The Abdominal Aorta
The aorta is the body’s largest blood vessel, carrying oxygen-rich blood from the heart to the rest of the body. The abdominal aorta begins at the diaphragm (where the chest ends) and continues down through the abdomen, supplying blood to vital organs such as the kidneys, intestines, and lower limbs. It gradually divides into smaller arteries that supply blood to the legs and pelvis. An aneurysm is a bulge or ballooning in the wall of an artery, which causes the artery to stretch and weaken. While aneurysms can develop in any artery, they are most common in the abdominal aorta, an abdominal aortic aneurysm (AAA).
Understanding Abdominal Aortic Aneurysms
Symptoms
Most AAAs develop slowly over many years and often do not cause any symptoms, so people may be unaware they have one. If an aneurysm grows large, the wall becomes weaker and there is an increased risk it could rupture, which is a serious medical emergency. When symptoms do occur, they may include:, A pulsating feeling or a throbbing sensation in the tummy, Deep, constant pain in the abdomen or lower back, Pain radiating to the side or legs If an aneurysm ruptures, it causes sudden, severe abdominal or back pain, dizziness, nausea, or loss of consciousness. This is a medical emergency, and immediate hospital care is needed.
Causes and Risk Factors
The exact cause of an abdominal aortic aneurysm (AAA) is not fully understood. While the ultimate cause remains unclear, certain factors are known to increase the risk of developing an AAA.
- Demographic Factors Age: More common in people over 65. Sex: Men are about six times more likely than women to develop an AAA. Family history: Having a close relative with an AAA increases risk.
- Lifestyle Factors Smoking: Damages the aortic wall, promotes atherosclerosis, and increases oxidative stress, making the aorta more prone to aneurysm. High blood pressure (hypertension): Increases stress on the artery walls.
- Medical Conditions Atherosclerosis: Build up of fatty deposits weakens the arterial wall. Genetic/connective tissue disorders: Certain inherited conditions (e.g., Marfan syndrome, Ehlers-Danlos syndrome) can increase risk.
Diagnosing an AAA
Many abdominal aortic aneurysms do not cause symptoms and are found by chance during routine scans.
- Screening In the UK, men aged 65 or over are invited for a one-time ultrasound scan to check for an AAA. This painless scan measures the size of the abdominal aorta and can detect aneurysms early. Screening is less commonly offered to women, but it may be considered if there are significant risk factors.
- Ultrasound Ultrasound is also used outside of screening to investigate symptoms (such as abdominal or back pain) or to monitor a known aneurysm over time. These scans may be repeated at intervals to track the size of the aneurysm and help doctors decide if treatment is needed.
- CT Scan Provides detailed images and is used if surgery is being considered or if the aneurysm is large.
Treatment Options
When you have an AAA screening ultrasound, the results are based on the diameter of your abdominal aorta. Different sizes guide what happens next:
- Normal aorta (less than 3.0 cm) No aneurysm is present. You are usually discharged from screening, but it’s still important to maintain a healthy lifestyle.
- Small aneurysm (3.1 cm, 4.4 cm) The aorta is slightly enlarged. You will usually be invited for regular monitoring with ultrasound every 12 months to check for growth.
- Medium aneurysm (4.5 cm, 5.4 cm) The aorta is moderately enlarged. Ultrasound checks are typically every 3 to 6 months, and your doctor may discuss treatment options if it continues to grow.
- Large aneurysm (5.5 cm or more, or growing quickly) The risk of rupture is higher. You will usually be referred to a specialist vascular surgeon to discuss surgical repair.
Conservative Management
Most small AAAs (less than 5.5 cm) are monitored regularly with ultrasound scans to check if the aneurysm is getting larger. Lifestyle measures are recommended to reduce cardiovascular risk, such as:
-Stopping smoking -Controlling blood pressure and cholesterol -Maintaining a healthy weight -Regular exercise
Most AAAs detected through screening are small and do not require immediate surgery. Regular monitoring allows early detection of growth and timely intervention if needed.
Surgical Repair
Surgery is usually considered for AAAs that are large (5.5 cm or more) or growing quickly, due to the higher risk of rupture. Two main procedures are used:
-Open Surgery - The surgeon makes an incision in the abdomen to remove the aneurysm and replace it with a synthetic graft. -Endovascular aneurysm repair (EVAR) - A less invasive procedure where a stent graft is inserted through the arteries to reinforce the weakened section of the aorta.
Your vascular specialist will discuss which approach is safest based on your overall health and the anatomy of the aneurysm.