Specific code 2012 ICD-9-CM Diagnosis Code 491.21
Obstructive chronic bronchitis with (acute) exacerbation
  • Short description: Obs chr bronc w(ac) exac.
  • ICD-9-CM 491.21 will be replaced by an equivalent ICD-10-CM code (or codes) when the United States transitions from ICD-9-CM to ICD-10-CM on October 1, 2015.
  • ICD-9-CM 491.21 is a billable medical code that can be used to specify a diagnosis on a reimbursement claim.
  • You are viewing the 2012 version of ICD-9-CM 491.21.
  • More recent version(s) of ICD-9-CM 491.21: 2013 2014.
Disease Synonyms
  • Acute exacerbation of chronic obstructive airways disease
  • Acute exacerbation of chronic obstructive bronchitis
  • Acute exacerbation of COPD
  • Chronic obstructive bronchitis with exacerbation
  • Chronic obstructive pulmonary disease, acute flare-up
  • COPD W acute exacerbation
491.21 Excludes
  • chronic obstructive asthma with acute exacerbation 493.22
Applies To
  • Acute exacerbation of chronic obstructive pulmonary disease [COPD]
  • Decompensated chronic obstructive pulmonary disease [COPD]
  • Decompensated chronic obstructive pulmonary disease [COPD] with exacerbation
Convert to ICD-10-CM: 491.21 converts approximately to:
  • 2014 ICD-10-CM J44.1 Chronic obstructive pulmonary disease with (acute) exacerbation
ICD-9-CM Volume 2 Index entries containing back-references to 491.21:
  • Blue
    • bloater 491.20
      • with
        • acute bronchitis 491.22
        • exacerbation (acute) 491.21
  • Bronchitis (diffuse) (hypostatic) (infectious) (inflammatory) (simple) 490
    • with
      • emphysema - see Emphysema
      • influenza, flue, or grippe (see also Influenza) 487.1
      • obstruction airway, chronic 491.20
        • with
          • acute bronchitis 491.22
          • exacerbation (acute) 491.21
      • tracheitis 490
    • emphysematous 491.20
      • with
        • acute bronchitis 491.22
        • exacerbation (acute) 491.21
    • obstructive (chronic) 491.20
      • with
        • acute bronchitis 491.22
        • exacerbation (acute) 491.21
  • Disease, diseased - see also Syndrome
    • pulmonary - see also Disease, lung
      • amyloid 277.39 [517.8]
      • artery 417.9
      • circulation, circulatory 417.9
      • diffuse obstructive (chronic) 496
        • with
          • acute bronchitis 491.22
          • asthma (chronic) (obstructive) 493.2
          • exacerbation NEC (acute) 491.21
      • heart (chronic) 416.9
      • hypertensive (vascular) 416.0
      • obstructive diffuse (chronic) 496
        • with
          • acute bronchitis 491.22
          • asthma (chronic) (obstructive) 493.2
          • bronchitis (chronic) 491.20
          • exacerbation NEC (acute) 491.21
        • decompensated 491.21
          • with exacerbation 491.21
      • valve (see also Endocarditis, pulmonary) 424.3
  • Embryoma (M9080/1) - see also Neoplasm, by site, uncertain behavior
    • malignant (M9080/3) - see also Neoplasm, by site, malignant
      • kidney (M8960/3) 189.0
      • liver (M8970/3) 155.0
      • testis (M9070/3) 186.9
        • undescended 186.0
          • with
          • acute bronchitis 491.22
          • exacerbation (acute) 491.21
  • Syndrome - see also Disease
    • autosomal - see also Abnormal, autosomes NEC
ICD-9-CM codes are used in medical billing and coding to describe diseases, injuries, symptoms and conditions. ICD-9-CM 491.21 is one of thousands of ICD-9-CM codes used in healthcare. Although ICD-9-CM and CPT codes are largely numeric, they differ in that CPT codes describe medical procedures and services. Can't find a code? Start at the root of ICD-9-CM, check the 2012 ICD-9-CM Index or use the search engine at the top of this page to lookup any code.