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Medically Reviewed By:

2026-07-01

  • Condition
  • Arterial
  • Severity: Urgent

Peripheral Aneurysm

Also Known As: behind the knee; in the groin/thigh; clotting; showering small clots distally
Peripheral aneurysms are localized dilations of the arteries outside the aorta, most commonly occurring in the popliteal artery (behind the knee) and the femoral artery (in the groin/thigh). Unlike aortic aneurysms, peripheral aneurysms rarely rupture — their primary danger is thrombosis (clotting) and embolization (showering small clots distally), which can cause sudden loss of arterial blood flow to the extremities creating a limb-threatening scenario.


Most people know that aneurysms can form in the aorta. What is less well known is that they can also develop in the arteries behind your knee or in your groin. These are called peripheral aneurysms, and they are more common in men over 60. Unlike aortic aneurysms, peripheral aneurysms often cause problems not because they burst, but because they develop blood clots that can travel down to the feet. Catching them early gives you the best options for treatment.

Popliteal Artery Aneurysms

Popliteal artery aneurysms are the most common peripheral aneurysm, accounting for approximately 70% of all peripheral aneurysms. They are strongly associated with aortic aneurysm — 50% of patients with popliteal aneurysms also have an AAA, and 40% have bilateral popliteal aneurysms. Despite their relatively benign appearance on imaging, popliteal aneurysms are treacherous: they fill with laminated thrombus, which can suddenly embolize to the tibial arteries and cause acute limb ischemia requiring emergency intervention.

Femoral Artery Aneurysms

Femoral artery aneurysms most commonly occur at the common femoral artery in the groin. They may be true aneurysms, consisting of the entire arterial wall, or pseudoaneurysms (pulsating collections of blood outside the vessel wall contained by surrounding tissue, usually caused by prior access of the artery during catheterization). Femoral pseudoaneurysms are often treated with minimally invasive, local anesthetic procedures using ultrasound-guided thrombin injection. Sometimes, these pseudo (or false) aneurysms require surgical repair to address the hole in the artery.

Peripheral Aneurysm Symptoms

Many peripheral aneurysms are asymptomatic until a complication occurs. A pulsatile, often tender mass behind the knee or in the groin may be palpable on physical exam. Acute symptoms include sudden onset severe leg, calf, or foot pain, foot pallor, coldness of the foot, loss of pulses, loss of sensation or motor function, and foot or digit gangrene — all indicating acute limb ischemia requiring emergency treatment.

Treatment of Peripheral Aneurysms in Sarasota & Bradenton

Repair is recommended for all popliteal aneurysms larger than 2 cm or those containing significant thrombus, given the high risk of limb-threatening complications. Surgical bypass — using the patient’s own vein or a prosthetic conduit to re-route blood around the aneurysm — provides excellent long-term patency. Endovascular stent-graft placement is an alternative for selected patients and is a minimally invasive option for repair. Femoral aneurysms are repaired with graft interposition when symptomatic or growing.

SYMPTOMS

  • Pulsatile (throbbing) mass behind the knee or in the groin
  • Leg pain or cramping from emboli obstructing smaller vessels
  • Sudden severe leg pain, coldness, pallor, and pulselessness (acute thrombosis — emergency)
  • Foot ulcers or blue toe syndrome from small emboli
  • Often discovered incidentally on imaging

DIAGNOSIS METHODS

  • Duplex Arterial Ultrasound +

    First-line imaging — measures aneurysm size and detects intraluminal thrombus and distal flow.

  • CT Angiography +

    Defines anatomy for surgical planning and evaluates the entire lower extremity arterial tree.

  • MRI Angiography +

    Non-contrast alternative preferred in patients with kidney disease.

TREATMENTS

RELATED CONDITIONS

FREQUENTLY ASKED QUESTIONS

  • My popliteal aneurysm is 2 cm and I have no symptoms. Should I have it repaired? +

    Yes — most vascular surgeons recommend repair of popliteal aneurysms 2 cm or larger, even when asymptomatic, because the risk of sudden limb-threatening thromboembolism is substantial. A 40% rate of limb-threatening complications in untreated symptomatic popliteal aneurysms emphasizes the importance of proactive repair.

  • If I have a popliteal aneurysm, should I be screened for aortic aneurysm? +

    Absolutely yes. The strong association between popliteal and aortic aneurysms means that any patient diagnosed with a popliteal aneurysm should undergo abdominal aortic ultrasound screening. Bilateral popliteal aneurysms are also common, so the other leg should be evaluated simultaneously.