Which term refers to dilation or ballooning of a weakened vessel?

• A. Embolism
• B. Aneurysm
• C. Thrombosis
• D. Hemorrhage

Answer: (B)

Dilation or ballooning of a weakened vessel is an aneurysm. It happens when a segment of the vessel wall becomes weakened so the normal arterial pressure stretches it outward, forming a sac-like widening. This can be a true aneurysm, involving all layers of the vessel wall, or a pseudoaneurysm where the breach is contained by surrounding tissue.

An embolism describes material that travels and blocks a vessel, not dilation. Thrombosis is clot formation within a vessel, which narrows or occludes flow. Hemorrhage is active bleeding from a vessel, which may occur if an aneurysm ruptures, but it’s the ballooning itself that defines an aneurysm.