A9558 Xe133 xenon 10mci

What A9558 is

Xenon xe-133 gas, diagnostic, per 10 millicuries

HCPCS Level II long description, CMS October 2026 file. See the A codes page for the full section.

Medicare payment for A9558 (CY2026)

This code has no Physician Fee Schedule rate: Carrier-priced - the Medicare contractor sets the price. It may be paid under a different fee schedule (clinical laboratory, DMEPOS, anesthesia) or not paid at all - check the relevant CMS schedule.

Medically Unlikely Edit (MUE)

Medicare caps A9558 at 7 units per date of service for practitioner claims (MAI 3 - date of service edit (clinical): units above the MUE may pay with documentation on appeal), rationale: Prescribing Information. Units above the cap are denied unless the edit's adjudication rules allow an appeal with documentation.

A9558 is bundled into these codes

A9558 appears as a Column 2 code in 34 active edits. Reported with one of these Column 1 codes on the same date of service, A9558 is the code that denies.

Data: CMS CY2026 Physician Fee Schedule RVU file (October release, RVU26D) and Medicare NCCI PTP practitioner edits v32.3 (2026 Q4). Verify against the official files before billing or contracting decisions.