Billing code 31040: Fossa explorationMedicare rate & RVUs in Oklahoma
Operative exploration of the pterygomaxillary fossa behind the upper jaw, reported when the surgeon directly investigates this deep space.
CMS doesn’t publish an office rate for 31040 in Oklahoma.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
On this page 9 sections
What 31040 covers
This operation gives the surgeon access to and permits direct inspection of the pterygomaxillary fossa, a deep space behind the upper jaw. It is distinct from opening or irrigating a paranasal sinus. Otolaryngologists and oral and maxillofacial or head and neck surgeons may perform it in an operating room, generally in a facility setting. The operative report should identify the fossa as the target and describe the approach and exploration performed.
Report 31040 when the documented service is exploration of this space, rather than a maxillary or sphenoid sinus procedure. The 90-day global period includes the day-before preoperative visit and 90 days of related postoperative care. When multiple procedures occur in the same session, the highest-valued procedure is paid in full and other procedures are subject to the standard 50% reduction. Modifier 50 is paid at 150% for bilateral procedures. Medicare does not pay an assistant at surgery; co-surgeons require supporting documentation, and team surgery is 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.
31040 in Oklahoma
| Payment locality | Office | Facility |
|---|---|---|
| Oklahoma | Unavailable | $673.08 |
How the 31040 rate is calculated
Each of 31040’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 · 31040
RVUs × geographic indexes × conversion factor
Work9.53
9.53 RVUs× 1.000 GPCI
Practice expense10.65
10.65 RVUs× 1.000 GPCI
Malpractice1.43
1.43 RVUs× 1.000 GPCI
Adjusted RVUs
21.6100
Conversion factor
$33.4009
Medicare rate
$721.79
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 31040
31040 has a 90-day global period: related visits in that window are included in the surgery payment.
CMS payment indicators · 31040
Fossa exploration
| Rule | CMS value | What it means |
|---|---|---|
| Global period | 090 | Major surgery: the day before, the day of, and 90 days after are included. |
| Multiple procedures | 2 | Standard reduction: highest-valued procedure at 100%, others at 50%. |
| 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) | 1 | Permitted with supporting documentation. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 0 | Physician service: no professional/technical split. |
| Split (54/55/56) | 0.10/0.76/0.14 | Share of the payment for pre-op, the procedure itself, and post-op care. |
Global surgery period · 31040
Fossa exploration
90-day global period ends
Dec 30, 2026
Covers Sep 30, 2026 through Dec 30, 2026 (92 days, including the day before surgery).
Visit on Oct 31, 2026
Day 30 of the 90-day post-op period: related follow-up care is included in the surgical payment.
Pre-op dayGlobal period
What modifiers do to the payment
Modifier 50 · payment effect
With and without the modifier
31040 without 50 · national facility
$721.79
Fossa exploration
31040-50 · Bilateral: 150%
$1,082.69
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).
31040 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 31020Maxillary sinusotomy
- Choose 31040 for exploration of the pterygomaxillary fossa behind the upper jaw. Code 31020 concerns a maxillary sinus procedure.
- 31030Sinus exploration
- Code 31030 describes a radical maxillary sinus procedure; 31040 targets exploration of the adjacent pterygomaxillary fossa.
- 31050Sphenoid sinus surgery
- Code 31050 targets the sphenoid sinus. Use 31040 when the operative exploration is of the pterygomaxillary fossa.
31040 billing questions
How does 31040 differ from maxillary sinus surgery?
31040 targets the pterygomaxillary fossa behind the upper jaw. Codes for maxillary sinus procedures target the sinus itself.
What documentation supports 31040?
The operative report should identify the pterygomaxillary fossa as the site explored and describe the surgical access and exploration.
Does the 90-day global period include related postoperative care?
Yes. It includes the day-before preoperative visit and 90 days of related postoperative care.
How is a bilateral procedure reported?
Use modifier 50 for a bilateral procedure; CMS pays it at 150%.
Can an assistant or co-surgeon be paid?
Medicare does not pay an assistant at surgery for this code. Co-surgeons are paid only with supporting documentation.
What happens when other procedures are performed in the same session?
The highest-valued procedure is paid in full, and other procedures are subject to the standard multiple procedure reduction.
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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