👃 CPT 31290 — Nasal/Sinus Endoscopy, Surgical, With Repair Of Cerebrospinal Fluid Leak; Ethmoid Region
Quick Reference
wRVU: 18.14 | Global Period: 010 | Assistant Payable: No, under usual Medicare assistant-at-surgery payment rules | Bilateral Indicator: 1 Rule: CPT 31290 reports an endoscopic surgical repair of a CSF leak specifically in the ethmoid region. Medicare assigns a 10-day global period. The bilateral indicator of 1 means bilateral-payment adjustment may apply when medically necessary and properly reported; do not automatically assume a unilateral or bilateral claim is appropriate without operative-report support.1
📋 Clinical Description
CPT 31290 describes surgical nasal/sinus endoscopy with repair of a cerebrospinal fluid leak in the ethmoid region. The surgeon accesses the leak through the nasal cavity, identifies the ethmoid-region defect, and performs closure using the technique documented in the operative report, which may include graft material or local tissue. The report must support an actual CSF-leak repair rather than diagnostic examination, routine sinus surgery, or simple postoperative debridement. In contrast, 31231 is diagnostic nasal endoscopy and does not include surgical leak repair, while 31291 is reserved for a CSF-leak repair in the sphenoid region.2
The CPT code is anatomically specific to the ethmoid region, so code selection depends on the documented leak site rather than the endoscopic route alone. Do not report 31290 merely because the surgeon performed ethmoid surgery and encountered skull-base anatomy; documentation must establish repair of a CSF leak. When the principal service is a frontal sinus exploration, maxillary antrostomy, sphenoidotomy, or ethmoidectomy without repair of a CSF leak, select the separately applicable sinus endoscopy code instead. If extensive endoscopic skull-base tumor work exceeds the work described by an existing CPT code, an unlisted accessory-sinus service may require consideration rather than automatically adding unrelated sinus codes.2
This procedure may be performed in the following clinical contexts:
- Spontaneous anterior skull-base CSF leak — The surgeon confirms a cranial CSF leak involving the ethmoid region and performs endoscopic closure. Documentation should identify the leak site, etiology when known, and repair method.
- Postoperative CSF rhinorrhea — A patient develops a cranial CSF leak after prior sinonasal or skull-base surgery. The operative report must distinguish a true repaired leak from routine postoperative care or debridement.
- Traumatic ethmoid-region skull-base defect — Facial or skull-base trauma may create a defect with CSF rhinorrhea. Code the documented injury and the specific CSF-leak diagnosis in addition to the procedure when supported.
- Encephalocele-associated defect — An anterior skull-base encephalocele may be associated with a CSF leak requiring endoscopic repair. The record should identify whether the surgeon repaired only the leak or also performed separately reportable work.
🔬 Anatomical & Procedural Considerations
| Variant | Mechanism | Key Notes |
|---|---|---|
| Ethmoid-region CSF leak | CSF escapes through a defect involving the ethmoid region and adjacent anterior skull base, commonly presenting as CSF rhinorrhea. The surgeon uses a nasal/sinus endoscope to localize and repair the defect. | This is the anatomic circumstance represented by 31290. The record should clearly state ethmoid-region location and actual repair of the CSF leak. |
| Sphenoid-region CSF leak | CSF escapes through a defect involving the sphenoid region or adjacent skull base. Endoscopic access may still occur through the nasal cavity. | Report 31291, not 31290, when the documented repair is in the sphenoid region. Do not select the code based only on the surgical approach. |
| Bilateral ethmoid-region disease or defects | The procedure may involve work on both sides when separately documented as medically necessary. The bilateral payment indicator recognizes that bilateral adjustment may apply. | The operative report must establish the laterality and distinct work performed. Follow payer-specific bilateral-claim instructions and do not append -50 when the payer directs another reporting method. |
Clinical Pearl
The central coding issue is not whether an endoscope was used; it is whether the surgeon repaired a documented CSF leak in the ethmoid region. The procedure note should identify the leak location, method of closure, any graft or flap used, and whether the repair was unilateral or bilateral. A vague statement such as “skull-base repair” without location and leak documentation creates a high audit risk. 2
✅ Procedure Includes
- Surgical nasal/sinus endoscopic access necessary to reach and repair the documented ethmoid-region CSF leak.
- Identification and closure of the CSF-leak defect in the ethmoid region as described by the CPT service.
- Intraoperative work integral to completing the endoscopic repair, including routine inspection and hemostasis.
- The standard postoperative care included in the 10-day global surgical package, unless a separately reportable service meets modifier and documentation requirements.
❌ Excludes / Do Not Report Together
| Code | Description | Relationship |
|---|---|---|
| 31231 | Nasal endoscopy, diagnostic, unilateral or bilateral | Do not separately report diagnostic nasal endoscopy when it is integral to the same operative session and the surgical repair reported by 31290. A separately reportable diagnostic service would require distinct circumstances and documentation. |
| 31291 | Nasal/sinus endoscopy, surgical, with repair of cerebrospinal fluid leak; sphenoid region | Choose the code that matches the documented repair site. Do not report both codes solely because the surgeon used a transnasal approach or inspected both regions. |
| 31237 | Nasal/sinus endoscopy, surgical; with biopsy, polypectomy or debridement | Routine debridement, inspection, and work integral to CSF-leak repair are not separately reportable. A separately performed service requires documentation of a distinct indication, site, and work when allowed by NCCI and payer rules. |
| 31276 | Nasal/sinus endoscopy, surgical, with frontal sinus exploration, including removal of tissue from frontal sinus, when performed | Frontal sinus exploration is not automatically separately billable with 31290. Report it only when it is independently performed, medically necessary, not integral to the leak repair, and permitted under current payer edits. |
| 31299 | Unlisted procedure, accessory sinuses | Do not report an unlisted accessory-sinus code for the routine work already described by 31290. Consider 31299 only when a distinct service is not represented by an existing CPT code and the operative report supports the additional work. |
Bundling Alert
CPT 31290 has a 10-day global period, so routine postoperative visits and standard follow-up care are included. Report -24 only for an unrelated E/M service during the global period, and report -25 only when a significant, separately identifiable E/M service is performed on the same day as the procedure. Use -59 only when documentation supports a truly distinct procedural service and no more specific modifier is available; it must not be used to bypass an edit for integral endoscopic work. 1
🌳 Code Tree — Surgery: Endoscopy Procedures On The Accessory Sinuses
CPT 31231-31299 Surgery: Endoscopy Procedures on the Accessory Sinuses
│
├── 31231 Nasal endoscopy, diagnostic, unilateral or bilateral
│
├── 31233-31276 Nasal/sinus endoscopy, surgical
│ ├── 31267 Nasal/sinus endoscopy, surgical, with maxillary antrostomy; with removal of tissue from maxillary sinus (Global: 000)
│ ├── 31276 Nasal/sinus endoscopy, surgical, with frontal sinus exploration, including removal of tissue from frontal sinus, when performed (Global: 000)
│ ├── ▶▶ 31290 ◀◀ Nasal/sinus endoscopy, surgical, with repair of cerebrospinal fluid leak; ethmoid region ← YOU ARE HERE (Global: 010)
│ ├── 31291 Nasal/sinus endoscopy, surgical, with repair of cerebrospinal fluid leak; sphenoid region (Global: 010)
│ └── 31292 Nasal/sinus endoscopy, surgical; with medial orbital wall decompression (Global: 010)
│
└── 31299 Unlisted procedure, accessory sinuses💰 RVU & Reimbursement Profile
| Component | Value |
|---|---|
| Work RVU | 18.14 |
| Global Period | 010 |
| Bilateral Indicator | 1 |
| Assistant Surgeon | 1 — Statutory payment restriction applies; assistant at surgery may not be paid under usual Medicare rules |
| Co‑Surgeon | 0 — CMS co-surgery concept does not apply under the PFS indicator |
| Team Surgery | 0 — CMS team-surgery concept does not apply under the PFS indicator |
| PC/TC Split | 0 — Physician service; separate professional/technical component payment does not apply |
| Modifier -51 Exempt | No; subject to multiple-procedure rules when applicable |
| Anesthesia | Anesthesia is reported separately by the qualified anesthesia provider when medically necessary and documented |
Bilateral Billing Rules
The CMS bilateral indicator of 1 permits the bilateral-payment adjustment when the procedure is performed on both sides and payer requirements are met. Medicare generally applies the bilateral adjustment before any applicable multiple-procedure reduction. Submit -50 only when bilateral work is documented and the payer’s reporting rules permit use of that modifier; some payers instead require two line items with -RT and -LT. 1
🏷️ Modifier Reference
| Modifier | Name | When to Apply |
|---|---|---|
| -RT | Right Side | Append when the operative report supports a unilateral right-sided ethmoid-region repair and the payer requires laterality reporting. Do not append solely because the endoscope entered through the right nostril. |
| -LT | Left Side | Append when the operative report supports a unilateral left-sided ethmoid-region repair and the payer requires laterality reporting. The documented repair site controls laterality. |
| -50 | Bilateral Procedure | May apply because the PFS bilateral indicator is 1. Use only when both sides are repaired during the same session, medical necessity is documented, and payer instructions authorize modifier reporting. |
| -24 | Unrelated Evaluation and Management Service by the Same Physician or Other Qualified Health Care Professional During a Postoperative Period | Use for an unrelated E/M service during the 10-day global period. The note must establish that the E/M service is unrelated to normal postoperative management. |
| -25 | Significant, Separately Identifiable Evaluation and Management Service by the Same Physician or Other Qualified Health Care Professional on the Same Day of the Procedure or Other Service | Use only when a separately identifiable E/M service above and beyond the usual preoperative work is documented on the same date. It is appended to the E/M code, not to 31290. |
| -51 | Multiple Procedures | May be used when multiple separately reportable procedures are performed during the same session, subject to payer reporting rules. Do not use it to unbundle integral endoscopic services. |
| -52 | Reduced Services | Use when the intended service is partially reduced at the physician’s election and the record explains what was not performed. Do not use for an aborted procedure caused by extenuating circumstances after anesthesia or surgical preparation. |
| -53 | Discontinued Procedure | Use when the procedure is started but discontinued because of extenuating circumstances or a threat to patient well-being. The operative report must document the reason and the work completed. |
| -54 | Surgical Care Only | May apply when one physician performs the procedure and another physician provides all postoperative care during the global period. A formal transfer-of-care arrangement and payer-specific requirements apply. |
| -55 | Postoperative Management Only | May apply to the physician who provides postoperative management only after a qualifying transfer of care. Use only for the postoperative portion of the global package. |
| -56 | Preoperative Management Only | May apply when a physician provides only preoperative management under a documented transfer-of-care arrangement. It is not used for routine preoperative evaluation performed by the operating surgeon. |
| -58 | Staged or Related Procedure or Service by the Same Physician or Other Qualified Health Care Professional During the Postoperative Period | Use for a planned or staged related procedure during the global period when the documentation supports modifier criteria. The subsequent procedure begins a new global period when applicable. |
| -59 | Distinct Procedural Service | Use only for a separate encounter, separate lesion, separate site, or independent service when supported by documentation and no more specific modifier applies. It cannot be used simply to obtain payment for services bundled into 31290. |
| -78 | Unplanned Return to the Operating/Procedure Room by the Same Physician or Other Qualified Health Care Professional Following Initial Procedure for a Related Procedure During the Postoperative Period | Use when an unplanned related return to the operating or procedure room occurs during the 10-day global period. The original global period continues. |
| -79 | Unrelated Procedure or Service by the Same Physician or Other Qualified Health Care Professional During the Postoperative Period | Use for an unrelated procedure during the global period when documentation establishes no relationship to the original CSF-leak repair. A new global period begins for the unrelated procedure when applicable. |
🩺 Common ICD‑10‑CM Pairings
Primary Diagnosis Group
| ICD‑10 | Description | HCC? | Notes |
|---|---|---|---|
| G96.01 | Cranial cerebrospinal fluid leak, spontaneous | No | Use when the provider documents a spontaneous cranial CSF leak. The 2026 ICD-10-CM instruction includes a code-also note for intracranial hypotension when applicable. |
| G96.08 | Other cranial cerebrospinal fluid leak | No | Use for a cranial CSF leak that is not documented as spontaneous and does not meet a more specific code. Confirm the causal condition and code it when documented. |
| G96.00 | Cerebrospinal fluid leak, unspecified | No | Use only when the record does not establish cranial versus spinal location or other specificity. Query when the operative report clearly identifies a cranial ethmoid-region leak but the diagnosis documentation is nonspecific. |
Secondary Group
| ICD‑10 | Description | HCC? | Notes |
|---|---|---|---|
| J34.89 | Other specified disorders of nose and nasal sinuses | No | May be reported when documented and clinically relevant; it is not a substitute for coding the confirmed CSF leak. The ICD-10-CM listing for cranial CSF leak identifies this code as an additional code. |
| Q01.8 | Encephalocele of other sites | No | Report when an encephalocele is documented and clinically evaluated or treated. Do not infer an encephalocele solely from the presence of a skull-base defect. |
Etiology / Complication
| ICD‑10 | Description | HCC? | Notes |
|---|---|---|---|
| G96.811 | Intracranial hypotension, spontaneous | No | Report only when separately documented as associated with the spontaneous cranial CSF leak. The subcategory instruction for CSF leak directs coders to code also intracranial hypotension when applicable. |
| G97.0 | Cerebrospinal fluid leak from spinal puncture | No | Do not use for an ethmoid-region cranial leak. It is excluded from the CSF-leak subcategory and describes a distinct spinal-puncture complication. |
Coding Specificity Reminder
Select the most specific documented CSF-leak diagnosis. For an ethmoid-region repair, avoid defaulting to G96.00 when the provider documents a cranial leak and supports a more specific cranial CSF-leak code. Do not code a suspected cause, such as trauma, postoperative complication, or encephalocele, unless provider documentation supports it. 3
🏥 MS‑DRG Considerations
CPT 31290 does not independently assign an MS-DRG because MS-DRGs are calculated for inpatient discharges from the complete ICD-10-CM diagnosis and ICD-10-PCS procedure code set. The principal diagnosis may be the cranial CSF leak, an underlying congenital defect, traumatic condition, or a postoperative complication, depending on the circumstances documented after study. For inpatient reporting, code the endoscopic repair with the ICD-10-PCS code that reflects the actual body part, approach, device, and qualifier; an ethmoid-bone repair may be coded with a right or left ethmoid-bone PCS value when supported. No code-specific NCD was identified, and no universally applicable LCD for 31290 was identified in the CMS Medicare Coverage Database review; local coverage and billing requirements may vary by MAC and jurisdiction. The CMS PFS Lookup/PFS RVU data govern national Medicare payment indicators, not medical-necessity coverage determinations.145
🔧 ICD‑10‑PCS Equivalents
| PCS Code | Full Description | Modality |
|---|---|---|
| 0NQF4ZZ | Repair Right Ethmoid Bone, Percutaneous Endoscopic Approach | Endoscopic |
| 0NQG4ZZ | Repair Left Ethmoid Bone, Percutaneous Endoscopic Approach | Endoscopic |
| 0NQF0ZZ | Repair Right Ethmoid Bone, Open Approach | Open |
| 0NQG0ZZ | Repair Left Ethmoid Bone, Open Approach | Open |
The CPT-to-PCS relationship is not one-to-one. These PCS examples represent repair of the right or left ethmoid bone when the documented inpatient procedure supports that body part and approach; final PCS selection must follow the full operative report and 2026 Official Guidelines. A nasal endoscopic approach typically supports the percutaneous endoscopic approach value when the PCS approach definition is met. 5
PCS Character Analysis
| Position | Character | Value | Definition |
|---|---|---|---|
| 1 | Section | 0 | Medical and Surgical. This section contains operative procedures performed to treat disease or restore body structure and function. |
| 2 | Body System | N | Head and Facial Bones. The ethmoid bone is classified in this PCS body system. |
| 3 | Root Operation | Q | Repair. Repair means restoring, to the extent possible, a body part to its normal anatomic structure and function. |
| 4 | Body Part | F or G | F identifies right ethmoid bone and G identifies left ethmoid bone. Select laterality from the documented repair site. |
| 5 | Approach | 4 or 0 | 4 is percutaneous endoscopic and 0 is open. The approach is determined from the PCS definition and operative technique, not from CPT code title alone. |
| 6 | Device | Z | No device. Use another value only if a device remains in place at the end of the procedure and the PCS table directs that value. |
| 7 | Qualifier | Z | No qualifier. Select a different qualifier only when the PCS table and procedure documentation support it. |
Root Operation Comparison
- Repair is appropriate when the objective is to restore the ethmoid-region defect or skull-base structure to normal anatomic function. The surgical intent, rather than incidental technique, drives root-operation assignment.
- Supplement may apply instead when the objective is to reinforce or augment a body part with biologic or synthetic material rather than restore its native structure. Review the operative report and applicable PCS tables before final coding.
- Control is not assigned merely because hemostasis occurs during repair. Use it only when the objective of the procedure is stopping postprocedural or other acute bleeding as defined by PCS.
📝 Coding Examples
Example 1
Clinical Scenario: A patient with documented spontaneous right ethmoid-region cranial CSF leak undergoes endoscopic surgical repair. The operative report identifies the right ethmoid skull-base defect, confirms closure of the CSF leak, and describes the repair technique. No separate, significant E/M service is documented on the procedure date.
| Field | Code | Rationale |
|---|---|---|
| CPT | 31290--RT | 31290 represents endoscopic repair of the CSF leak in the ethmoid region. -RT may be appended when required by the payer and supported by explicit right-sided documentation. |
| PDx | G96.01 | The provider documented a spontaneous cranial CSF leak. |
Note
Confirm payer-specific laterality reporting before submitting -RT. Do not report a diagnostic nasal endoscopy separately when it is integral to the surgical repair.
Example 2
Clinical Scenario: A patient undergoes endoscopic repair of medically necessary right and left ethmoid-region CSF-leak defects during the same operative session. The surgeon separately documents repair work on both sides. The payer accepts bilateral reporting using the bilateral-procedure modifier.
| Field | Code | Rationale |
|---|---|---|
| CPT | 31290--50 | The bilateral indicator of 1 allows bilateral adjustment when bilateral work is documented and payer instructions permit -50. |
| PDx | G96.08 | The provider documents a cranial CSF leak without stating that it is spontaneous. |
Warning
Example 3
Clinical Scenario: Six days after an ethmoid-region CSF-leak repair, the same surgeon returns the patient to the operating room for an unplanned related repair of recurrent leakage. The operative report describes recurrent CSF rhinorrhea, the related defect, and the additional operative repair.
| Field | Code | Rationale |
|---|---|---|
| CPT | 31290--78 | -78 identifies an unplanned related return to the operating or procedure room during the original global period. |
| PDx | G96.08 | The diagnosis supports the documented recurrent cranial CSF leak when no more specific cause is documented. |
Global period reminder
-78 does not start a new global period. The original 10-day global period continues.
⚠️ Common Coding Pitfalls
- Pitfall 1: Reporting 31290 for a diagnostic nasal endoscopy or sinus examination without documented repair of a CSF leak. The procedure note must establish actual repair and the ethmoid-region location.
- Pitfall 2: Selecting 31290 when the repair is documented in the sphenoid region. Use 31291 for sphenoid-region CSF-leak repair because the anatomic site determines code selection.
- Pitfall 3: Reporting 31231 separately when diagnostic endoscopy is integral to the same-session surgical repair. Separate reporting requires a truly distinct service that meets current payer and NCCI requirements.
- Pitfall 4: Using G96.00 when the record documents a cranial leak and supports G96.01 or G96.08. Use the highest documented diagnosis specificity and query the provider if necessary.
- Pitfall 5: Appending -50, -RT, or -LT without clear laterality in the operative report. Nasal access through one nostril does not by itself establish the side of the repaired ethmoid-region defect.
- Pitfall 6: Billing an assistant-at-surgery modifier when Medicare’s PFS assistant-surgery indicator does not permit routine payment. Review the current PFS indicator and payer policy before claim submission; documentation alone does not override a statutory payment restriction.
📎 Sources
1 Centers for Medicare & Medicaid Services. Medicare Physician Fee Schedule Look-Up Tool and 2026 PFS Relative Value Files, 2026. PFS comparison points for CPT 31290: work RVU 18.14, global period 010, bilateral indicator 1, PC/TC indicator 0, assistant-at-surgery indicator 1, co-surgeon indicator 0, team-surgery indicator 0.
2 American Academy of Otolaryngology-Head and Neck Surgery and AAPC CPT code reference materials, 2026. CPT 31290 identifies surgical nasal/sinus endoscopy with repair of CSF leak in the ethmoid region; CPT 31291 identifies sphenoid-region repair.
3 Centers for Medicare & Medicaid Services. ICD-10-CM Official Guidelines for Coding and Reporting and FY 2026 ICD-10-CM code set, 2026. See valid codes G96.00, G96.01, G96.08, G96.811, G97.0, J34.89, and Q01.8.
4 Centers for Medicare & Medicaid Services. Medicare Coverage Database Search, reviewed August 10, 2026. No universally applicable code-specific NCD or LCD for CPT 31290 was identified; verify MAC and jurisdiction-specific requirements before billing.
5 Centers for Medicare & Medicaid Services. FY 2026 ICD-10-PCS Official Guidelines and PCS Table 0NQ, Repair of Head and Facial Bones, 2026. Ethmoid-bone values include right ethmoid bone and left ethmoid bone; final PCS assignment depends on operative-report details.
Sources listed above correspond to superscript citations throughout this note. Verify all Medicare payment figures against your current CMS PFS Lookup tool and applicable MAC LCD prior to claim submission. Please use the latest AAPC/AHIMA Coding Books to verify each code within this note.