are performed on the same date, bill both applicable codes with modifier 59 on the second procedure to indicate distinct, separately documented services. Maintain separate procedure notes for each. Bundling errors — submitting only one code when two procedures were performed, or using 58340 for the ERA biopsy — are among the most frequent ERA charge capture failures and typically result in under-billing rather than denial.

Downstream Billing After ERA Results

The ERA result affects the documentation and billing for the subsequent FET cycle. When ERA identifies a non-receptive window and the FET protocol is modified — typically by extending progesterone supplementation by 12 to 24 hours before transfer — the physician's FET pre-procedure visit note must explicitly reference the ERA result and document the clinical decision to adjust the transfer schedule. This documentation supports medical necessity for any monitoring visits or laboratory services performed outside the standard FET protocol timeline. Without this reference in the FET note, the connection between the ERA result and the modified cycle protocol is missing from the chart, and any payer review of the FET claim will find a non-standard protocol with no documented rationale.

Practices that perform a repeat ERA biopsy after a non-receptive result — which IGENOMIX recommends for pre-receptive results to confirm the revised WOI before transfer — should ensure the repeat biopsy has its own procedure note, IGENOMIX requisition, and authorization (if applicable). A repeat ERA claim submitted without documentation that the initial ERA result was non-receptive, or without a new IGENOMIX requisition tied to the repeat sample, will appear to be a duplicate claim in the payer system and will be denied on that basis. The repeat biopsy claim should include a reference in the clinical notes and claim narrative to the initial ERA result date and the basis for the repeat testing.

Building an ERA Billing Workflow

ERA billing errors cluster at three stages of the revenue cycle: pre-service (coverage not verified or financial responsibility not collected), charge capture (wrong code used, modifier missing, mock transfer and ERA conflated), and post-service (repeat biopsy submitted as duplicate, FET documentation missing ERA reference). A structured workflow that addresses each stage prevents the most common claim failures:

• Pre-service benefits verification script: For every ERA patient, run a verification that asks the payer explicitly: (1) Is CPT 0233U covered under this specific plan? (2) Is CPT 58100 covered for an endometrial biopsy by a fertility specialist in an office setting? (3) Is prior authorization required for either? (4) What medical necessity criteria must be documented for ERA authorization? Document the answers with the representative name, date, and reference number in the patient's billing record.
• Pre-appointment financial counseling: Before the ERA biopsy appointment, the billing or patient services team must walk the patient through both expected bills — the practice's 58100 charge and the IGENOMIX ERA test fee. If ERA is non-covered, collect the signed financial responsibility agreement at this stage. Do not defer financial counseling to check-in on the day of the biopsy.
• ERA-specific charge template: Create a dedicated charge template for ERA biopsy encounters that defaults to CPT 58100 (not 58340 or 58120), includes ERA-appropriate ICD-10 code options, and requires a mandatory field confirming that the IGENOMIX requisition was submitted. This prevents the use of a mock transfer template or a generic gynecology biopsy template that may populate incorrect defaults.
• Post-result documentation follow-up: When the ERA result returns (typically within 14 to 21 days), ensure the treating physician completes a result review note that documents the ERA classification and any modification to the planned FET protocol. This note protects the downstream FET claim and establishes that ERA provided a result that directed clinical care.
• Denial tracking by ERA-specific category: Track ERA-related denials separately from general IVF and FET denials. ERA denials follow a distinct pattern — investigational classification, fertility benefit routing, PLA code non-recognition, duplicate claim flags — that differs from standard cycle billing denials. Separate tracking lets the billing team identify systemic payer issues and address them before they accumulate.