CPT code 64421: Intercostal nerve block, each additional nerve2026 Medicare rate & RVUs in Michigan
Reports anesthetic blockade of each intercostal nerve beyond the first, such as for chest wall pain managed with a regional block.
Medicare pays $33.80–$35.62 for 64421 in the office in Michigan, from Rest of Michigan to Detroit, MI. Which amount applies depends on the service address.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
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On this page 9 sections
What 64421 covers
This add-on represents anesthetic blockade of additional intercostal nerves after the first nerve is blocked. Physicians, anesthesiologists, and pain specialists may use multiple intercostal blocks for chest wall analgesia, including pain related to rib injuries or thoracic procedures. The service targets individual nerves supplying the chest wall rather than a broader thoracic regional approach.
Report 64421 with 64420 for the first intercostal nerve; use 64421 for each additional nerve treated. The procedure note should identify the nerves and side treated, the anesthetic administered, and the clinical reason for blocking multiple nerves. CMS classifies 64421 as an add-on code: it is billed only with a primary procedure and paid within that procedure’s global period. For a bilateral procedure reported with modifier 50, CMS pays 150%.
This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.
Where 64421 pays more and less in Michigan
| Payment locality | Office | Facility |
|---|---|---|
| Detroit, MI | $35.62 | $22.73 |
| Rest of Michigan | $33.80 | $21.61 |
How the 64421 rate is calculated
Each of 64421’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.
How the rate is built · 64421
RVUs × geographic indexes × conversion factor
Work0.49
0.49 RVUs× 1.000 GPCI
Practice expense0.51
0.51 RVUs× 1.000 GPCI
Malpractice0.05
0.05 RVUs× 1.000 GPCI
Adjusted RVUs
1.0500
Conversion factor
$33.4009
Medicare rate
$35.07
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 64421
The CMS indicators that decide how 64421 is paid alongside other services.
CMS payment indicators · 64421
Intercostal nerve block, each additional nerve
| Rule | CMS value | What it means |
|---|---|---|
| Global period | ZZZ | Add-on code: falls within the primary procedure’s global period. |
| Multiple procedures | 0 | No multiple-procedure reduction. |
| Bilateral (modifier 50) | 1 | Bilateral with modifier 50 pays 150% of the fee schedule amount. |
| Assistant at surgery (80/81/82/AS) | 1 | Not paid (statutory restriction). |
| Co-surgeons (62) | 0 | Not permitted. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 0 | Physician service: no professional/technical split. |
What modifiers do to the payment
Modifier 50 · payment effect
With and without the modifier
64421 without 50 · national office
$35.07
Intercostal nerve block, each additional nerve
64421-50 · Bilateral: 150%
$52.61
Both sides on one line with modifier 50 are paid at 150% of the fee schedule amount (subject to multiple-procedure rules with other procedures).
64421 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 64420Intercostal blockSingle nerve
- 64420 represents the first intercostal nerve blocked. Use 64421 only for additional intercostal nerves and report it with 64420.
- 64461Paravertebral blockThoracic, single site
- 64461 describes a thoracic paravertebral block. Choose it when that regional approach is performed rather than individual intercostal nerve blocks.
- 64462Paravertebral blockAdditional thoracic injection site
- 64462 represents an additional thoracic paravertebral injection site when paired with 64461; it is not the add-on for additional intercostal nerves.
64421 billing questions
When is 64421 reported instead of 64420?
64420 represents the initial intercostal nerve block. Report 64421 for each additional intercostal nerve blocked in the same service.
Which primary code must accompany 64421?
Report 64421 with 64420 for the initial intercostal nerve block. CMS treats 64421 as an add-on code and pays it within the primary procedure’s global period.
What should the procedure note identify?
Document the clinical reason for the blocks, the intercostal nerves and side treated, and the anesthetic administered. The record should support that additional nerves beyond the first were blocked.
How is a bilateral procedure handled?
CMS pays a bilateral procedure reported with modifier 50 at 150%. The documentation should support treatment on both sides.
Is 64421 reported for every nerve injected?
Use 64420 for the first intercostal nerve and 64421 for each additional nerve. The documented nerve count should support the reported additional services.
Where these rates come from
FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.
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