I31.31 Malignant pericardial effusion in diseases classified elsewhere

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Code first

• underlying neoplasm (C00-D49)

Applies from I31 Other diseases of pericardium

Excludes1 (never code together)

• diseases of pericardium specified as rheumatic (I09.2)
• postcardiotomy syndrome (I97.0)
• traumatic injury to pericardium (S26.-)

Applies from I31.3 Pericardial effusion (noninflammatory)

Excludes1 (never code together)

• acute pericardial effusion (I30.9)

Risk adjustment (HCC)

• CMS-HCC V28: HCC 17 — Cancer Metastatic to Lung, Liver, Brain, and Other Organs; Acute Myeloid Leukemia Except Promyelocytic

MS-DRG index

Defines the logic of DRG(s) 314-316 in MDC 05.

Medicare Code Edits (MCE v43.1 (April 2026))

• Manifestation codes as principal diagnosis: Manifestation codes describe the manifestation of an underlying disease, not the disease itself, and are not allowed as principal diagnosis.

Code annotations containing back-references to I31.31

Back-references to I31.31

• Type 1 Excludes: I31.2 Hemopericardium, not elsewhere classified ("malignant pericardial effusion (I31.31)")

Back-references to I31

• Type 1 Excludes: I09.2 Chronic rheumatic pericarditis ("chronic pericarditis not specified as rheumatic (I31.-)")

Diagnosis Index entries for I31.31

• Effusion › pericardium, pericardial (noninflammatory) › malignant, in disease classified elsewhere

Nearby codes

• I31 Other diseases of pericardium
• I31.0 Chronic adhesive pericarditis
• I31.1 Chronic constrictive pericarditis
• I31.2 Hemopericardium, not elsewhere classified
• I31.3 Pericardial effusion (noninflammatory)
• I31.31 Malignant pericardial effusion in diseases classified elsewhere (this code)
• I31.39 Other pericardial effusion (noninflammatory)
• I31.4 Cardiac tamponade
• I31.8 Other specified diseases of pericardium
• I31.9 Disease of pericardium, unspecified