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An aneurysm is an abnormal widening or ballooning in a blood vessel, usually an artery, caused by weakness in the wall of that blood vessel.


  • An aneurysm is an abnormal widening or ballooning in a blood vessel, usually an artery, caused by weakness in the wall of that blood vessel.
  • The most common types of aneurysms are: aortic aneurysm, cerebral aneurysm and peripheral aneurysm.
  • Aneurysms can sometimes be managed medically, but the definitive treatment is surgical.

Alternative names

Aortic aneurysm, cerebral aneurysm, peripheral aneurysm

What is an aneurysm?

An aneurysm is an abnormal widening or ballooning in a blood vessel, usually n artery, caused by weakness in the wall of that blood vessel.
The most common types of aneurysms are:

  • Aortic aneurysms – there are two types of aortic aneurysms: thoracic and abdominal aorta. The more common of the two is an abdominal aorta aneurysm. An abdominal aneurysm is the localised dilation of the part of the aorta situated in the abdomen.
  • Cerebral aneurysm – a cerebral aneurysm occurs in the wall of a vein or artery located in the brain. If it ruptures it can cause a stroke.
  • Peripheral aneurysms – these occur in arteries other than the aorta. Common locations include the artery that runs down the back of the thigh behind the knee, the main artery in the groin area and the main artery in the neck. These are less likely to rupture but can cause blood clots. If a blood clot breaks away it can block blood flow in a part of the artery further away.

What causes it?

The most common disease associated with the formation of aneurysms is atherosclerosis, which is a vascular disease (a disease of the blood vessel). Other, much less common diseases that may lead to aneurysms are arteritis (inflammation of the arteries), syphilis and congenital connective tissue disorders such as Marfan’s syndrome. These may result in weakened areas on the blood vessel wall.

Constant high blood pressure can cause an aneurysm to form where a blood vessel wall has a weak spot.

What are the symptoms?

Most aortic aneurysms are small and do not produce any symptoms. Some aneurysms can cause a small pulsating mass near the navel. Growing aneurysms can become tender and may cause pain in the lower back or abdomen.
A large aneurysm may apply pressure on the abdominal organs surrounding it and may even cause tissue damage to these organs, which is often painful.
A cerebral aneurysm may cause the following symptoms: a droopy eyelid, sudden severe headache, intense neck stiffness, double-vision, nausea and vomiting.
Symptoms associated with peripheral aneurysms are: a throbbing lump felt in the neck, arm or leg, pain in the leg or arm, painful sores on the toes or fingers, and gangrene.

How is it diagnosed?

Since most aneurysms show no symptoms they are usually detected during a routine physical examination.
If you have an abdominal aneurysm the doctor will feel a pulsating mass in the abdomen.
Other tests used for diagnosis include: ultrasound, CT scan, chest X-ray, MRI, angiograph and an aortagram.

How is it treated?

The goal of treatment is to prevent rupture, which carries a high mortality rate.
The risk of rupture is related to the size of the aneurysm and the rate at which it grows.
Aortic aneurysms that are small (less than 5cm across), found early and cause no symptoms can be managed by ultrasound monitoring at regular six monthly intervals. Blood pressure must be kept low to avoid further stretching of the aneurysm, and smoking must stop. For aneurysms >5cm, or those growing faster than 0.5cm over six months, surgery is recommended. The most common form of surgery involves removing the diseased part of the aorta and replacing it with a synthetic graft.
For patients who are not suitable for surgery an endovascular stent can be used. This involves placing a stent inside the aorta. Blood flows through the stent and not the diseased aorta. The risk of clot formation is reduced.
Emergency treatment for patients with a ruptured cerebral aneurysm generally includes restoring deteriorating respiration and reducing intra-cranial pressure. Surgery is usually performed as soon as possible to clip the ruptured aneurysm in order to reduce the risk of re-bleeding.

Patients with a ruptured aortic aneurysm have a high mortality rate: about 50% survive long enough to reach the operating theatre, of whom 50% do not survive the emergency surgery.
In patients for whom surgery is considered too risky, microcoil thrombosis or balloon embolisation may be performed. Other treatments may include bed rest, medication or anti-hypertensive/hypovolaemic therapy.
Peripheral aneurysms seldom rupture. Treatment will depend on the symptoms present, the location and whether blood flow is blocked.

What is the prognosis?

If detected early, aneurysms can be treated successfully with medication and surgery.

When to call your doctor

  • If there is a pulsating mass in your abdomen or any other part of your body
  • If there are signs of atherosclerosis such as heart disease and high blood pressure
  • If your experience lower back pain, especially if this is a new symptom

How can it be prevented?

    • Control high blood pressure
    • Control high cholesterol
    • Stop smoking
    • Exercise regularly
    • Eat a low-fat, low cholesterol diet to prevent a build-up of plaque in the arteries

In the interest of our patients, in accordance with SA law and our commitment to expertise, Mediclinic cannot subscribe to the practice of online diagnosis. Please consult a medical professional for specific medical advice. If you have any major concerns, please see your doctor for an assessment. If you have any cause for concern, your GP will be able to direct you to the appropriate specialists.