Which option best describes a post-traumatic pseudoaneurysm?

• A. A swirling pocket of blood attached to the artery by a neck
• B. True aneurysm
• C. Dissection
• D. Post-traumatic pseudoaneurysm

Answer: (D)

A post-traumatic pseudoaneurysm forms when injury to the arterial wall causes blood to escape into surrounding tissue but remains in contact with the artery through a narrow neck. The blood is contained by the surrounding tissues rather than by all the wall layers of the vessel, so you get a pulsatile hematoma that communicates with the arterial lumen. The explicit description “post-traumatic pseudoaneurysm” is the best choice here because it specifies both the mechanism (trauma) and the lesion type (pseudoaneurysm).

Describing a pseudoaneurysm without the trauma context captures the same vascular lesion, but it doesn’t indicate the post-traumatic cause, which is what the question is emphasizing. A true aneurysm involves dilation of all vessel-wall layers, not a contained breach with a neck, and dissection refers to a tear within the wall creating a false lumen, not a separate pulsatile hematoma connected by a neck.