Educational Content: This article is for informational purposes only and does not constitute medical advice. Always consult a healthcare provider for diagnosis and treatment.
Definition of Effusion, pericardial
Medically reviewed by Min Clinic Staff | Updated: January 2026
Effusion, pericardial: Too much fluid within the fibrous sac (pericardium) that surrounds the heart. The inner surface of the pericardium is lined by a layer of flat cells (mesothelial cells) that normally secrete a small amount of fluid, which acts as a lubricant to allow normal heart movement within the chest. A pericardial effusion involves the presence of an excessive amount of pericardial fluid, a pale yellow serous fluid, within the pericardium.