Free ENT tool
Antigen preparation unit calculator
Vial composition in, units out under both Medicare aliquot and clinical-dose methods, plus which administration code applies. Numbers and dropdowns only. No patient data. Runs in your browser.
Educational only. Not billing or legal advice. Check the current article and your payer. Do not enter patient information. This tool runs entirely in your browser; nothing is sent anywhere.
Methodology
- Medicare aliquot method: one billable unit = one 1 cc aliquot from a multidose vial, capped at 10 units per vial. A 6 cc fill is 6 units.
- Clinical-dose method (some commercials): a unit is a planned clinical dose drawn from the vial. A 5 cc vial drawn ten times is 10 units.
- Daily MUE for 95165 under Medicare is 30 units across all vials on the same day.
- 95165 = prep of multidose non-venom antigen vials. 95144 = single-dose vials prepared for another practice to inject. 95115 = one injection. 95117 = two or more injections.
- If 95144 is billed with an injection you gave, the MAC re-prices 95144 to 95165.
- Vials under 10 cc return their filled volume in units, not 10. Only a full 10 cc vial yields 10 units under the Medicare method.
Worked example (illustrative)
Three vials, 5 cc each, 10 doses drawn per vial. Prepared here, one injection today.
Medicare aliquot method: 5 units per vial, 15 total. Within the 30-unit daily MUE.
Clinical-dose method: 10 units per vial, 30 total. No 10-per-vial cap.
Codes: 95165 (prep) + 95115 (one injection). Both can post today.
Same vials. Same doses drawn. Different payer, different unit count. That is why the rule you live under matters more than the math.
Sources
- CMS Billing and Coding: Allergy Immunotherapy (Article A57472).
- AAOA: Understanding Billable Units, Avoiding Denials and Optimizing Compliance.
- CMS definition: one billable unit = one 1 cc aliquot from a multidose vial, effective 1 January 2021.
- Daily MUE of 30 units for 95165 per CMS NCCI edits.