Which of the following is NOT a potential cause of pleural effusion?

A pleural effusion refers to the accumulation of excess fluid in the pleural cavity, which can hinder normal respiratory function. Common causes of pleural effusion include conditions such as heart failure, pneumonia, and trauma, which can all lead to increased fluid production or decreased fluid absorption in the pleural space.

Heart failure can lead to increased hydrostatic pressure in the pulmonary circulation, causing fluid to leak into the pleural cavity. Pneumonia, especially when associated with infection, can trigger inflammation that subsequently increases fluid production in the pleural space as part of the body's response to the infection. Similarly, trauma, particularly to the thoracic region, can cause bleeding or fluid accumulation in the pleural cavity due to injury to blood vessels or the pleura itself.

In contrast, a hernia does not typically affect the pleural cavity or the mechanisms that lead to pleural effusion. Hernias primarily involve the protrusion of tissue through a weak area in the abdominal wall or surrounding muscle, and while they can cause a variety of complications, they do not directly contribute to fluid accumulation in the pleural space. Therefore, among the listed options, a hernia is the condition that is not associated with the development of pleural effusion.