In cases of moderate or large pericardial effusion, fluid can be drained, such as when the thickness of the pericardial effusion exceeds two centimeters. Draining the fluid can relieve the symptoms caused by the pericardial effusion, improve cardiac blood supply, and also allow for the collection of samples for routine and biochemical analysis of the effusion, as well as pathological examination. By analyzing the drained fluid, it is possible to determine the nature of the effusion, such as whether it is an exudate or a transudate. This can then further help in determining the cause of the effusion, where exudates are often caused by factors such as tuberculosis and cancer, while transudates are often due to heart failure or hypoproteinemia and other factors.