<div style="color: blue;"> <span style="font-size: large;">Pericardial effusion</span></div>

A pericardial effusion is characterised by build up of fluid in the pericardial space (a normal pericardiac sac contains approximately 30 - 50 mls of fluid).

Causes

* idiopathic
* inflammatory

post myocardial infarction (Dressler syndrome)
connective tissue disorders

* infectious

viral
bacterial
tuberculosis

* post surgical / trauma
* radiotherapy
* malignancy

primary : e.g pericardial mesothelioma
metastatic

* metabolic

hypothyroidism

Radiographic features in Plain film (CXR)

* a very small pericardial effusion can be occult on plain film
* there can be globular enlargement of the cardiac shadow giving a "water bottle" configuration.
* lateral CXR may show an "Oreo Cookie Sign" : a vertical lucent line directly behind sternum (epicardial fat), behind this a vertical opaque line (pericardial fluid) and behind this a vertical lucent line (pericardial fat).
* widening of the subcarinal angle without other evidence of left atrial enlargement may be an indirect clue.