Abdominal aortic aneurysm can impinge which adjacent structures?

• A. Vertebrae and ureter
• B. Liver and stomach
• C. Lung and diaphragm
• D. Spleen and pancreas

Answer: (A)

Abdominal aortic aneurysms expand in the retroperitoneal space right along the aorta, which lies close to the vertebral column and the paths of the ureters. As the aneurysm enlarges, it can exert mass effect on nearby structures. The vertebral bodies sit directly posterior to the aorta, so an expanding aneurysm can irritate or erode into them, causing back pain or structural changes. The ureters run retroperitoneally and cross near the aorta as they descend to the bladder; an enlarging aneurysm can compress a ureter, potentially leading to hydronephrosis on the affected side. In contrast, the liver and stomach are higher in the abdomen and intraperitoneal, the lungs and diaphragm are thoracic, and the spleen and pancreas are not typically adjacent to the abdominal aorta in a way that a standard aneurysm would impinge them. Therefore, the structures most likely to be affected by an abdominal aortic aneurysm are the vertebrae and the ureter.