Summary & Overview

HCPCS G9350: CT Scan of Paranasal Sinuses, Delayed or Not Ordered at Diagnosis

HCPCS Level II code G9350 denotes a computed tomography (CT) scan of the paranasal sinuses that was either not ordered at the time of initial diagnosis or was not performed within 28 days after that diagnosis. This designation matters nationally because it affects how delayed diagnostic imaging is categorized for billing and quality measurement, and can influence coverage determinations and administrative reporting for imaging services.

Key payers reviewed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of the code’s clinical context, how the service is typically delivered (diagnostic CT in outpatient radiology or hospital outpatient settings), and the implications for coding and claims processing when imaging occurs outside the initial diagnostic window. The publication summarizes common modifiers and associated administrative considerations when available, and highlights where input data are not present.

The report is intended for billing professionals, clinical administrators, and policy analysts seeking a concise reference for G9350. It covers what the code represents, typical sites of service, payer coverage scope, and notes on missing contextual data. Benchmarks, policy updates, and payer-specific coverage details are summarized when available; where data were not provided in the input, the text indicates that those data are not available.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicareG9350HCPCS Level IIparanasal sinusesCT scandiagnostic imagingoutpatient radiologymedical codingimaging delaybilling compliance

Billing Code Overview

HCPCS Level II code G9350 describes a CT scan of the paranasal sinuses that was not ordered at the time of diagnosis or not received within 28 days after the date of diagnosis. This code captures imaging performed outside the initial diagnostic window defined in the description.

Service type: Diagnostic imaging (computed tomography of the paranasal sinuses)
Typical site of service: Outpatient radiology or ambulatory imaging centers; may also be performed in hospital outpatient departments when imaging occurs after the initial diagnostic period

Data not available in the input.

Clinical & Coding Specifications

Clinical Context

A typical patient is an adult presenting to an outpatient otolaryngology clinic or emergency department with persistent unilateral nasal obstruction, facial pain, or suspected complicated acute rhinosinusitis after initial conservative management. Initial clinical evaluation and nasal endoscopy suggest possible sinusitis or anatomic variation (eg, obstructed ostiomeatal complex) but no CT was ordered at the time of initial diagnosis. The clinician orders a diagnostic CT of the paranasal sinuses; the study is scheduled and performed within 28 days after the date of diagnosis when symptoms persist or worsen.

Common workflow: the patient is triaged and examined by a primary care clinician or emergency physician, referred to otolaryngology if red flags or nonresponse are present, imaging is ordered with indication documented in the chart, prior authorization is obtained if required, the CT is performed in the radiology department or outpatient imaging center, and images are interpreted by a radiologist with findings communicated to the ordering clinician.

Coding Specifications

Modifier	Description	When to Use
`22`	Increased procedural services	Use when work required to perform or interpret the CT is substantially greater than typically required (document rationale and extra work).
`23`	Unusual anesthesia	Use when general anesthesia or deep sedation is used for the CT for an unusual circumstance (document reason).
`52`	Reduced services	Use when the CT study is partially reduced or not fully completed (document extent and reason).
`53`	Discontinued procedure	Use if the CT is started but terminated prior to completion for patient safety or intolerance (document reason).
`54`	Surgical care only	Rarely applicable; use when diagnostic imaging is billed separately and only surgical component is relevant for another provider.
`55`	Postoperative management only	Use when another provider bills for postoperative care separate from the imaging service.
`56`	Preoperative management only	Use when preoperative evaluation is billed separately from the imaging service.
`62`	Two surgeons	Use when two surgeons of different specialties are required for concurrent procedures related to sinus surgery and imaging coordination (document).
`AS`	Ambulatory surgical center facility	Use to indicate the service was rendered in an ambulatory surgical center when applicable.
`QX`	CLIA waived test performed by an individual with distinct qualifications	Use when point-of-care testing associated with visit meets criteria and is billed alongside imaging (rare).

Taxonomy Code	Specialty	Notes
Data not available in the input.	Data not available in the input.	Data not available in the input.
Data not available in the input.	Data not available in the input.	Data not available in the input.
Data not available in the input.	Data not available in the input.	Data not available in the input.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`J01.90`	Acute sinusitis, unspecified	Common indication when acute sinus symptoms persist or worsen and CT is needed for complication assessment or surgical planning.
`J32.9`	Chronic sinusitis, unspecified	Frequent reason for CT imaging to evaluate chronic sinonasal inflammation, extent of disease, and anatomic contributors.
`J01.01`	Acute maxillary sinusitis	Maxillary sinus symptoms often prompt CT to assess sinus opacification, drainage pathways, and ostiomeatal complex.
`J01.00`	Acute sphenoidal sinusitis, unspecified	Sphenoid involvement may require CT to assess bony anatomy and proximity to skull base.
`J01.10`	Acute frontal sinusitis, unspecified	Frontal sinus disease evaluation benefits from CT for surgical planning and complication detection.
`R09.81`	Nasal congestion	Symptom that can prompt imaging when persistent or associated with other focal signs.
`H70.0`	Mastoiditis, acute	Complication of sinus or ear infections where CT of contiguous structures may be indicated to evaluate spread.
`G44.1`	Vascular headache, not elsewhere classified	Headache presentations may prompt sinus CT when sinusitis is considered in differential diagnosis.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`70486`	CT maxillofacial without contrast	Often used interchangeably or as the technical CPT for CT of paranasal sinuses when limited to the sinuses without contrast; may be billed alongside or instead of other sinus CT codes depending on facility coding.
`70488`	CT maxillofacial with contrast	Used when intravenous contrast is required for evaluation of suspected complications or vascular involvement; may follow noncontrast sinus CT if additional detail is needed.
`70490`	CT maxillofacial without and with contrast	Used when both noncontrast and contrast-enhanced imaging are performed in the same session for comprehensive assessment.
`70543`	MRI of facial bones/entire orbits with contrast	Occasionally used when MRI is indicated after CT to assess soft tissue or intracranial extension; complementary modality in complex cases.
`31276`	Nasal/sinus endoscopy, surgical, with tissue removal	May be performed in the workflow following CT confirmation of disease requiring operative intervention; imaging guides surgical planning.