ICD-10 Code I31.31 – Malignant pericardial effusion in diseases classified elsewhere (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code I31.31 – Malignant pericardial effusion in diseases classified elsewhere
What it is
This code identifies a pericardial effusion caused by a malignant condition classified elsewhere. Use it when fluid has accumulated in the pericardial sac and the record links it to cancer or another neoplastic process.
Clinical signs
Clinical features vary; refer to documentation. Common findings may include chest discomfort, dyspnea, tachycardia, or evidence of pericardial fluid on imaging or echocardiography, with a documented malignant cause.
When to use this code
Use this code when the provider documents malignant pericardial effusion and states the underlying neoplasm is the cause. It is appropriate when the effusion is secondary to cancer, metastatic disease, or another malignant process classified elsewhere. Confirm that the record supports both the effusion and its malignant etiology.
Do not use for
Do not use this code for pericardial effusion without a documented malignant cause. If the effusion is due to infection, trauma, renal disease, or another nonmalignant condition, check documentation for the correct code.
Coding tip
Code the underlying malignancy first when the chart supports it, and use I31.31 only when the pericardial effusion is clearly linked to that condition.