CPT code 31298: Sinus dilation, frontal and sphenoid2026 Medicare rate & RVUs in Missouri
Endoscopic dilation of frontal and sphenoid sinus openings is reported when both drainage pathways are treated during the same operative session.
Medicare pays $2,578.96–$2,831.39 for 31298 in the office in Missouri, from Rest of Missouri to Metropolitan St. Louis, MO. 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 31298 covers
An otolaryngologist uses a nasal endoscope to access and enlarge the frontal and sphenoid sinus openings, commonly with a balloon catheter passed through the nasal cavity. The procedure may be performed for obstructed sinus drainage, including in patients with chronic rhinosinusitis, when the operative plan is dilation at both sites. It is typically performed in an operating or procedural setting; the record should identify each sinus treated and the dilation performed.
Report 31298 when both frontal and sphenoid openings are dilated during the operative session; single-sinus dilation codes distinguish treatment of only one site. Document the treated anatomy, laterality, and technique. CMS assigns a 0-day global period, so same-day preoperative and postoperative care is included. Related endoscopies performed together are subject to endoscopy-family pricing. For bilateral work, modifier 50 is paid at 150%. Assistant-at-surgery payment requires documented medical necessity; 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 31298 pays more and less in Missouri
The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.
3 payment localities
$2578.96 to $2831.39
| Payment locality | Office | Facility |
|---|---|---|
| Metropolitan Kansas City, MO | $2,794.49 | $212.34 |
| Metropolitan St. Louis, MO | $2,831.39 | $213.49 |
| Rest of Missouri | $2,578.96 | $208.55 |
How the 31298 rate is calculated
Each of 31298’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 · 31298
RVUs × geographic indexes × conversion factor
Work4.39
4.39 RVUs× 1.000 GPCI
Practice expense83.78
83.78 RVUs× 1.000 GPCI
Malpractice0.62
0.62 RVUs× 1.000 GPCI
Adjusted RVUs
88.7900
Conversion factor
$33.4009
Medicare rate
$2,965.67
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 31298
The CMS indicators that decide how 31298 is paid alongside other services.
CMS payment indicators · 31298
Sinus dilation, frontal and sphenoid
| 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) | 0 | Not paid without supporting documentation. |
| 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
31298 without 50 · national office
$2,965.67
Sinus dilation, frontal and sphenoid
31298-50 · Bilateral: 150%
$4,448.51
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).
31298 compared with similar codes
Compare codes · National
5 codes, side by side
How to choose
- 31296Sinus dilationFrontal sinus
- 31296 describes dilation of the frontal sinus opening alone. Choose 31298 when the sphenoid opening is also dilated in the session.
- 31297Sinus dilationSphenoid ostium
- 31297 describes dilation of the sphenoid sinus opening alone. Choose 31298 when the frontal opening is also dilated in the session.
- 31276Frontal sinus endoscopyTissue removal when performed
- 31276 is frontal sinus endoscopic surgery involving tissue removal; 31298 describes dilation of the frontal and sphenoid openings.
- 31287SphenoidotomyWithout tissue removal
- 31287 is endoscopic sphenoid sinus surgery without tissue removal, not dilation of both the sphenoid and frontal openings.
31298 billing questions
When should I choose 31298 over 31296 or 31297?
Use 31298 when the frontal and sphenoid sinus openings are both dilated. Codes 31296 and 31297 describe dilation at the frontal and sphenoid sites, respectively, when only one of those sites is treated.
Does 31298 include maxillary sinus dilation?
No. This code identifies dilation of the frontal and sphenoid openings. The maxillary sinus dilation code is 31295.
How should I report bilateral dilation?
CMS identifies this as a bilateral procedure; modifier 50 is paid at 150%. The operative documentation should support treatment on both sides.
How does payment work when related endoscopies are performed together?
CMS applies endoscopy-family pricing when related endoscopies are performed together. The same-day preoperative and postoperative care is included in the 0-day global period.
What documentation supports reporting 31298?
Document endoscopic dilation of both the frontal and sphenoid sinus openings, along with the treated side or sides and the technique performed. Assistant-at-surgery payment requires documentation of medical necessity.
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
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