An endoleak is the leaking of blood outside a stent graft and within an aneurysm sac. It’s a common complication of endovascular aneurysm repair (EVAR). There are five types of an endoleak. Type 2 is the most common. Types 3 and 4 are less common due to new graft technology. Endoleaks may require endovascular treatment methods to prevent aneurysm rupture.


What is an endoleak?

An endoleak is a common complication of endovascular procedures that repair aortic aneurysms. It involves the flow of blood within an aneurysm sac after it’s been sealed. Endoleaks occur for a number of reasons. Some result from the graft itself, while others result from vessels that arise off the aneurysm sac.

Normally after aneurysm repair, your blood flows through a new artery lining called a stent graft. The stent graft prevents blood from flowing into the damaged part of your artery (the aneurysm sac). Blood shouldn’t flow outside of your stent graft within the aneurysm sac. If that happens, it’s called an endoleak.

Endoleaks that happen within 30 days of an endovascular repair procedure are called “early endoleaks.” Endoleaks that form more than 30 days after a procedure are called “secondary endoleaks” or “late endoleaks.”


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How common are endoleaks?

About 1 in 4 people who have endovascular aneurysm repair procedures experience an endoleak. Endoleaks happen after endovascular aneurysm repair (EVAR) and thoracic endovascular aneurysm repair (TEVAR).

Is an endoleak serious?

Some endoleaks are harmless and go away on their own. In some cases, your healthcare provider may choose to monitor your condition. Other cases are serious and require treatment in order to keep the aneurysm sealed. It depends on the endoleak type and location.


What are the endoleak types?

There are five endoleak types. Each type has a different cause. Some endoleak types are becoming less common, as stent graft technology improves. Type 2 endoleaks are the most common. Types 1 and 3 are the most dangerous because they have the highest risk of rupture.

Type 1 endoleak

A type 1 endoleak happens when the stent graft isn’t properly attached to your artery wall. Blood leaks around the top or bottom of your stent graft. Type 1 endoleaks are serious and usually need treatment immediately. They have a higher risk of rupturing than other endoleak types.

Type 2 endoleak

Type 2 endoleaks are the most common type overall. They’re more common after EVAR than TEVAR. These leaks happen when blood flows into the aneurysm sac from branches of your aorta or other blood vessels treated with a stent.

Type 2 endoleaks are often diagnosed within 30 days of your endovascular repair procedure. But they can also appear as late endoleaks. About 40% of type 2 endoleaks are diagnosed after 30 days. And 8% are diagnosed more than one year after the procedure.

Type 2 endoleaks are often harmless. They usually go away without treatment within six months. If it doesn’t go away and the aneurysm sac remains stable, your healthcare provider can monitor it. Occasionally, over time, a type 2 endoleak can cause changes to the aneurysm sac. This can lead to a type 1 or type 3 endoleak. These are much more serious and need treatment. You may need treatment if the aneurysm size grows by over 5 millimeters. If left untreated, rupture of the aneurysm may occur.

Type 3 endoleak

Type 3 endoleaks happen when overlapping parts of your stent graft become separated. Like Type 1 endoleaks, rupture is a concern. So, prompt treatment is important. Due to advances in device design, Type 3 endoleaks are less common today.

Type 4 endoleak

Type 4 endoleaks happen when blood flows through the pores of your stent graft. This is a rare cause of graft complications.

Type 5 endoleak

A type 5 endoleak is called an “endotension.” This happens when the aneurysm sac expands even though imaging tests show no signs of an endoleak.

Symptoms and Causes

What are the symptoms of an endoleak?

Usually, an endoleak doesn’t cause any symptoms that you’ll notice. Endoleaks are discovered through imaging tests on the day of your procedure and at follow-up appointments. This is why monitoring is so important. An endoleak that leads to an aneurysm rupture is a medical emergency. Call 911 if you have the following symptoms of an aneurysm rupture:


Diagnosis and Tests

How is an endoleak diagnosed?

Endoleaks are diagnosed through imaging tests. These tests happen during and after your endovascular aneurysm repair procedure. They’re commonly diagnosed on the same day of your procedure or within 30 days. But they can also appear within 12 months or even later. That’s why it’s important to keep all your follow-up appointments.

Tests to diagnose an endoleak

Tests used to diagnose endoleaks during and after your procedure include:

These tests show if your procedure was successful and if the stent graft is in place. They also show any leaks around the stent.

You’ll also have imaging tests in the months and years after your procedure. Your healthcare provider will talk with you about these tests and how often you’ll need them. But they’re essential for catching any secondary endoleaks so you can get treatment if needed.

Management and Treatment

What are the treatments for endoleaks?

Your medical team will tailor your endoleak treatment to your individual needs. Endoleak management is different from person to person. Your anatomy (like the length of your neck) and the endoleak type and the location all play a role. In general, endoleak treatment involves three main options: observation, endovascular treatment and/or open surgery.


Your healthcare provider may use “watchful waiting” to see if a type 2 endoleak goes away on its own. This can happen if the connecting blood vessels clot off (stop sending blood to the aneurysm sac). But if the endoleak causes the aneurysm sac to get bigger, then you’ll need treatment to prevent a rupture.

Endovascular treatment

Your endovascular surgeon can perform minimally invasive procedures to fix endoleaks. These may include:

  • Embolizing (blocking) the feeding arteries that go into the aneurysm.
  • Extending the stented area of your aorta by placing stents beyond the part of the graft that’s leaking.
  • Examining the aneurysm and using glue-like materials to seal the aneurysm sac.


Surgery is usually the last resort if endovascular treatments can’t be used. This is rare.

Outlook / Prognosis

What can I expect if I have an endoleak?

An endoleak often needs no treatment. If it does need treatment, there are many minimally invasive options. These endovascular procedures show high success rates. Plus, new technologies continue to provide better stent grafts that reduce the risk for endoleaks.

If you have an endoleak, your healthcare provider will discuss your treatment options with you. You’ll need routine follow-up appointments even after the endoleak is gone. It’s important to watch for any future problems with your stent graft so they can be treated right away.

Living With

When should I see my healthcare provider?

Keep all of your follow-up appointments after your EVAR or TEVAR procedure. Your healthcare provider will let you know how often you need to get imaging tests.

What questions should I ask my doctor?

After your EVAR or TEVAR procedure, ask your healthcare provider about the risk for complications. You can also talk about follow-ups and which imaging tests to expect. Some questions might include:

  • What are possible complications from this procedure?
  • What’s my risk for an endoleak?
  • How often should I come in for follow-ups?
  • What tests will I need?
  • What lifestyle changes can I make to help my heart health?

A note from Cleveland Clinic

Endoleaks are a complication from endovascular aneurysm repair procedures. You may not need any treatment. But if you do, your healthcare provider will work with you and discuss your treatment options. It’s normal to have complications after a life-saving procedure like an aneurysm repair. The benefits outweigh the risk of complications. But if you’re feeling tired or overwhelmed, it’s OK. Many people are in the same boat. Talk with your healthcare provider about ways to manage the stress of recovery.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 06/06/2022.

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