CPT code 31298 – Frontal and sphenoid balloon dilation

Key takeaways

CPT code 31298 reports endoscopic dilation of both the frontal and sphenoid sinus ostia on the same side, replacing 31296 plus 31297 for that side.

Many commercial plans and some state Medicaid programs require prior authorization for 31298, and the approval should name this code rather than 31296 or 31297.

Medicare gives 31298 bilateral indicator 1, so modifier 50 pays 150% of the single-side fee schedule amount. Some commercial payers want RT and LT lines instead.

Pabau, the practice management platform we build, submits and tracks 31298 claims through Claim.MD once your coder has chosen the code.

CPT code 31298: official descriptor and procedure scope

CPT code 31298 describes “Nasal/sinus endoscopy, surgical; with dilation of frontal and sphenoid sinus ostia (eg, balloon dilation).” It is the only combination code in the 31295-31298 balloon dilation family, published in the American Medical Association CPT code set. The AMA added it for CY2018 because surgeons so often dilate these two ostia together.

The code covers two sites on one side of the nose: the frontal sinus ostium and the sphenoid sinus ostium. It has no maxillary component.

If only one of the two ostia is dilated, report 31296 for the frontal or 31297 for the sphenoid instead. When the maxillary ostium on that side is dilated as well, report 31295 in addition to 31298.

What the procedure involves

Balloon ostial dilation uses a flexible catheter advanced endoscopically into the target sinus. Once positioned at the sinus ostium, a small balloon is inflated to widen the natural drainage pathway. Fluoroscopic or image guidance may be used to confirm catheter placement. The technique is distinct from traditional functional endoscopic sinus surgery (FESS) because it does not remove tissue.

• Endoscopic guidance: rigid nasal endoscope used to visualize approach
• Balloon catheter placement: guidewire and catheter advanced to the ostium
• Dilation: balloon inflated to widen the ostium, held briefly, then deflated
• Fluoroscopy: may be used to confirm position, and CPT includes it in 31295-31298 when performed
• Site confirmation: post-dilation endoscopic check of ostial patency

The operative report must document each sinus site accessed, the side, and the dilation technique applied. For 31298, it must show that both the frontal and the sphenoid ostia on the same side were dilated. Coders cannot assume a site was treated unless the operative note describes it explicitly.

CPT 31298 vs 31295, 31296 and 31297: choosing the right code

The four codes in this family are told apart by which sinus ostia were dilated on each side, not by technique. Three cover a single ostium, and 31298 covers the frontal and sphenoid ostia together.

Key rule: 31298 replaces 31296 and 31297 when both are dilated on the same side. The CPT parenthetical bars reporting 31296 or 31297 with 31298 on that side.

It does not replace 31295, because 31298 has no maxillary component. Frontal, maxillary and sphenoid dilation on one side is therefore 31295 plus 31298. The matrix below maps all seven same-side combinations to the codes they take.

Bundling and NCCI edits

Reporting 31298 with 31296 or 31297 on the same side and date of service will trigger a National Correct Coding Initiative (NCCI) edit. The same applies to conventional frontal and sphenoid procedures on that side. Examples are 31276 for frontal sinus exploration and 31287 or 31288 for sphenoidotomy.

Pairing 31298 with 31295 on the same side is allowed. Check the current CMS NCCI procedure-to-procedure edits before submitting claims with more than one sinus endoscopy code.

Billing CPT 31298 bilaterally: modifier 50 rules

CPT 31298 bilateral billing applies when the surgeon dilates the frontal and sphenoid ostia on both the left and right sides in the same session. The correct claim format depends on the payer.

• Medicare: bill one line of 31298 with modifier 50 and one unit. The CY2026 Physician Fee Schedule gives 31298 bilateral surgery indicator 1. Medicare therefore pays 150% of the single-side fee schedule amount, or the billed charge if that is lower.
• Commercial payers: some require two lines with RT and LT modifiers instead of one line with modifier 50. Verify payer-specific instructions before submission.
• Different sites on each side: modifier 50 applies only when the same code is performed on both sides. If the right side gets 31298 and the left side gets 31296 alone, bill each code with its own RT or LT modifier.
• Multiple procedures: 31298 carries multiple procedure indicator 3, the endoscopy family rule with 31231 as the base code. With another family code such as 31295, Medicare pays the highest-valued endoscopy in full and the next one minus the 31231 base value.
• Modifier 51: unrelated surgical procedures on the same day take the standard 50% multiple-procedure reduction. Append modifier 51 where the payer asks for it, and remember that the bilateral adjustment is applied first.

Always confirm the bilateral billing policy in the payer’s provider manual before claim submission. A wrong modifier format usually leads to a denial that a corrected claim can resolve without a formal appeal.

CPT code 31298 reimbursement: Medicare fee schedule and RVU values

The CMS Medicare Physician Fee Schedule publishes the allowed amounts for CPT 31298 each year. The values below come from the CY2026 relative value file (October release, RVU26D). Use the FastRVU lookup tool to apply the geographic adjustment for your locality.

Commercial payer rates are set by contract and often differ from Medicare. Practices using claims management software can post each ERA against its claim and compare expected and received payments per code. A 31298 payment below the contracted rate then shows up as soon as the remittance arrives.

CPT 31298 prior authorization: payer requirements and clinical criteria

Prior authorization for CPT 31298 depends on the payer. Many commercial plans and some state Medicaid programs require it for balloon sinus dilation, while traditional Medicare generally does not. Insurance eligibility verification should confirm the auth rule when the procedure is scheduled, not on the day of service.

• Medicare: traditional Medicare generally does not require prior authorization for 31298, but the record must still support medical necessity. Medicare Advantage plans set their own rules.
• Commercial plans: many require prior auth. Criteria typically include chronic rhinosinusitis lasting 12 weeks or more and failed conservative therapy, such as nasal corticosteroids, saline irrigation and antibiotics where appropriate. Many policies also ask for CT imaging confirming obstruction at each affected site.
• Medicaid: requirements vary by state. Some state programs publish coverage policies with specific criteria for balloon sinus ostial dilation. Check your state’s Medicaid fee schedule and coverage policy before submitting an auth request.
• Clinical documentation for auth: include the ICD-10 diagnosis codes, CT report, office notes documenting failed medical management, and the planned procedural approach.

Approvals are usually code-specific, so an approval for 31296 or 31297 alone may not cover 31298. Name each planned code on the prior authorization form, including 31295 when the maxillary ostium may also be dilated. If the operative plan changes and a different code becomes appropriate, reauthorize before proceeding where possible. Otherwise, document the intraoperative finding that changed the approach.

ICD-10 diagnosis codes that support CPT code 31298

Pairing 31298 with an ICD-10 diagnosis code that does not match the sinus sites in the operative report is a common claim error. Because 31298 covers the frontal and sphenoid ostia, the diagnoses on the claim should support disease at those two sites.

For 31298, the usual pairing is J32.1 with J32.3, or J32.8 or J32.4 where the documentation supports them. Avoid J32.9 when a site-specific code is supported by the clinical record. Some payer coverage policies treat it as insufficient to establish medical necessity for balloon dilation.

Documentation requirements for a CPT 31298 claim

Medical billing compliance for surgical sinus procedures requires a complete pre-operative and operative record. Submitting a clean claim begins with ensuring every required document exists before the procedure date, not after the denial arrives.

• CT sinus imaging: pre-operative CT of the paranasal sinuses documenting obstruction at the frontal and sphenoid ostia. Report date and findings must align with the surgical indication.
• Failed medical therapy: office notes showing courses of nasal corticosteroids, saline irrigation, and antibiotics where clinically appropriate. Many payer policies ask for at least 12 weeks of conservative management.
• Operative report: must name the side and each ostium dilated, describe the balloon catheter technique, and confirm placement at each ostium. For 31298, both the frontal and the sphenoid ostia must appear, with a post-dilation check of patency.
• Fluoroscopy documentation: if fluoroscopic guidance was used, document it. The code already includes fluoroscopy when performed, but an undocumented service is treated as not performed.
• Diagnosis-to-procedure linkage: each ICD-10-CM code on the claim must connect to the specific anatomic site treated. A diagnosis that does not match the site is a frequent denial reason for this code family.

Common denial reasons for CPT 31298 and how to prevent them

Each denial reason below traces back to a step that can be checked before the claim goes out. A structured denial management workflow builds those checks into scheduling, coding and submission. Check common denial codes in your ERA files to identify patterns specific to your payer mix.

How claims management software supports CPT 31298 billing

Coding errors on 31298 tend to begin in the operative note. A single-site note gets coded as the combination code, or a frontal and sphenoid case gets split into 31296 and 31297. Pabau keeps clinical notes, uploaded CT reports and treatment history on one patient record for the coder to check.

Once the coder has chosen the code, Pabau’s claims management pulls the data already on the record into a pre-filled claim. It then submits and tracks that claim through Claim.MD, our US clearinghouse integration, and posts the remittance when the ERA arrives.

Pabau does not select CPT codes or obtain authorizations. Your team keeps that decision, and Pabau keeps the finished claim moving and visible.

The result is fewer claims lost between the procedure room and the payer, and a denial list your team can sort by reason code.

Track every sinus dilation claim to payment

Pabau’s claims management submits and tracks ENT claims through Claim.MD and posts remittances, so your team can follow each 31298 claim from submission to payment.

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Conclusion

Code 31298 from the operative note, never from the surgical plan. A note naming both the frontal and sphenoid ostia on one side supports 31298, and a maxillary dilation on that side adds 31295. A note naming only one of them belongs to 31296 or 31297.

The rest of the payment risk sits upstream of coding. Confirm the payer’s auth rule and bilateral format at scheduling, and match every ICD-10 code to a sinus the note says was treated.

Pabau’s claims management tracks each sinus dilation claim through Claim.MD and posts the remittance against it, so a short payment surfaces early. To see that workflow on your own ENT claims, book a demo with the team.

Continue your research

Need to verify what your clearinghouse sends on an ENT claim? Understanding the 837 claims file explains the electronic transaction format used to transmit CPT and diagnosis code data to payers.

Getting denials with no clear reason code? Electronic remittance advice (ERA) explained breaks down how to read 835 remittance files and act on adjustment reason codes.

Want a structured approach to reducing balloon sinuplasty write-offs? Revenue cycle management for medical practices covers the end-to-end workflow from eligibility check to final payment posting.

Planning an auth request for a sinus procedure? The prior authorization process walks through each step from the payer check to the approval.

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