ICD-10 Code A37.91 – Whooping cough, unspecified species with pneumonia (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code A37.91 – Whooping cough, unspecified species with pneumonia
What it is
A37.91 identifies whooping cough, or pertussis, when the species is not specified and pneumonia is documented. Use this code when the record shows pertussis with a lower respiratory complication.
Clinical signs
Typical findings include paroxysmal coughing, inspiratory whoop, posttussive vomiting, and signs of pneumonia such as cough with respiratory distress or infiltrates. Clinical features vary; refer to documentation.
When to use this code
Use A37.91 when the provider documents pertussis with pneumonia and does not identify Bordetella species. It also fits cases where the diagnosis is confirmed clinically or by testing and pneumonia is clearly linked to the infection. If the record only says cough or bronchitis, check documentation before coding this diagnosis.
Do not use for
Do not use this code for pertussis without pneumonia, or for pneumonia not attributed to whooping cough. If the species is documented and a more specific code applies, choose that code instead.
Coding tip
Verify that pneumonia is documented as part of the pertussis episode, not just a separate respiratory finding.