The hallmark of diagnosing a pericardial effusion by echocardiography is the presence of relatively sonolucent space outside of the cardiac structures. The location, size, mobility, and consistency of the pericardial space determined by echocardiography are considered to be reliable markers for defining pericardial processes. In certain clinical scenarios, however, it may be difficult to differentiate fluid from other pericardial processes, notably subepicardial adipose tissue. This case of a 76-year-old woman, who presented with possible cardiac tamponade after permanent pacemaker implantation, demonstrates some of the potential pitfalls in the diagnosis of pericardial space abnormalities.