What term describes obstruction of a blood vessel by a clot or foreign body?

• A. Embolism
• B. Hemothorax
• C. Pleural Effusion
• D. Pneumonia

Answer: (A)

The concept tested is blockage of a blood vessel by material that travels through the bloodstream and lodges in a narrower vessel. That material is called an embolus, and when it occludes a vessel, the condition is an embolism. It can be a clot (thromboembolism) or another foreign body like air or fat, but the defining idea is the traveling piece causing obstruction downstream.

The other terms refer to issues in different spaces or processes: a hemothorax is blood in the pleural space around the lungs; a pleural effusion is fluid in that space; pneumonia is an infection of the lung tissue.