ICD10BillableValid for clinical use
ICD-10 Code J21.9: Acute bronchiolitis, unspecified
Reviewed by HealthAssure Clinical TeamUpdated 26 May 2026
What is this code?
ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Diseases of the respiratory system (J00-J99).
When is it used?
- May be used when a clinician documents acute bronchiolitis, unspecified in a patient's medical record.
- May appear in hospital records, claims, referrals, and clinical documentation.
- This code can be used as a clinically usable diagnosis entry in standardized coding workflows.
What it does not mean
- A code alone does not explain severity, treatment plan, or outcome.
- A medical code should not be treated as a substitute for a doctor's diagnosis or advice.
Code hierarchy
chapter
10Diseases of the respiratory system (J00-J99)
block
J20-J22Other acute lower respiratory infections
category
J21Acute bronchiolitis
currentJ21
Official coding notes
Inclusion terms
- Bronchiolitis (acute)
Excludes1 (do not code together)
- chronic bronchiolitis (J44.89)
Where you may see this code
You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.
Related specialists
PulmonologistGeneral Physician
Related codes
Sibling codes
Coverage-related procedures and services
CPT 87801high
INFECTIOUS AGENT DETECTION BY NUCLEIC ACID (DNA OR RNA), MULTIPLE ORGANISMS; AMPLIFIED PROBE(S) TECHNIQUE
Source: CMS coverage guidance
CPT 87631high
INFECTIOUS AGENT DETECTION BY NUCLEIC ACID (DNA OR RNA); RESPIRATORY VIRUS (EG, ADENOVIRUS, INFLUENZA VIRUS, CORONAVIRUS, METAPNEUMOVIRUS, PARAINFLUENZA VIRUS, RESPIRATORY SYNCYTIAL VIRUS, RHINOVIRUS), INCLUDES MULTIPLEX REVERSE TRANSCRIPTION, WHEN PERFORMED, AND MULTIPLEX AMPLIFIED PROBE TECHNIQUE, MULTIPLE TYPES OR SUBTYPES, 3-5 TARGETS
Source: CMS coverage guidance
CPT 87636high
INFECTIOUS AGENT DETECTION BY NUCLEIC ACID (DNA OR RNA); SEVERE ACUTE RESPIRATORY SYNDROME CORONAVIRUS 2 (SARS-COV-2) (CORONAVIRUS DISEASE [COVID-19]) AND INFLUENZA VIRUS TYPES A AND B, MULTIPLEX AMPLIFIED PROBE TECHNIQUE
Source: CMS coverage guidance
CPT 87637high
INFECTIOUS AGENT DETECTION BY NUCLEIC ACID (DNA OR RNA); SEVERE ACUTE RESPIRATORY SYNDROME CORONAVIRUS 2 (SARS-COV-2) (CORONAVIRUS DISEASE [COVID-19]), INFLUENZA VIRUS TYPES A AND B, AND RESPIRATORY SYNCYTIAL VIRUS, MULTIPLEX AMPLIFIED PROBE TECHNIQUE
Source: CMS coverage guidance
CPT 31720high
CATHETER ASPIRATION (SEPARATE PROCEDURE); NASOTRACHEAL
Source: CMS coverage guidance
CPT 94664high
DEMONSTRATION AND/OR EVALUATION OF PATIENT UTILIZATION OF AN AEROSOL GENERATOR, NEBULIZER, METERED DOSE INHALER OR IPPB DEVICE
Source: CMS coverage guidance
Mapped diagnoses and classifications
SNOMED_CT 5505005high
Acute bronchiolitis
Source: SNOMED International ICD-10 map
SNOMED_CT 15199004high
Acute bronchiolitis with bronchospasm
Source: SNOMED International ICD-10 map
SNOMED_CT 718004high
Acute bronchiolitis with obstruction
Source: SNOMED International ICD-10 map
SNOMED_CT 195737004high
Acute exudative bronchiolitis
Source: SNOMED International ICD-10 map
SNOMED_CT 4120002high
Bronchiolitis
Source: SNOMED International ICD-10 map
SNOMED_CT 52409006high
Bronchiolitis exudativa
Source: SNOMED International ICD-10 map
Coding guidelines
Compatibility
Legacy and official ICD code match exactly.
Legacy codes
J21.9
Common synonyms
Acute bronchiolitis, unspecifiedAcute bronchiolitis
Frequently asked questions
About this content
This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.