$405.66–$429.16
Choose 31040 for exploration of the pterygomaxillary fossa behind the upper jaw. Code 31020 concerns a maxillary sinus procedure.
On this page
CMS RVU26D · Effective 2026-10-01
31040 Fossa exploration Medicare reimbursement rates in Michigan
Operative exploration of the pterygomaxillary fossa behind the upper jaw, reported when the surgeon directly investigates this deep space. Compare 31040 office and facility rates across CMS payment localities in Michigan.
Amounts below use the non-QP conversion factor for participating physicians. These are base physician payments before claim-level adjustments, not patient costs or total hospital charges.
What does Medicare pay for 31040 in Michigan?
Michigan has 2 payment localities in this comparison. Use the service location to choose the applicable amount. These are the supported base rates for the 2 payment areas shown below, using the same CMS release.
Office / nonfacility
No supported rate
Facility setting
$697.01–$742.11
2 of 2 localities have a supported rate.
These are locality ranges, not averages or address-specific quotes. A facility-setting amount covers the physician service; it does not include a hospital’s separate bill. Choose a locality below to inspect its calculation, compare other payment areas, or price a percentage of Medicare.
Sinus and skull base surgery
About 31040: Pterygomaxillary fossa exploration
Operative exploration of the pterygomaxillary fossa behind the upper jaw, reported when the surgeon directly investigates this deep space.
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.
CMS billing rules for 31040
- Global period
- Major surgery with a 90-day global period: the day-before preoperative visit and 90 days of related postoperative care are included.
- Multiple procedures
- Standard multiple procedure reduction: the highest-valued procedure is paid in full and others at 50% when performed in the same session.
- Bilateral procedures
- Bilateral procedure with modifier 50 is paid at 150%.
- Assistant at surgery
- Statutory restriction: assistant at surgery is not paid.
- Co-surgeons
- Co-surgeons paid only with supporting documentation.
- Team surgery
- Team surgery not permitted.
Where the value comes from
- Work RVU9.53 · 44%
- Practice expense (office) RVU10.65 · 49%
- Malpractice RVU1.43 · 7%
144
Medicare services in 2024 · #4594 by national volume
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 compared with similar codes
Office rates for Michigan, from the same CMS release.
$618.22–$655.12
Code 31030 describes a radical maxillary sinus procedure; 31040 targets exploration of the adjacent pterygomaxillary fossa.
No office rate
Code 31050 targets the sphenoid sinus. Use 31040 when the operative exploration is of the pterygomaxillary fossa.
Compare 31040 by payment locality
Find the payment area for your service address, then open its rate page for calculation inputs, release history and the percentage-of-Medicare tool. A city may cross payment-area boundaries; the ZIP lookup above helps resolve the location.
2 of 2 payment localities
Detroit →
Office / nonfacility
Unavailable
Facility
$742.11
Rest Of Michigan →
Office / nonfacility
Unavailable
Facility
$697.01
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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 indices and the applicable conversion factor. Unavailable or separately priced services are labeled rather than assigned a made-up amount.
Source: RVU26D. Effective 2026-10-01 through the day before 2027-01-01.
3,49631020,,Exploration maxillary sinus,A,,2.99,9.57,,6.43,,0.37,12.93,9.79,0,090,0.10,0.76,0.14,2,1,1,0,0,9,,33.4009,09,0,99,0.00,0.00,0.00
3,49731030,,Exploration maxillary sinus,A,,5.86,12.89,,7.56,,0.78,19.53,14.20,0,090,0.10,0.76,0.14,2,1,1,0,0,9,,33.4009,09,0,99,0.00,0.00,0.00
3,49831032,,Explore sinus remove polyps,A,,6.52,9.07,NA,9.07,,0.93,16.52,16.52,0,090,0.10,0.76,0.14,2,1,1,0,0,9,,33.4009,09,0,99,0.00,0.00,0.00
3,49931040,,Exploration behind upper jaw,A,,9.53,10.65,NA,10.65,,1.43,21.61,21.61,0,090,0.10,0.76,0.14,2,1,1,1,0,9,,33.4009,09,0,99,0.00,0.00,0.00
3,50031050,,Exploration sphenoid sinus,A,,5.24,8.26,NA,8.26,,0.78,14.28,14.28,0,090,0.10,0.76,0.14,2,1,1,0,0,9,,33.4009,09,0,99,0.00,0.00,0.00
3,50131051,,Sphenoid sinus surgery,A,,7.07,10.90,NA,10.90,,1.05,19.02,19.02,0,090,0.10,0.76,0.14,2,1,1,0,0,9,,33.4009,09,0,99,0.00,0.00,0.00
3,50231070,,Exploration of frontal sinus,A,,4.29,8.35,NA,8.35,,0.62,13.26,13.26,0,090,0.10,0.76,0.14,2,1,1,0,0,9,,33.4009,09,0,99,0.00,0.00,0.00