Pericardial fluid is a common finding on echocardiography. Less than 10 mm of fluid on ultrasound scan is not necessarily associated with any significant illness. Clinical examination, blood count, renal and liver enzymes and thyroid function tests as well as inflammatory marker tests are often adequate for a patient who is in good health. A significant amount of fluid requires further investigations, especially in a symptomatic patient. Cancers, infections and various systemic diseases are the most common causes of prominent effusion.