ICD-10 Code J98.51 – Mediastinitis (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code J98.51 – Mediastinitis
What it is
Mediastinitis is inflammation or infection of the mediastinum, the central space in the chest between the lungs. Use this code when the documentation clearly identifies mediastinitis.
Clinical signs
Clinical features vary; refer to documentation. Common references describe chest pain, fever, shortness of breath, and signs of serious infection, but you should code only when mediastinitis is recorded.
When to use this code
Use J98.51 when the provider documents mediastinitis as the diagnosis, including postoperative or infectious cases if specified. It may also apply when imaging, operative findings, or discharge notes confirm mediastinal inflammation and the final assessment names mediastinitis.
If the record only suggests mediastinal abnormality, chest infection, or postoperative pain without a diagnosis of mediastinitis, check documentation before assigning this code. Code the confirmed condition, not the suspected source.
Do not use for
Do not use this code for isolated pneumonia, pleurisy, or general chest pain without mediastinal involvement. If the chart does not clearly state mediastinitis, check documentation.
Coding tip
Look for the exact phrase “mediastinitis” in the final provider assessment, not just in test results or differential diagnoses.