What is the difference between a true aneurysm and a false aneurysm?

The difference between a true aneurysm and a pseudoaneurysm is mainly reflected in ultrasound images.

Ultrasound examination of a true aneurysm can reveal that the vessel wall is thinner, and the weak arterial wall gradually bulges outward when blood passes through it. The entire vessel wall is relatively intact, and may suddenly rupture when subjected to external impact or elevated blood pressure.

Ultrasound of a pseudoaneurysm shows cystic dark areas beside the artery, blood flowing out of the arterial wall and forming hematoma locally in the arterial wall. Blood enters the aneurysm from the artery during systole, and blood returns from the break to the artery during diastole.