2006 ICD-9-CM Volume 1 Diagnosis Codes Home > Diseases Of The Respiratory System 460-519 > Chronic Obstructive Pulmonary Disease And Allied Conditions 490-496 > ICD-9-CM Diagnosis 491 Chronic bronchitis A subcategory of CHRONIC OBSTRUCTIVE PULMONARY DISEASE. The disease is characterized by hypersecretion of mucus accompanied by a chronic (more than 3 months in 2 consecutive years) productive cough. Infectious agents are a major cause of chronic bronchitis. 491 is a non-specific code that cannot be used to specify a diagnosis ICD-9-CM Diagnosis 491.0 Simple chronic bronchitis 491.0 is a specific code that can be used to specify a diagnosis 491.0 contains 12 index entries ICD-9-CM Diagnosis 491.1 Mucopurulent chronic bronchitis 491.1 is a specific code that can be used to specify a diagnosis 491.1 contains 8 index entries ICD-9-CM Diagnosis 491.2 Obstructive chronic bronchitis 491.2 is a non-specific code that cannot be used to specify a diagnosis ICD-9-CM Diagnosis 491.20 Obstructive chronic bronchitis without exacerbation 491.20 is a specific code that can be used to specify a diagnosis 491.20 contains 12 index entries ICD-9-CM Diagnosis 491.21 Obstructive chronic bronchitis with (acute) exacerbation 491.21 is a specific code that can be used to specify a diagnosis 491.21 contains 12 index entries ICD-9-CM Diagnosis 491.22 Obstructive chronic bronchitis with acute bronchitis 491.22 is a specific code that can be used to specify a diagnosis 491.22 contains 12 index entries ICD-9-CM Diagnosis 491.8 Other chronic bronchitis 491.8 is a specific code that can be used to specify a diagnosis 491.8 contains 18 index entries ICD-9-CM Diagnosis 491.9 Unspecified chronic bronchitis A subcategory of CHRONIC OBSTRUCTIVE PULMONARY DISEASE. The disease is characterized by hypersecretion of mucus accompanied by a chronic (more than 3 months in 2 consecutive years) productive cough. Infectious agents are a major cause of chronic bronchitis. 491.9 is a specific code that can be used to specify a diagnosis 491.9 contains 4 index entries