Documenting CPT 31231 Nasal Endoscopy with Same-Day Modifier 25 E/M: The 2026 Operations Playbook

Documenting CPT 31231 with a same-day Modifier 25 E/M requires a significant, separately identifiable evaluation that supports its own medical decision making, a distinct procedure note listing every structure visualized, and clear evidence that the E/M went beyond the routine preprocedure assessment bundled into the zero-day global.

This playbook is for outpatient otolaryngologists, rhinologists, allergists, and advanced practice clinicians who perform diagnostic nasal endoscopy during office visits. It covers the documentation architecture, coding rules, audit triggers, and capture workflow needed to defend both line items. For related procedure guidance, see the Specialty Clinical Documentation Library.

CPT 31231 carries a zero-day global that bundles the preprocedure evaluation

CPT 31231 describes diagnostic nasal endoscopy, unilateral or bilateral, and is designated a "separate procedure." Under the Medicare Physician Fee Schedule it has a 000 global period. Payment for the code includes the brief history, the focused examination, and the decision to perform the endoscopy on the same day.

The National Correct Coding Initiative (NCCI) Policy Manual states that the decision to perform a minor surgical procedure is included in that procedure's payment and should not be reported as a separate E/M. A visit note that only states "nasal obstruction, endoscopy performed" therefore supports 31231 alone. Adding 99213-25 to that note is a common source of recoupment.

Because the global is zero days, there are no bundled postoperative visits. A follow-up visit on a later date is billed on its own merits. The Modifier 25 question applies only to the E/M performed on the same date of service as the endoscopy.

Bilateral examination does not change the unit count

The code descriptor already includes both nasal cavities. Report one unit of 31231 whether you examine one side or both. Do not append modifier 50, and do not split the service into RT and LT lines. Record which sides were examined, and why, inside the procedure note so a reviewer can confirm the clinical scope.

Modifier 25 requires an E/M that stands alone without the endoscopy

Modifier 25 signals a significant, separately identifiable E/M service performed by the same physician on the same day as a procedure. CPT and CMS both state that a different diagnosis is not required. What is required is work that exceeds the usual preprocedure and postprocedure care tied to 31231.

Apply the remove-the-procedure test

Auditors routinely use a subtraction method. They remove every sentence that relates to the decision to scope, the scope findings, and the consent discussion. If the remaining text still supports a billable E/M level by medical decision making (MDM) or time, Modifier 25 holds. If the remainder is thin, the E/M is denied or downcoded.

Elements that survive the subtraction typically include:

• Management of a chronic condition, such as adjusting intranasal corticosteroids, starting saline irrigation with budesonide, or reviewing biologic eligibility.

• Evaluation of a second problem, such as new dysphonia, otalgia, eustachian tube dysfunction, or allergic symptoms.

• Independent review of imaging, such as a prior sinus CT, with documented interpretation and a decision about repeat imaging.

• Prescription drug management with a named drug, dose, duration, and risk discussion (for example, an oral steroid taper in a patient with diabetes).

• Surgical candidacy discussion for functional endoscopic sinus surgery after failed maximal medical therapy, including risks and alternatives.

The decision to scope is never the billable E/M

Statements like "endoscopy indicated to evaluate obstruction" belong to the procedure. They support medical necessity for 31231 but contribute nothing to the E/M level. Keep them in the procedure section or in a clearly labeled indication line, not in the E/M assessment where they inflate apparent MDM.

Chronic rhinosinusitis diagnosis depends on symptoms plus objective endoscopic evidence

The AAO-HNS adult sinusitis guideline defines chronic rhinosinusitis (CRS) as 12 weeks or longer of two or more cardinal symptoms: mucopurulent drainage, nasal obstruction, facial pain, pressure, or fullness, and decreased sense of smell. The diagnosis also requires objective inflammation on endoscopy, CT, or anterior rhinoscopy.

This definition makes 31231 clinically central, and it also creates a documentation trap. When the endoscopy is the objective confirmation, the E/M must still capture the symptom chronology, duration, prior treatments, and treatment response. Those history and management elements are what the E/M bills for. The endoscopic confirmation itself belongs to 31231.

Code to the highest specificity the findings support. Use J32.9 (ICD-10-CM) for chronic sinusitis, unspecified, only when sinus involvement cannot be localized. When endoscopy shows middle meatal purulence draining from a specific sinus, or CT localizes disease, use the site-specific J32 subcodes. Use J33 codes when polyps are visualized.

Failed maximal medical therapy must be quantified

Payers reviewing later surgical authorization look back at office notes. Record the specific medications, doses, durations, and adherence: for example, "fluticasone 50 mcg two sprays each nostril daily for 14 weeks, saline irrigation twice daily for 12 weeks, amoxicillin-clavulanate 875 mg twice daily for 21 days, persistent obstruction and hyposmia." This history supports E/M MDM and future surgical necessity.

A compliant 31231 procedure note names every structure examined

The procedure note must stand as a separate, complete document. Auditors expect the following elements, written so the procedure could be reviewed with no reference to the E/M:

• Indication and laterality: the specific symptom or finding prompting endoscopy and the sides examined.

• Consent: verbal or written consent, risks discussed (epistaxis, discomfort, vasovagal response).

• Topical preparation: decongestant and anesthetic agent, such as oxymetazoline with 4% lidocaine.

• Instrument: rigid (0 or 30 degree) or flexible endoscope.

• Structures visualized: septum, inferior and middle turbinates, middle meatus, superior meatus and sphenoethmoidal recess where visible, and nasopharynx including eustachian tube orifices.

• Findings by side: edema, purulence, polyps (with a grading scale), crusting, masses, or normal mucosa.

• Tolerance and complications: patient tolerance, bleeding, and any intervention required.

Use a validated grading tool when possible. The Lund-Kennedy endoscopic score (polyps, edema, discharge, scarring, crusting per side) gives auditors and future reviewers a numeric baseline. It also converts a subjective finding into trendable data that supports later medical or surgical decisions.

Avoid cloned normal findings

Templated "all structures normal" text that repeats identically across visits draws scrutiny. Findings should reflect what was actually seen on that date. Specialty macros help with structure but must be edited for each patient. The 1,000+ Specialty Clinical Macros library provides structure-level fields that require active completion instead of default normals.

Separate documentation fields defend each billing element under audit

The table below maps each clinical parameter to its documentation requirement, the typical audit vulnerability, and the capture mechanism used in the Scribing.io Clinical Interface.

Separate diagnoses strengthen Modifier 25 but are not mandatory

A second, unrelated problem is the clearest support for Modifier 25. Consider a patient returning for CRS follow-up who also reports four weeks of hoarseness. Evaluating that complaint, linking it to R49.0 (ICD-10-CM) for dysphonia, reviewing voice use, reflux symptoms, and smoking history, and planning further evaluation is independent E/M work.

Link diagnoses to the correct claim lines. The E/M line carries both J32.x and R49.0 when both were addressed. The 31231 line carries the diagnosis that justified the nasal endoscopy. Pointer errors, such as linking R49.0 to 31231 when the nasal exam was for CRS, create a medical necessity mismatch on review.

Same-diagnosis Modifier 25 claims remain valid when the management work is real. A patient with uncontrolled CRS who needs a steroid taper decision, CT ordering, and a surgical counseling discussion has a moderate MDM E/M that exists regardless of the scope. Document that work in the E/M assessment and plan with specific reasoning.

Sample assessment and plan structure

Problem 1, chronic rhinosinusitis without polyps, uncontrolled: 16 weeks of obstruction and hyposmia despite 14 weeks of intranasal steroid and irrigation. Reviewed prior CT (outside facility) independently. Starting oral prednisone taper, discussed hyperglycemia risk given type 2 diabetes. Repeat CT in 6 weeks. Discussed endoscopic sinus surgery as an option if refractory.

Problem 2, dysphonia, new: 4 weeks of hoarseness, 20 pack-year smoking history, no dysphagia. Plan flexible laryngoscopy at this or next visit based on findings, reflux counseling, smoking cessation discussion. The nasal endoscopy is then documented in its own note below these problems.

Time-based E/M leveling must exclude all endoscopy minutes

Since the 2021 office E/M revision, total time on the date of service may determine the level. CPT excludes time spent on separately reported services. For 31231, that includes scope preparation, topical decongestion and anesthesia wait time, the endoscopy, and the procedure note.

Time attestations that read "45 minutes total" without excluding procedure time are a frequent audit finding. Write the statement explicitly: "Total E/M time 32 minutes, excluding time for the separately reported nasal endoscopy." When procedure work dominates the visit, MDM-based leveling is usually more defensible than time.

G2211 is not payable with a procedure-linked Modifier 25 E/M in 2026

The G2211 visit complexity add-on recognizes longitudinal care relationships. CMS policy allows G2211 with a Modifier 25 E/M only when the same-day service is an annual wellness visit, vaccine administration, or a Medicare Part B preventive service. A diagnostic procedure such as 31231 does not qualify.

Many specialty practices manage CRS longitudinally and may reasonably bill G2211 on non-procedure visits. On endoscopy days, suppress the add-on. Build this as a hard rule in charge capture rather than relying on manual coder review, because the error repeats across every procedure encounter and compounds into a pattern finding.

NCCI edits govern 31231 alongside other same-session codes

Diagnostic endoscopy is included in surgical endoscopy on the same side. When a polyp biopsy or postoperative debridement is performed (31237), the diagnostic 31231 is not separately reported for that side. The "separate procedure" designation means 31231 is bundled when performed as part of a more comprehensive service through the same approach.

Laryngoscopy creates a common pairing question. NCCI pairs flexible laryngoscopy (31575) and 31231. Separate reporting requires distinct indications, a separate examination of distinct anatomy, and an appropriate NCCI-associated modifier (59 or XS where applicable) when the edit allows it. Document each indication and each set of findings independently.

Endoscopy within a sinus surgery global period needs separate modifier analysis. Routine postoperative examinations after a 90-day global procedure are included. Unrelated, staged, or complication-driven procedures follow different modifier rules (79, 58, or 78) and payer-specific policies, so verify before billing.

The same logic applies across procedural specialties

Separately identifiable documentation is a universal principle. Wound care clinics face an identical bundling test when billing E/M with debridement, which is covered in Wound Care Tissue Debridement Automation. The structural fix in both settings is a clean split between evaluation work and procedural work.

Payer algorithm review raises the bar for explicit documentation

Commercial and Medicare Advantage payers increasingly apply automated edits to Modifier 25 claims, and some have announced reductions in E/M payment when Modifier 25 is appended. Notes that rely on implied reasoning are vulnerable because automated systems and their human reviewers read only what is written.

California SB 1120, the Physicians Make Decisions Act, requires that medical necessity determinations involving artificial intelligence be made by a licensed clinician who reviews the individual record. That protection only helps when the record is explicit. A reviewing physician must be able to see the separate E/M work and the complete procedure on the page.

Audit-ready workflow: a five-step clinic protocol

Standardize the encounter sequence so documentation follows clinical reality. The following protocol works for most outpatient rhinology workflows:

1. Complete the E/M first: history, symptom duration, medication response, second problems, and the management plan for each.

2. State the procedure indication separately, naming the clinical question the endoscopy will answer.

3. Perform and narrate the endoscopy, naming each structure and finding by side as you examine it.

4. Write the procedure note as a standalone block with consent, agents, instrument, structures, findings, and tolerance.

5. Run a pre-claim check: remove-the-procedure test, diagnosis pointers, no modifier 50, no G2211, and time exclusion statement.

Conduct quarterly internal audits on a sample of Modifier 25 encounters. Track the percentage of E/M notes that pass the subtraction test, the rate of cloned endoscopy findings, and diagnosis pointer accuracy. A practice whose Modifier 25 rate sits far above specialty peers should expect payer outreach and should hold strong documentation in reserve.

Ambient AI documentation separates E/M and procedure content at capture

Most Modifier 25 failures originate at the moment of documentation, not at coding. Physicians naturally mix evaluation, indication, and findings in one narrative. An ambient scribe that classifies spoken content into E/M history, assessment, procedure indication, and procedure findings removes the reorganization burden from the physician.

The Scribing.io platform structures conversation into problem-oriented E/M sections and a separate procedure note. It prompts for missing structures, side-specific findings, symptom duration, and medication details, then flags coding conflicts such as modifier 50 on 31231 or G2211 alongside a procedure. The physician reviews and signs a note that already passes the subtraction test.

Clinical judgment remains with the physician. The system surfaces gaps and conflicts; it does not invent findings or choose E/M levels without clinician confirmation. That division of labor keeps the record accurate and defensible while reducing after-hours charting.

Frequently asked questions about documenting CPT 31231 with Modifier 25

Does CPT 31231 have a global period that affects same-day E/M billing?

Yes. CPT 31231 carries a zero-day global period under the Medicare Physician Fee Schedule, so the routine evaluation preceding the endoscopy is bundled. A same-day E/M is payable only with Modifier 25 when documentation proves a significant, separately identifiable service beyond the decision to scope.

Can Modifier 25 apply when both services share a J32.9 diagnosis?

Yes. CPT and CMS guidance state that a different diagnosis is not required for Modifier 25. The E/M must still contain independent work, such as medication management, imaging decisions, or assessment of additional symptoms, that exceeds the evaluation inherent to performing a diagnostic nasal endoscopy.

Should I append modifier 50 or RT/LT to CPT 31231?

No. The CPT 31231 descriptor reads unilateral or bilateral, so a single unit covers examination of one or both nasal cavities. Appending modifier 50 creates an overpayment risk and frequently triggers denials. Document which sides were examined and why inside the procedure note instead.

Is G2211 payable on a Modifier 25 E/M with nasal endoscopy?

No. CMS permits G2211 with a Modifier 25 E/M only when the other same-day service is an annual wellness visit, vaccine administration, or Medicare Part B preventive service. A diagnostic procedure such as CPT 31231 makes the add-on code non-payable, so suppress G2211 on these encounters.

Can endoscopy time count toward a time-based E/M level?

No. CPT instructs that time spent performing separately reported services, including scope preparation, topical decongestion, the endoscopy itself, and procedure note dictation, is excluded from E/M time. Document E/M minutes separately, and consider MDM-based leveling when procedure work dominates the visit.