In nasal endoscopy billing 31231 rarely stands alone when a laryngoscopy happens the same day. NCCI treats diagnostic nasal endoscopy as part of flexible laryngoscopy (31575) and laryngoscopy with stroboscopy (31579).
So when one flexible scope passes through the nose to the larynx, only the laryngoscopy code is billed. CPT 31231 is added with modifier 59 or XS only when a separate rigid scope was medically necessary and the note explains why.
31575 and 31579 are never billed together, since stroboscopy already includes the basic laryngeal exam. The sections below show how each pairing works and what keeps it payable.
Why 31231 Bundles Into Other Scopes
CPT 31231 diagnostic nasal endoscopy is defined as unilateral or bilateral, and it is a separate procedure. Those two words shape every same-day billing decision.
- One unit covers both sides. Do not add modifier 50, RT or LT.
- It is a component code. It folds into surgical sinus endoscopy and laryngoscopy codes done the same day.
- It includes the full nasal exam. That means the nasal cavity, middle and superior meatus, turbinates and sphenoethmoidal recess.
The rigid vs flexible endoscope choice matters too. A rigid telescope gives a sharper view of the middle meatus and sinus openings, while a flexible scope can travel on to the throat.
That difference is the core of the same-day question. The AAO-HNS CPT resources cover it in more detail.
How the 31231 and 31575 Pair Edit Works
31575 flexible laryngoscopy passes through the nose, so NCCI bundles 31231 into it as a component. The NCCI edit 31231 31575 allows a modifier override, but only for a real reason. CMS kept that override in 2008 after the Academy objected to removing it, as explained in the AAO-HNS same-date guidance.
The resulting rule for nasal endoscopy billing 31231 is clear. If one flexible scope examined both the nose and larynx, bill 31575 alone. The same logic applies to flexible laryngoscopy codes 31576 through 31578.
When a Second Scope Earns Its Own Line
The override exists for a narrow case: a separate rigid endoscope that was medically reasonable and necessary. These five points decide whether a claim fits.
A Rigid View the Flexible Scope Could Not Give
Sometimes anatomy blocks the flexible scope from showing the middle meatus or sinus openings. A rigid telescope then adds information the laryngoscopy could not, which supports both codes.
Two Complaints, Two Exams
A patient seen for chronic sinus symptoms and new hoarseness has two separate problems. Each scope answers a different clinical question, and the diagnosis pointers should show that.
Picking 59 or XS
Modifier 59 marks a distinct service, while XS points to a separate organ or structure. CMS guidance on 59 and X modifiers favors the more specific X modifier when it fits, so check which one each payer prefers.
Keeping the Pairing Rare
The Academy itself advises using this combination infrequently. A provider who bills both scopes on most laryngoscopy visits will stand out in payer data.
Cases That Do Not Qualify
A longer look at the nose with the same flexible scope does not count. Neither does switching scopes for convenience or habit when one instrument could have done both exams.
Same-Day Scope Combinations at a Glance
Most scope-to-scope questions fall into a few patterns. This table shows how each one is usually coded for Medicare and payers that follow NCCI.
| Same-day encounter | Bill | Why |
|---|---|---|
| One flexible scope, nose to larynx | 31575 | 31231 is included |
| Flexible laryngoscopy plus needed rigid nasal scope | 31575 + 31231-59 or XS | Separate scope documented |
| Stroboscopy with one flexible scope | 31579 | Nasal view included |
| Stroboscopy plus needed rigid nasal scope | 31579 + 31231-59 or XS | Separate scope documented |
| Flexible laryngoscopy and stroboscopy | 31579 only | 31575 is included |
Rules can differ for commercial plans that do not follow NCCI. Clean, consistent coding on these combinations is one reason ENT teams see results like those in this first-pass acceptance case study.
Pairing 31231 With Stroboscopy
31579 videostroboscopy is a flexible or rigid laryngoscopy that captures vocal fold vibration. 31231 bundles into 31579 just as it does with 31575, so a flexible stroboscope passed through the nose leaves no separate nasal service.
A rigid transoral telescope never enters the nose. A nasal exam then needs its own instrument and reason, and 31231 with 59 or XS can apply. Never add 31575 to 31579 on the same visit, since stroboscopy replaces the basic exam.
In nasal endoscopy billing 31231 with stroboscopy works only when the note names both scopes, the nasal complaint and each set of findings.
Diagnostic Look or Postoperative Cleanout?
31237 debridement is a surgical endoscopy that includes the diagnostic exam, so 31231 is not billed with it on the same visit. After surgery, the global period matters. Endoscopic sinus codes have a zero-day Medicare global, but a same-session septoplasty carries 90 days, and the longest global governs later scopes.
Moda Health policy RPM009 is a useful example. When a 10- or 90-day global applies, it treats 31231 and 31237 as related, pays them only with modifier 58 for staged care, and rejects modifier 79.
The staging plan must appear in the original op note or H&P, or the debridement folds into the surgical payment. Related surgical traps are covered in our post on FESS billing errors.
When the Visit Itself Is Billable Too
Endoscopy codes already include the brief evaluation that leads to the scope. A separate office visit pays only when it goes beyond that decision.
Nasal endoscopy with E/M modifier 25 fits when the provider also manages another problem or does a full workup for a new complaint. Simply deciding to scope does not qualify. Our guide to modifier 25 for ENT covers the documentation that keeps both services payable.
Diagnoses and Notes That Support Two Scopes
Nasal endoscopy medical necessity rests on the diagnosis and the note together. These five habits keep both codes defensible.
A Different Diagnosis Behind Each Code
Link 31231 to a nasal or sinus problem, such as J32.0 chronic maxillary sinusitis, J33.0 nasal polyp or R04.0 epistaxis. Link the laryngoscopy to a voice or airway problem, such as R49.0 dysphonia or a J38 vocal cord code.
The Instrument Named for Each Exam
State “rigid 0-degree telescope” for the nasal exam and “flexible laryngoscope” or “rigid stroboscope” for the larynx. Without that detail, an auditor will assume one scope did both.
Findings Recorded by Area
Describe the nasal findings and the laryngeal findings in separate paragraphs. This shows two exams took place rather than one long pass.
Stroboscopy Specifics
For 31579, note the mucosal wave, symmetry, amplitude and closure pattern. These details separate a true stroboscopy from a standard look at the vocal folds.
A One-Line Reason for the Second Scope
A short statement, such as “flexible view of the middle meatus limited by septal deviation,” justifies the extra instrument. Regular ENT billing audits can confirm these notes match nasal endoscopy billing 31231 claims before payers ask.
Same-Day Scope Visits That Serve Patients and Satisfy Payers
For patients, seeing the nose and throat in one visit means faster answers and fewer trips. For the revenue cycle, it means one rule to apply every time. The laryngoscopy code comes first. Nasal endoscopy billing 31231 joins it only when a second, rigid scope answered a separate question and the note proves it.
Applied consistently, that rule keeps same-day scopes paid without inviting audits. When those claims need closer review, dedicated ENT billing services from MBW RCM can support the coding and documentation checks.
Nasal Endoscopy Billing 31231 FAQs
Can 31231 be billed with modifier 50?
No. CPT 31231 is defined as unilateral or bilateral, so one unit covers both sides of the nose.
Can 31575 and 31579 be billed on the same day?
No. Stroboscopy includes the basic laryngeal exam, so report 31579 alone when both are performed.
Is modifier XS better than 59 for a second scope?
CMS prefers the more specific X modifiers when one fits. XS describes a separate structure, but some payers still ask for 59, so follow each payer’s rules.
Can 31231 be billed during a surgical global period?
It depends on the payer and the global attached to the surgery. Some plans pay it only with modifier 58 when the follow-up scope was planned and documented.
What diagnosis supports 31231 with a laryngoscopy?
In nasal endoscopy billing 31231 needs its own nasal or sinus diagnosis, such as chronic sinusitis or polyps. The laryngoscopy should point to a separate voice or airway diagnosis.