An iliac artery aneurysm is a localized, abnormal enlargement of one of the iliac arteries, which are major blood vessels that branch off from the abdominal aorta and supply blood to the pelvis and legs. The aneurysm forms when the arterial wall weakens and stretches, creating a bulge that can increase in size over time.

Most iliac artery aneurysms are asymptomatic and discovered incidentally during imaging for other reasons. When symptoms do occur, they may include pelvic or lower abdominal pain, back pain, or pressure on surrounding structures, such as the ureters or nerves. In some cases, the aneurysm may cause leg swelling due to compression of nearby veins.

Although small aneurysms may simply be monitored with regular imaging, larger aneurysms carry a risk of rupture, which can lead to life-threatening internal bleeding. Risk factors include smoking, high blood pressure, atherosclerosis, and a family history of aneurysms.

Diagnosis is usually confirmed by CT angiography or ultrasound. Management depends on the size and growth rate. Endovascular repair or open surgical repair may be recommended if the aneurysm reaches a certain threshold or becomes symptomatic.