CPT code 31256: Maxillary antrostomy, without tissue removal2026 Medicare rate & RVUs in California
Report this procedure for endoscopic creation or enlargement of a maxillary sinus opening for drainage, without removing tissue from the sinus.
CMS doesn’t publish an office rate for 31256 in California.
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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What 31256 covers
An otolaryngologist typically performs this endoscopic procedure through the nasal passage to create or enlarge an opening into a maxillary sinus, improving access and drainage. It is used in surgical treatment of conditions such as chronic maxillary sinusitis when an operative antrostomy is performed. The code describes the sinus opening, not removal of tissue from within the maxillary sinus.
Select this code when the operative report supports a surgical maxillary antrostomy without maxillary sinus tissue removal; use the tissue-removal sibling when tissue is removed from the sinus. Document the side, the work performed, and whether sinus tissue was removed. The procedure has a 0-day global period, so same-day preoperative and postoperative care is included. When related endoscopies are performed together, endoscopy family pricing applies. For bilateral work, modifier 50 is paid at 150%. Medicare does not pay an assistant at surgery; co-surgeons and team surgery are not permitted.
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 31256 pays more and less in California
The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.
29 of 29 payment localities
| Payment locality | Office | Facility |
|---|---|---|
| Bakersfield, CA | Unavailable | $152.51 |
| Chico, CA | Unavailable | $151.26 |
| El Centro, CA | Unavailable | $151.33 |
| Fresno, CA | Unavailable | $151.26 |
| Hanford, CA | Unavailable | $151.26 |
| Los Angeles, CA | Unavailable | $158.75 |
| Madera, CA | Unavailable | $151.26 |
| Marin County, CA | Unavailable | $169.69 |
| Merced, CA | Unavailable | $151.26 |
| Modesto, CA | Unavailable | $151.26 |
| Napa, CA | Unavailable | $163.74 |
| Oxnard, CA | Unavailable | $156.81 |
| Redding, CA | Unavailable | $151.26 |
| Rest of California | Unavailable | $151.26 |
| Riverside, CA | Unavailable | $155.91 |
| Sacramento, CA | Unavailable | $155.66 |
| Salinas, CA | Unavailable | $155.01 |
| San Benito County, CA | Unavailable | $173.50 |
| San Diego, CA | Unavailable | $156.37 |
| San Francisco, CA | Unavailable | $169.20 |
| San Luis Obispo, CA | Unavailable | $152.85 |
| Santa Clara County, CA | Unavailable | $171.50 |
| Santa Cruz, CA | Unavailable | $156.07 |
| Santa Maria, CA | Unavailable | $154.97 |
| Santa Rosa, CA | Unavailable | $157.47 |
| Stockton, CA | Unavailable | $151.26 |
| Vallejo, CA | Unavailable | $163.04 |
| Visalia, CA | Unavailable | $151.26 |
| Yuba City, CA | Unavailable | $151.26 |
How the 31256 rate is calculated
Each of 31256’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 · 31256
RVUs × geographic indexes × conversion factor
Work3.03
3.03 RVUs× 1.000 GPCI
Practice expense1.11
1.11 RVUs× 1.000 GPCI
Malpractice0.43
0.43 RVUs× 1.000 GPCI
Adjusted RVUs
4.5700
Conversion factor
$33.4009
Medicare rate
$152.64
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 31256
The CMS indicators that decide how 31256 is paid alongside other services.
CMS payment indicators · 31256
Maxillary antrostomy, without tissue removal
| Rule | CMS value | What it means |
|---|---|---|
| Global period | 000 | Same-day global: pre- and post-op care on the day of the procedure is included. |
| Multiple procedures | 3 | Endoscopy family rules apply. |
| 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
31256 without 50 · national facility
$152.64
Maxillary antrostomy, without tissue removal
31256-50 · Bilateral: 150%
$228.96
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).
31256 compared with similar codes
Compare codes · National
5 codes, side by side
How to choose
- 31267Sinus endoscopyMaxillary tissue removal
- Choose 31256 when the maxillary antrostomy is performed without removing tissue from within the sinus. Choose 31267 when sinus tissue is removed.
- 31233Sinus endoscopyMaxillary sinus
- 31233 is diagnostic maxillary sinus endoscopy. This code describes an operative antrostomy, not inspection alone.
- 31231Nasal endoscopyDiagnostic, without sinusoscopy
- 31231 describes diagnostic nasal endoscopy. It does not represent surgical opening of the maxillary sinus.
- 31254EthmoidectomyPartial, anterior ethmoid
- 31254 describes partial ethmoidectomy, an operation on the ethmoid sinus. This code describes a maxillary sinus antrostomy.
31256 billing questions
How does this differ from 31267?
This code describes a maxillary antrostomy without removal of tissue from the maxillary sinus. Report 31267 when tissue is removed from within the sinus.
Can diagnostic nasal endoscopy be reported instead?
No, when the service includes a surgical maxillary antrostomy. Diagnostic endoscopy codes describe examination without this operative opening.
What should the operative report document?
Document the side, the maxillary sinus opening performed, and whether tissue was removed from within the sinus. These details support selection between this code and 31267.
How is bilateral work reported?
Use modifier 50 for bilateral performance; CMS pays the bilateral procedure at 150%.
Can an assistant, co-surgeon, or surgical team be paid?
Medicare does not pay an assistant at surgery for this code. Co-surgeons and team surgery are not permitted.
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.
CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027
Show the CMS file lines behind this rate
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