CPT Code 01430: Anesthesia for veins of the knee and popliteal area

Key Takeaways

CPT Code 01430 describes anesthesia for procedures on the veins of the knee and popliteal area, not otherwise specified, billed by anesthesiologists and CRNAs

CMS assigns 01430 a value of 3 base units; reimbursement is calculated as (base units + time units) multiplied by the anesthesia conversion factor

Modifier selection (AA, QZ, QK, QX, QY) depends on who delivers care and the supervision arrangement; choosing the wrong modifier is the leading cause of claim denial

The most common miscode is treating 01430 as a knee-joint code; it is a venous code, distinct from 01400, 01402, and the arteriovenous fistula code 01432

Practice management software like Pabau can capture anesthesia encounter details and time documentation accurately, reducing the manual re-entry that leads to modifier and charge errors

CPT Code 01430 is the anesthesia code for procedures on the veins of the knee and popliteal area, not otherwise specified. Anesthesiologists and certified registered nurse anesthetists (CRNAs) report it for venous procedures in the knee and popliteal region, such as vein ligation, venous thrombectomy, or varicose vein surgery, when no more specific anesthesia code applies.

This reference covers the exact code descriptor, the CMS base unit value, the reimbursement formula with a worked example, Medicare fee schedule data, modifier guidance for each supervision scenario, the related knee and popliteal codes 01430 is most often confused with, documentation requirements, and the most common denial reasons.

CPT Code 01430: Definition and clinical scope

CPT Code 01430 describes anesthesia services for procedures performed on the veins of the knee and popliteal area. Per the American Medical Association’s (AMA) CPT code set, it is a venous (vascular) code classified within the anesthesia section of the CPT manual, in the knee and popliteal range (01320-01444).

The descriptor ends in “not otherwise specified,” so 01430 is the default for venous work in this region when a more specific code does not apply. The one carve-out is the arteriovenous fistula code 01432. Both anesthesiologists and CRNAs report 01430, with modifier selection determining who delivered care and whether physician supervision was present.

These venous procedures are frequently scheduled within vascular surgery, general surgery, or dermatology practices, where anesthesiologists or CRNAs deliver anesthesia alongside the treating surgeon. Practices using dermatology-focused practice management software to schedule these cases benefit from keeping the surgical and anesthesia records tied to the same patient encounter.

Anesthesia base units for CPT 01430

CPT 01430 carries 3 base units. CMS assigns each anesthesia code a base unit value that reflects the relative difficulty and risk of providing anesthesia for that procedure.

These base unit values are published annually through the CMS Anesthesiologists Information Center, not the standard RVU-based Physician Fee Schedule Look-Up Tool, which does not include anesthesia base units or the anesthesia conversion factor.

The value of 3 sits at the lower end of the knee and popliteal cluster, below the arteriovenous fistula code 01432 (6 base units) and the arterial code 01440 (8 base units).

Base units are only one component of the reimbursement calculation. Time units, which reflect how long anesthesia was administered, are added before the conversion factor is applied. Accurate time capture protects that base unit value from underpayment: encounter documentation software that records start-to-finish anesthesia time removes the most common source of underpayment, which is inaccurate time unit recording.

How the anesthesia reimbursement formula works

Anesthesia reimbursement does not use the standard relative value unit (RVU) structure. Instead, CMS calculates payment using a formula defined in the AMA’s CPT coding resources: (base units + time units) x anesthesia conversion factor (ACF).

• Base units: assigned by CMS per code (3 for CPT 01430)
• Time units: each 15-minute increment of anesthesia time equals 1 time unit
• Anesthesia conversion factor: a dollar-per-unit rate set by CMS, varying by geographic locality and updated annually

Worked example. A 45-minute popliteal vein ligation produces 3 time units (45 min / 15 = 3). Add 3 base units for a total of 6 units. If the applicable Medicare ACF for that locality is $23.00, the Medicare allowed amount is 6 x $23.00, or $138.00.

Private payer rates and locality-adjusted ACF values will produce different totals. Confirm the ACF for your specific locality through the CMS Anesthesiologists Information Center; the standard Physician Fee Schedule Look-Up Tool does not publish anesthesia conversion factors.

The same base-unit-plus-time-unit formula applies across the anesthesia code set. Upper arm and elbow surgery billed under 01710 and a vulvectomy billed under 00932 use the identical calculation, just with different base units and time totals for the procedure and case length.

Practices using HIPAA-compliant clinical documentation workflows that capture procedure start and stop times automatically have a structural advantage here: time unit calculation becomes a byproduct of good documentation rather than a separate manual step.

Fee schedule and Medicare reimbursement rates

Medicare reimbursement for CPT 01430 varies by geographic locality because the anesthesia conversion factor (ACF) differs by region. The table below shows representative 2026 Medicare ACF values for selected localities; actual payment is the formula output using the locality-specific ACF.

Verify current rates through the CMS Anesthesiologists Information Center, which publishes anesthesia conversion factors. The standard Physician Fee Schedule Look-Up Tool covers RVU-based specialties and does not include anesthesia rates.

Note: ACF figures above are illustrative ranges based on typical regional variation, not exact current-year rates. Private payer rates may differ significantly and are negotiated separately from Medicare.

For surgical procedures billed alongside 01430, surgical practice management workflows that link procedure scheduling with billing documentation help ensure anesthesia and procedure codes are submitted together on the same claim.

Modifiers for CPT Code 01430

The anesthesia modifiers reported with CPT Code 01430 communicate the provider type and supervision arrangement to the payer. Selecting the wrong modifier is the most common denial trigger for these claims. The five modifiers most relevant to this code are listed below.

CRNA billing and supervision scenarios

CRNA eligibility to bill CPT 01430 independently depends on whether the state has opted out of the Medicare physician supervision requirement.

In non-opt-out states, a CRNA must bill under physician supervision (modifier QX) unless the supervising anesthesiologist also bills separately using QK or QY. In states that have exercised the opt-out, a CRNA practicing independently uses modifier QZ and receives the full allowed amount.

Practices managing both anesthesiologist and CRNA providers benefit from digital anesthesia documentation that captures provider role and supervision status at the encounter level, feeding accurate modifier selection downstream.

Related codes in the knee and popliteal anesthesia series

CPT 01430 sits in a cluster of knee and popliteal anesthesia codes split across three anatomical targets: the knee joint, the veins, and the arteries. Billing across those boundaries is the most common audit flag for this code.

The same vein-versus-artery distinction carries into other regions of the body. Anesthesia for arterial interventional radiology elsewhere in the body, for example, is billed under 01924 rather than a venous code. The table below compares the knee and popliteal codes 01430 is most often confused with, including base units and the distinction that decides which code applies.

For the adjacent codes in this range, see Pabau’s references on 01400 for knee-joint procedures and 01432 for arteriovenous fistula billing. The AAPC CPT code lookup provides searchable descriptors across the full anesthesia range.

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Documentation requirements for CPT 01430

CMS requires specific documentation elements to support compliant billing of CPT 01430. Missing any component gives auditors grounds to recoup payment. Three documents anchor the anesthesia record.

• Pre-anesthesia evaluation: performed and documented before the procedure begins; includes patient history, physical status (ASA classification), and planned anesthetic technique
• Intraoperative anesthesia record: continuous record of agent(s) administered, monitoring data, and times (induction start, incision, procedure end, emergence); this is the source document for time unit calculation
• Post-anesthesia note: documents patient recovery status and any complications; required before the patient leaves the post-anesthesia care unit (PACU)

Incomplete intraoperative time recording draws the most audit attention. When a regional nerve block supplements the anesthesia, the injected agent needs its own charge capture too; ropivacaine, for example, is billed separately under J2795.

Practices using standardized medical forms for anesthesia encounters reduce this risk by prompting providers to capture start and stop times as part of the standard workflow rather than as a retrospective addition.

For practices managing compliance documentation at scale, compliance documentation tools that link pre-operative consent, intraoperative records, and post-anesthesia notes in a single patient file make audit response faster and more complete. Maintaining time-saving practice features across a surgical or anesthesia practice creates a meaningful downstream reduction in denial rate.

Common billing errors and denial reasons

Three failure patterns account for the majority of CPT 01430 denials. Knowing them in advance is more efficient than learning them from a remittance advice.

• Coding a venous procedure as a joint or arterial procedure (or the reverse). CPT 01430 covers the veins of the knee and popliteal area, not the knee joint itself. Using 01430 for an arthroscopic or open joint case that belongs to 01400 or 01402, reaching for it when the venous work is an arteriovenous fistula (01432), or applying it to arterial work that belongs to 01440, all produce a code-to-procedure mismatch that automated claim edits flag before a human reviewer sees it.
• Incorrect modifier for the supervision arrangement. A CRNA billing QZ in a non-opt-out state, or an anesthesiologist billing AA when they directed a CRNA, produces an automatic denial. Verify state opt-out status before each claim cycle.
• Incomplete time documentation. If the intraoperative record does not capture a clear anesthesia start time and end time, payers reduce or deny time units. The claim may process at base units only, underpaying by 30-60% depending on case length.

Code accuracy is the first line of defense. The claim edit that catches a wrong code costs nothing to fix in-house, while the same error caught on a remittance advice costs a full resubmission cycle and delays payment.

Conclusion

Most CPT 01430 denials are preventable. The formula is not complicated, but it requires the right code for a venous procedure, accurate time documentation, and modifier selection that reflects the actual supervision arrangement on each case.

Pabau brings scheduling, encounter documentation, and billing workflows into a single environment, reducing the manual re-entry that creates time unit errors and modifier mismatches. To see how it supports anesthesia and surgical practice documentation, book a demo.

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