CPT Code 01924: Anesthesia for arterial interventional radiology

Key Takeaways

CPT Code 01924 describes anesthesia for therapeutic interventional radiological procedures involving the arterial system, not otherwise specified.

The code carries 5 base units; total reimbursement is calculated as (Base Units + Time Units) multiplied by the Medicare conversion factor, which varies by locality.

Modifiers AA, QZ, QK, QX, and QY are the most commonly applied; choosing the wrong modifier is the leading cause of claim denial for this code.

Practice management software like Pabau can keep pre-anesthesia evaluation notes, anesthesia records, and consent forms organized and attached to the patient file to support clean claims.

CPT Code 01924 reports anesthesia for a therapeutic interventional radiological procedure involving the arterial system, used when no more specific anesthesia code applies. It carries 5 base units and is billed by anesthesiologists (modifier AA) or CRNAs (QZ, QK, QX) for arterial interventions such as embolization, angioplasty, and stenting performed in an interventional radiology suite.

This reference covers the complete billing picture for CPT Code 01924: official description, 5 base units, all applicable modifiers, Medicare reimbursement rates, ICD-10 crosswalk, billing guidelines, and how it compares to adjacent radiological anesthesia codes. Revenue cycle staff, anesthesiologists, and CRNAs will find the documentation and sequencing details most useful.

CPT Code 01924: definition and clinical description

Official short description: Anesthesia for therapeutic interventional radiological procedures involving the arterial system; not otherwise specified.

CPT Code 01924 is reported when an anesthesia provider administers anesthesia during a therapeutic (not diagnostic) interventional radiology procedure that targets the arterial system. The “not otherwise specified” qualifier is critical: it means no other, more specific anesthesia code in the interventional radiology section covers the procedure being performed. According to the American Medical Association’s CPT code set, the code falls within the Anesthesia for Radiological Procedures section of the CPT codebook, which groups together codes 01916 through 01942.

Clinically, CPT Code 01924 applies to arterial interventions such as embolization, arterial stenting, angioplasty, and other therapeutic procedures performed in an interventional radiology suite where anesthesia is required and no narrower code captures the situation. The code does NOT apply to diagnostic-only imaging; the procedure must be therapeutic in nature.

CPT 01924 base units and time unit calculation

CPT Code 01924 carries a base unit value of 5. Base units represent the intrinsic complexity and risk of the anesthesia service, independent of how long the procedure takes. They are assigned by the American Society of Anesthesiologists (ASA) and incorporated into the CMS Physician Fee Schedule.

Time units are added on top of the base units. Medicare calculates one time unit for every 15 minutes of anesthesia, counting from the point of induction to emergence. For a 90-minute procedure, that is 6 time units (90 / 15 = 6).

The reimbursement formula:

This conversion factor varies by geographic locality and changes annually. The illustrative $22 figure above is for orientation purposes only. Anesthesia is not priced using RVUs or the standard Medicare Physician Fee Schedule the way most other CPT services are — reimbursement is (base units + time units) multiplied by the locality-adjusted Anesthesia Conversion Factor. Always verify both the base unit value and the current anesthesia conversion factor for your MAC locality directly from the CMS Anesthesia fee schedule or your MAC’s published rates before submitting a claim.

Applicable modifiers for CPT Code 01924

Modifier selection for CPT Code 01924 depends on the provider type and supervision arrangement. Getting this wrong is the single most common cause of denial for anesthesia claims at interventional radiology facilities.

QK and QX always appear as a pair: the anesthesiologist bills QK and each medically directed CRNA bills QX. Billing QK without the corresponding CRNA QX claim, or vice versa, will trigger a payer edit. The same pairing requirement applies regardless of procedure type, including anesthesia codes such as 00932. Verify specific modifier applicability against current CMS guidance before submission, as rules for concurrent anesthesia direction can be updated through transmittals.

Medicare reimbursement and fee schedule for CPT Code 01924

Medicare reimbursement for CPT Code 01924 follows the standard anesthesia payment methodology: total anesthesia units (base + time) multiplied by the locality-adjusted anesthesia conversion factor. Rates vary significantly by MAC region, so the figures below are illustrative ranges, not definitive payment amounts.

These estimates assume a national average anesthesia conversion factor. High-cost localities (Manhattan, San Francisco, Alaska) will pay meaningfully more. Rural MAC localities may pay less. Always confirm current rates using the official CMS Physician Fee Schedule lookup before coding a claim. Geographic Practice Cost Index (GPCI) adjustments apply to both the work and practice expense components of the fee schedule.

Billing guidelines for CPT Code 01924

Clean claims for CPT Code 01924 require more than the correct code and modifier. Payers expect specific documentation and sequencing before approving payment.

• Document anesthesia start and stop times in the operative record. Time-unit calculation depends on precise start and end timestamps. Missing or inconsistent times are a common audit trigger.
• Record the ASA physical status (P1-P6) in the anesthesia record. This supports modifier accuracy and qualifies cases for qualifying circumstance codes where applicable.
• State medical necessity explicitly. The anesthesia record should document why general or monitored anesthesia care was required rather than moderate sedation, including patient risk factors, procedure complexity, or patient intolerance of local anesthesia.
• Confirm therapeutic intent in the operative report. CPT Code 01924 covers therapeutic procedures only. The interventional radiologist’s report must reflect that the arterial procedure was therapeutic, not purely diagnostic imaging.
• Use HIPAA-compliant electronic submission for all anesthesia claims. Payers require electronic formats for standard CPT-coded claims. Review your HIPAA-compliant electronic claims submission workflow to confirm compliance before submission.
• Verify prior authorization requirements by payer. Medicare typically does not require prior auth for CPT Code 01924, but commercial payers and Medicare Advantage plans may have different rules. Always check before the procedure.

Proper anesthesia documentation also means attaching the completed digital intake and documentation forms to the patient record before claim submission. Missing pre-anesthesia evaluation notes are among the most cited deficiencies in OIG anesthesia billing audits. Using structured medical documentation forms built around anesthesia evaluation criteria reduces this risk significantly.

For anesthesia billing guidelines, the AAPC CPT code reference remains the industry’s primary coding authority alongside the AMA codebook. Cross-reference both when an edge case arises.

ICD-10 codes used with CPT Code 01924

CPT Code 01924 requires a supporting ICD-10-CM diagnosis code to establish medical necessity. The diagnosis should reflect the underlying condition driving the therapeutic arterial intervention, not the anesthesia service itself. The table below lists the most commonly paired diagnosis codes, based on standard ICD-10 crosswalk guidance for interventional radiology anesthesia. ICD-10-CM codes update annually; verify current validity against the CDC/NCHS ICD-10-CM web tool before submitting claims for the current fiscal year.

The diagnosis code should reflect the patient’s clinical condition documented in the medical record, not the procedural approach. When the underlying condition spans multiple arterial territories, code the primary site first and add secondary codes as appropriate under ICD-10-CM sequencing rules. Defaulting to an unspecified code such as B49 or F90.9 when a more specific code is available is a common audit finding, and the same discipline applies to the arterial diagnoses above.

Common billing errors and how to avoid them

Anesthesia claims for interventional radiology carry a higher audit risk than many other specialties because the modifier rules, concurrent care requirements, and therapeutic-vs-diagnostic distinction create multiple failure points. The table below maps the most frequently cited errors to specific prevention steps.

The Office of Inspector General (OIG) has historically included anesthesia modifier misuse in its work plan. Practices billing CPT Code 01924 regularly should conduct at least an annual internal audit of modifier pairs and concurrent care documentation to catch systematic errors before a payer audit does.

Related anesthesia CPT codes

CPT Code 01924 sits within the Anesthesia for Radiological Procedures section alongside several closely related codes. Selecting the wrong adjacent code is a common error; the table below clarifies when each applies.

The primary selection rule: use CPT Code 01924 only when the procedure is (a) therapeutic, (b) arterial, and (c) has no more specific code in the radiology anesthesia section. The same logic, choosing the most specific code before defaulting to an NOS code, applies to other specialty CPT coding frameworks.

How to bill CPT Code 01924 with practice management software

Manual anesthesia billing workflows for CPT Code 01924 carry compounding error risk. Time unit miscalculation, modifier oversight, and missing documentation notes often happen when coders are pulling data from separate anesthesia records, operative reports, and payer portals without a unified system.

Pabau’s claims management software keeps anesthesia documentation in one workflow instead of scattered across separate systems. Pre-anesthesia evaluation notes, anesthesia records, and consent or intake forms attach directly to the patient’s file, so coders can confirm the supervision arrangement, procedure timing, and medical necessity are documented before a claim goes out.

For anesthesia practices managing CPT billing documentation alongside clinical notes, structured practice management software that connects documentation to claims helps ensure what the anesthesia record says matches what gets submitted to the payer. Reviewing comparable CPT billing documentation requirements across specialty billing workflows reduces this risk further.

Reduce anesthesia claim denials with Pabau

Practice management software like Pabau can keep pre-anesthesia evaluation notes, anesthesia records, and consent forms organized and attached to each patient file ahead of claim submission. See how it fits into the CPT Code 01924 billing workflow.

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Conclusion

CPT Code 01924 covers a specific and consequential billing scenario: anesthesia for therapeutic arterial interventional radiology where no narrower code applies. Five base units, five core modifiers, and an annual Medicare conversion factor combine into a payment formula that is straightforward in principle but prone to error in execution.

Getting CPT Code 01924 right means confirming the procedure is therapeutic, pairing the correct modifier to the supervision arrangement, documenting anesthesia time precisely, and attaching medical necessity to every claim. Practices that keep this documentation organized with purpose-built practice management tools reduce denial rates and lower audit risk, whether the setting is a hospital-based interventional radiology suite, a general practice coordinating referrals for IR procedures, or a physical therapy practice managing post-procedure care.

Continue your research

Need to understand anesthesia billing documentation requirements? Medical forms for your healthcare practice covers the documentation structures that reduce claim deficiencies in anesthesia and procedural settings.

Want a compliance checklist for your billing workflows? HIPAA compliance for medical offices outlines the data and documentation standards that apply to CPT-coded claim submissions.

Looking for a CPT code resource for adjacent procedure categories? Procedure codes and fee schedule reference provides a structured guide to procedure code billing across specialties.

Frequently Asked Questions