Intensive Care Medicine (ICM) Practice Exam

Which radiographic sign is indicative of a pulmonary embolus?

1. Hampton's hump

2. Blunting of costophrenic angles

3. Air bronchograms

4. Silhouette sign

The correct answer is: Hampton's hump

Hampton's hump is a notable radiographic sign that suggests the presence of a pulmonary embolism. It is characterized by a wedge-shaped opacity at the periphery of the lung, often seen on a chest X-ray. This appearance arises from the infarction of lung tissue that occurs as a result of the obstruction of a pulmonary artery, which reduces blood flow and leads to ischemia and subsequent necrosis of the affected lung segment. The "hump" is a reflection of the pleura and edema surrounding the infarcted area. Understanding the other choices helps to clarify why they are not indicative of pulmonary embolus. Blunting of costophrenic angles is typically associated with pleural effusion rather than embolic events. Air bronchograms indicate the presence of air in the bronchi surrounded by consolidated or fluid-filled alveoli, which is more characteristic of pneumonia or atelectasis. The silhouette sign represents loss of normal silhouette due to adjacent structures becoming indistinguishable on imaging, primarily seen in conditions like pneumonia or atelectasis rather than in cases of pulmonary embolism. In summary, Hampton's hump is the hallmark radiographic finding associated with pulmonary embolism due to the presence of ischemic lung tissue following vascular occlusion, distinguishing it