ICD-10 Code J85.3 – Abscess of mediastinum (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code J85.3 – Abscess of mediastinum
What it is
J85.3 identifies a localized collection of pus in the mediastinum, the central space in the chest between the lungs. It indicates a serious deep infection that requires clear documentation.
Clinical signs
Clinical features may include chest pain, fever, and signs of severe infection or mediastinal involvement. Clinical features vary; refer to documentation.
When to use this code
Use J85.3 when the record specifically documents a mediastinal abscess or abscess of the mediastinum. It may also apply when imaging or operative findings confirm a mediastinal pus collection and the provider links it to this diagnosis. Check documentation if the note only mentions mediastinitis or another chest infection.
Do not use for
Do not use this code for pneumonia, pleural empyema, or nonspecific chest infection without mediastinal abscess documentation. Do not assume it from postoperative fever or mediastinal inflammation alone.
Coding tip
Code J85.3 only when the provider clearly states “abscess” in the mediastinum or confirms it by report.