Which term best describes a vessel weakness forming a bubble?

• A. Aneurysm
• B. Subarachnoid hemorrhage
• C. Embolism
• D. Watershed infarct

Answer: (A)

An aneurysm is a localized dilation or outpouching of a blood vessel caused by weakness in the vessel wall. In the brain, this often appears as a bubble-like bulge at a bifurcation, sometimes called a berry aneurysm, which matches the description of a vessel weakness forming a bubble. Subarachnoid hemorrhage would be the bleeding that can occur if such an aneurysm ruptures, not the dilation itself. An embolism refers to a clot or debris that travels and blocks a vessel, and a watershed infarct describes tissue damage from low blood flow at border zones between arterial territories. So the term that best fits the described vessel change is aneurysm.