Crystal's MCW Coder Hub🏥 CPT Code 31255 — Nasal/Sinus Endoscopy, Surgical; with Ethmoidectomy, Total (Anterior and Posterior)
CPT Code Description
CPT 31255 describes a functional endoscopic sinus surgery (FESS) procedure in which the surgeon uses a rigid nasal endoscope — inserted transnasally through the natural nasal passages — to perform a total ethmoidectomy, removing diseased and obstructive tissue from both the anterior and posterior ethmoid sinuses. This is a surgical endoscopy, meaning tissue is actually excised; it is not merely a diagnostic look-around.
The ethmoid sinuses are a honeycomb-like labyrinth of small air cells nestled between the orbit (eye socket) and the nasal cavity, situated between the nose and the eyes. They are divided anatomically into two compartments: the anterior ethmoid cells, which drain into the middle meatus, and the posterior ethmoid cells, which drain into the superior meatus. When both compartments are diseased, a total ethmoidectomy (31255) is required rather than a partial anterior-only ethmoidectomy (31254).
During the total ethmoidectomy, the surgeon opens the ethmoid bulla, resects it with cutting forceps, clears anterior ethmoid cells including removal of the loose bony partitions from the lamina papyracea, then perforates the basal lamella of the middle turbinate to access the posterior ethmoid cells, excising diseased tissue, polyps, and bony septa in the posterior compartment. The lamina papyracea — the paper-thin bone separating the ethmoid sinus from the orbit — serves as a critical anatomical landmark throughout this dissection. Hemostasis is achieved, and nasal packing may be placed to reduce postoperative bleeding and support the mucosal architecture.
Note
This procedure is performed under general anesthesia in the vast majority of adult cases and may utilize image-guided stereotactic navigation (add-on code +61782).
ICD-10-PCS Crosswalk (Inpatient Facility)
For inpatient hospital billing, CPT codes are not used. The following ICD-10-PCS codes correspond to endoscopic ethmoid sinus excision:
| ICD-10-PCS Code | Description |
|---|---|
| 09BU8ZZ | Excision of Right Ethmoid Sinus, Via Natural or Artificial Opening Endoscopic |
| 09BV8ZZ | Excision of Left Ethmoid Sinus, Via Natural or Artificial Opening Endoscopic |
| 09BU8ZX | Excision of Right Ethmoid Sinus, Via Natural or Artificial Opening Endoscopic, Diagnostic |
| 09BV8ZX | Excision of Left Ethmoid Sinus, Via Natural or Artificial Opening Endoscopic, Diagnostic |
PCS Code Structure for 09BU8ZZ:
- Section 0 — Medical and Surgical
- Body System 9 — Ear, Nose, Sinus
- Root Operation B — Excision (cutting out or off, without replacement)
- Body Part U — Ethmoid Sinus, Right
- Approach 8 — Via Natural or Artificial Opening Endoscopic
- Device Z — No Device
- Qualifier Z — No Qualifier
Tip
For a bilateral total ethmoidectomy, both 09BU8ZZ (right) and 09BV8ZZ (left) would be reported. The diagnostic qualifier (X) is used when the excision is performed for biopsy/diagnostic purposes only. Standard therapeutic excisions use the Z qualifier.
ICD-10-CM Diagnosis Codes Commonly Linked
The following diagnosis codes represent the primary clinical indications for a total endoscopic ethmoidectomy. Medical necessity must be established through documentation of appropriate conservative treatment failure (typically 3-6 months of maximal medical therapy including topical corticosteroids, nasal saline irrigation, and antibiotics where appropriate).
| ICD-10-CM Code | Description | Notes |
|---|---|---|
| J32.2 | Chronic ethmoidal sinusitis | Most specific and preferred primary diagnosis for this procedure; indicates chronic inflammation of the ethmoid mucosa lasting 12+ weeks |
| J32.8 | Other chronic sinusitis (more than one sinus, not pansinusitis) | Use when multiple sinuses are involved but not all four sinus groups |
| J32.4 | Chronic pansinusitis | Use when all paranasal sinuses are involved bilaterally |
| J32.9 | Chronic sinusitis, unspecified | Least specific; use only when documentation does not identify specific sinuses |
| J33.0 | Polyp of nasal cavity | Nasal polyps in the nasal cavity proper; frequently co-occurs with ethmoid disease |
| J33.8 | Other polyp of sinus | Sinusoidal polyps (ethmoid polyps, antrochoanal polyps, etc.) |
| J33.9 | Nasal polyp, unspecified | Use when documentation does not specify location of polyp |
| J32.0 | Chronic maxillary sinusitis | Frequently co-coded when maxillary disease co-exists |
| J32.1 | Chronic frontal sinusitis | Co-coded when frontal involvement is documented |
| J01.20 | Acute ethmoidal sinusitis, unspecified | For acute presentations where surgical intervention is needed |
| J01.21 | Acute recurrent ethmoidal sinusitis | Recurrent acute disease that has failed conservative management |
J32.2 Description in Detail:
Chronic ethmoidal sinusitis represents a persistent inflammatory process of the ethmoid sinus mucosa lasting beyond 8-12 weeks that is caused by infections, allergies, anatomical factors, or the presence of nasal polyps. The ethmoid sinuses are frequently the nidus of sinus disease because of their central location and the fact that the maxillary, frontal, and sphenoid sinuses all drain through or near the ethmoid complex. Symptoms include nasal obstruction, mucopurulent rhinorrhea, facial pressure, anosmia/hyposmia, and postnasal drip. CT of the paranasal sinuses is the gold standard for imaging and should show mucosal thickening, air-fluid levels, or opacification of the ethmoid air cells to support medical necessity.
wRVU — Work Relative Value Units
| Metric | Value |
|---|---|
| Work RVU (wRVU) | 7.20 (CY 2025 MPFS) |
| Global Period | 090 days |
| Medicare Conversion Factor (2025) | $32.35 |
| Medicare Conversion Factor (2026, QP) | $33.57 |
| Medicare Conversion Factor (2026, non-QP) | $33.40 |
The wRVU of approximately 7.20 reflects the significant technical complexity of navigating the narrow nasal passages with an endoscope while carefully dissecting adjacent to the orbit, skull base, and optic nerve. The 90-day global period includes all routine follow-up care, postoperative nasal endoscopy, and debridements within 90 days of surgery — these are bundled and not separately billable by the operating surgeon during the global window (exceptions: unplanned return to OR, new/unrelated problems, modifier -24/-79 situations).
Comparing to the FESS code family, 31255 sits as a mid-value code: 31254 (partial/anterior only) carries lower wRVUs, while combination codes like 31253 (total ethmoidectomy + frontal exploration with tissue removal) carry higher wRVUs. This matters for billing sequence — always list the highest-wRVU procedure first on the claim.
Assistant Surgeon Payability
Yes — 31255 is generally assistant-payable, meaning a qualified assistant surgeon (PA, NP, or MD/DO assistant) may bill and receive reimbursement when assisting at a total ethmoidectomy, subject to payer-specific rules. Medicare allows assistant-at-surgery payment at 16% of the surgeon’s fee when the procedure meets criteria. However, many commercial payers restrict assistant billing. Always verify with the specific payer prior to billing assistant services. For Medicare, the assistant surgeon appends modifier -80 (or -AS for non-physician practitioners) to the claim.
Includes (Bundled Into 31255)
The following services are considered part of the 31255 global service and cannot be billed separately on the ipsilateral side:
- 31254 — Nasal/sinus endoscopy with partial (anterior) ethmoidectomy: the anterior ethmoidectomy is inherently performed as part of the total procedure; do not report 31254 with 31255 on the same side
- 31231 — Nasal endoscopy, diagnostic: the diagnostic endoscopic inspection is included in all surgical endoscopy codes
- Routine pre- and postoperative care within the 90-day global period
- Nasal packing placement and removal
- Hemostasis management during the procedure
- Image guidance when used as a routine part of the procedure (note: +61782 stereotactic navigation is separately reportable per NCCI edits as it represents additional physician work not included in 31255)
Excludes / Do Not Report Together (Ipsilateral)
Attention
Per CPT parenthetical instructions, do not report 31255 in conjunction with the following when performed on the same (ipsilateral) side:
- 31253 — Total ethmoidectomy + frontal exploration with tissue removal (this is the combination code that replaces 31255 + 31276)
- 31254 — Partial ethmoidectomy (bundled into 31255)
- 31257 — Total ethmoidectomy + sphenoidotomy (combination code replacing 31255 + 31287)
- 31259 — Total ethmoidectomy + sphenoidotomy with tissue removal (combination code replacing 31255 + 31288)
- 31276 — Frontal sinus exploration (when performed with total ethmoidectomy, use 31253 instead)
- 31287 — Sphenoidotomy (when performed with total ethmoidectomy, use 31257 instead)
- 31288 — Sphenoidotomy with tissue removal (when performed with total ethmoidectomy, use 31259 instead)
- 0406T / 0407T — Category III codes for balloon sinus dilation
Key bundling rule:
Codes 31253, 31257, and 31259 were introduced in 2018 specifically to replace the practice of billing 31255 + the sphenoid or frontal code separately. Using the combination codes on the ipsilateral side optimizes coding accuracy and represents the inclusive code per CPT guidelines. For bilateral procedures where different procedures are performed on each side, laterality modifiers (RT/LT or 50) and careful documentation are essential.
MS-DRG Assignment (Inpatient)
CPT 31255 is primarily an outpatient or ambulatory surgical center procedure. However, when performed in the inpatient setting, the ICD-10-PCS codes for ethmoidectomy (09BU8ZZ, 09BV8ZZ) are operating room procedures that affect MS-DRG assignment. All ethmoid sinus excisions fall under MDC 03 — Diseases and Disorders of the Ear, Nose, Mouth, and Throat.
When an ethmoidectomy is the operative procedure driving DRG assignment in an inpatient admission:
| MS-DRG | Description | Notes |
|---|---|---|
| 149 | Dysequilibrium | Not typical for ethmoidectomy |
| 150 | Epistaxis with MCC | Can result from post-sinus surgery complications |
| 151 | Epistaxis with CC | Same |
| 154 | Other Ear, Nose, Mouth and Throat Diagnoses with MCC | May apply when diagnosis-driven (e.g., abscess, invasive fungal sinusitis) |
| 155 | Other Ear, Nose, Mouth and Throat Diagnoses with CC | Same |
| 156 | Other Ear, Nose, Mouth and Throat Diagnoses without CC/MCC | Same |
Info
In practice, most ethmoidectomies are performed in an ambulatory surgery center (ASC) or hospital outpatient department (HOPD). Inpatient admission for a routine total ethmoidectomy is uncommon and may trigger medical necessity scrutiny. Inpatient coding is more likely when the ethmoidectomy is performed in the context of a complication (epistaxis, CSF leak, orbital complication), invasive fungal sinusitis, concurrent procedures (e.g., CSF leak repair, orbital decompression), or significant comorbidity burden requiring overnight monitoring. In those cases, the DRG will often be driven by the principal diagnosis rather than the procedure itself.
HCC (Hierarchical Condition Category)
Not applicable. CPT 31255 is a procedure code, not a diagnosis code. The underlying diagnoses that drive the need for a total ethmoidectomy (chronic sinusitis, nasal polyps) are not HCC-mapped diagnoses and do not carry HCC risk scores for Medicare Advantage capitation purposes. HCC coding considerations would arise only if the patient has significant comorbidities documented during the same encounter (e.g., COPD, diabetes, immunosuppression contributing to chronic sinusitis).
CPT Code Tree — FESS Family
Nasal Endoscopy
│
├── 31231 — Diagnostic, unilateral or bilateral (separate procedure)
│
├── 31237 — Surgical; with biopsy, polypectomy, or debridement
│
├── 31240 — Surgical; with concha bullosa resection
│
├── Ethmoidectomy
│ ├── 31254 — Partial (anterior only)
│ └── 31255 ★ — TOTAL (anterior and posterior)
│
├── Ethmoidectomy + Additional Sinus (Combination Codes — replace 31255 + individual codes)
│ ├── 31253 — Total ethmoidectomy + frontal sinus exploration with tissue removal
│ ├── 31257 — Total ethmoidectomy + sphenoidotomy
│ └── 31259 — Total ethmoidectomy + sphenoidotomy + tissue removal from sphenoid
│
├── Maxillary Antrostomy
│ ├── 31256 — Maxillary antrostomy only
│ └── 31267 — Maxillary antrostomy + tissue removal
│
├── Frontal Sinus
│ └── 31276 — Frontal sinus exploration with or without tissue removal
│ (Use 31253 instead when performed with total ethmoidectomy)
│
├── Sphenoid Sinus
│ ├── 31287 — Sphenoidotomy
│ │ (Use 31257 instead when performed with total ethmoidectomy)
│ └── 31288 — Sphenoidotomy with tissue removal
│ (Use 31259 instead when performed with total ethmoidectomy)
│
└── Balloon Sinus Dilation (BSD)
├── 31295 — Maxillary ostium dilation
├── 31296 — Frontal sinus ostium dilation
├── 31297 — Sphenoid ostium dilation
└── 31298 — Frontal and sphenoid ostia dilation
Hint
Common Modifier Usage
| Modifier | Use Case |
|---|---|
| -50 | Bilateral procedure — ethmoidectomy performed on both sides during same operative session |
| -RT / -LT | Right or left side designation — alternative to -50 when procedures differ by side |
| -51 | Multiple procedures — secondary procedures listed with -51 (e.g., 31255 listed first, 31256-51 for maxillary antrostomy) |
| -59 / -XS | Distinct procedural service — used when billing codes that may appear bundled but were performed as separate, distinct services |
| -80 / -AS | Assistant surgeon / assistant at surgery by non-physician practitioner |
| -22 | Increased procedural services — documented unusual complexity (extensive scarring, revision case, invasive fungal) |
| -78 | Unplanned return to OR — complications requiring return to operating room during global period |
| -79 | Unrelated procedure during global period |
Coding Examples
Example 1 — Straightforward Bilateral Total Ethmoidectomy A patient with refractory bilateral chronic ethmoidal sinusitis (J32.2) undergoes bilateral total ethmoidectomy endoscopically. Both anterior and posterior ethmoid cells are removed on each side. CPT: 31255-50 (bilateral modifier applied; reimbursement at 150% of the single-unit fee) ICD-10-CM: J32.2
Example 2 — Unilateral Total Ethmoidectomy with Maxillary Antrostomy and Tissue Removal Right-sided total ethmoidectomy with right maxillary antrostomy and removal of antral polypoid mucosa. CPT (in wRVU order): 31255-RT, 31267-RT-51 ICD-10-CM: J32.2, J32.0
Example 3 — Total Ethmoidectomy + Sphenoidotomy with Tissue Removal (Same Side) Left total ethmoidectomy and left sphenoidotomy with removal of inspissated secretions from the sphenoid sinus. Use the combination code rather than unbundled codes. CPT: 31259-LT Note: Do NOT report 31255-LT and 31288-LT separately. 31259 is the correct combination code. ICD-10-CM: J32.2, J32.3
Example 4 — Total Ethmoidectomy + Frontal Exploration with Tissue Removal Bilateral total ethmoidectomy and bilateral frontal sinus exploration with removal of polyps from frontal recesses. CPT: 31253-50 Note: 31253 replaces the combination of 31255 + 31276 on the ipsilateral side. ICD-10-CM: J32.2, J32.1, J33.8
Example 5 — Complex Bilateral Case: Different Procedures Each Side Right side: total ethmoidectomy, sphenoidotomy with tissue removal (= 31259-RT) Left side: total ethmoidectomy, frontal exploration with tissue removal, sphenoidotomy with tissue removal Left side breakdown: 31253 covers ethmoidectomy + frontal; add 31288 for left sphenoidotomy with tissue removal CPT (in wRVU order): 31259-RT, 31253-LT, 31288-LT-51 ICD-10-CM: J32.8 (bilateral multi-sinus), J33.8
Example 6 — Inpatient Scenario with Invasive Fungal Sinusitis Patient with AML on chemotherapy admitted for invasive Aspergillus sinusitis requiring emergent surgical debridement including total ethmoidectomy. ICD-10-CM: B44.1 (other pulmonary aspergillosis — use appropriate aspergillosis code), J32.2, underlying malignancy code ICD-10-PCS: 09BU8ZZ, 09BV8ZZ (plus additional sinus debridement codes as appropriate) MS-DRG: Likely driven by fungal infection/malignancy with applicable CC/MCC weight
Documentation Requirements
For CPT 31255 to be supported, the operative report must explicitly document:
- Use of the nasal endoscope (confirms endoscopic approach rather than open/intranasal)
- Entry into and removal of tissue from the anterior ethmoid sinus (ethmoid bulla removal, clearance of anterior cells)
- Perforation of the basal lamella and entry into the posterior ethmoid sinus with removal of diseased tissue
- Identification of key anatomical landmarks (lamina papyracea, skull base, basal lamella)
- The side(s) operated on (right, left, or bilateral)
- Final pathology submitted (when applicable)
If documentation only describes anterior work without explicit perforation of the basal lamella and posterior cell work, the encounter downcodes to 31254 (partial/anterior). Query the surgeon before assuming total ethmoidectomy without clear posterior documentation.
Key Coding Pitfalls
Pitfall 1 — Unbundling 31255 + 31276 or 31287/31288 on the same side. Since 2018, combination codes (31253, 31257, 31259) replaced these combinations. Billing 31255 and 31276 together on the ipsilateral side is incorrect; the correct code is 31253.
Pitfall 2 — Billing 31254 and 31255 together. A total ethmoidectomy includes the anterior (partial) work. Bill only 31255 when both anterior and posterior compartments are addressed.
Pitfall 3 — Forgetting modifier -50 for bilateral. If not caught, bilateral procedures may be underpaid as unilateral.
Pitfall 4 — Mistaking “frontal recess exploration” for 31276. If the surgeon only looks up toward the frontal sinus but does not enter and work within the frontal sinus proper (sinusotomy), this work is considered part of 31255 and 31276 should not be added. Documentation of “frontal sinuses patent” alone does not support 31276.
Pitfall 5 — Suctioning mucus/pus only. If the procedure consists only of suctioning purulent material without tissue excision or debridement of necrotic tissue, the appropriate code is 31231 (diagnostic endoscopy) or 31237 (with debridement), not 31255.