Pericardial Effusion Classification by Severity

Pericardial effusion is typically classified based on the volume of fluid accumulated around the heart. It is generally categorized into four levels: minimal, small, moderate, and large. In a healthy heart, the pericardial space is a potential cavity that contains approximately 10-20 mL of fluid, which serves as a lubricant for the heart's movement. This small amount of fluid is not detectable through imaging techniques such as echocardiography, CT scans, or MRI.

Minimal Pericardial Effusion

Minimal pericardial effusion usually refers to the presence of about 30-50 mL of fluid. It is often identified as a 3-5 mm layer of fluid observed behind the left ventricular wall. However, no fluid accumulation is typically visible in front of the right ventricle.

Small Pericardial Effusion

A small pericardial effusion generally involves approximately 50-100 mL of fluid. In this case, a fluid layer measuring 5-10 mm in thickness can be seen along the posterior wall of the left ventricle. Similar to minimal effusion, there is usually no detectable fluid accumulation in front of the right ventricle.

Moderate Pericardial Effusion

Moderate effusion corresponds to a fluid volume of around 200-500 mL. In this classification, fluid accumulation of about 10 mm is visible behind the left ventricle. Additionally, fluid thickness of 10-15 mm may be observed along the anterior wall of the right ventricle, indicating a more significant build-up of fluid around the heart.

Large Pericardial Effusion

Large pericardial effusion refers to fluid volumes exceeding 500 mL. In such cases, fluid layers measuring 10-15 mm can be detected behind the left ventricle, while the anterior wall of the right ventricle may show fluid accumulation of up to 15 mm or even 30 mm in severe cases. This level of effusion can pose serious health risks and may require medical intervention.