UWorld Internal Medicine Practice Test

In the context of a patient presenting with chest pain and pericardial effusion, viral infection is the most likely cause. This is particularly true given the epidemiology of pericarditis, which often arises in the setting of viral infections, especially those caused by common viruses such as coxsackievirus, echovirus, or influenza.

Viral pericarditis tends to present acutely with symptoms including sharp chest pain that may worsen with inspiration or when lying down. The inflammatory response triggered by the viral infection can lead to the accumulation of fluid in the pericardial space, resulting in pericardial effusion.

While autoimmune diseases, coronary artery disease, and malignancy can also lead to pericardial effusion, often the presentation is less acute compared to viral etiology. In autoimmune diseases, the effusion might be chronic or associated with other systemic symptoms. Coronary artery disease typically presents with ischemic chest pain rather than inflammation leading to fluid accumulation. Malignancy generally results in effusion due to advanced disease processes or metastasis, which may not initially present with classical chest pain associated with inflammation.

Given these factors, the association between viral infections and acute pericarditis makes viral infection