What is the ultrasound procedure for diagnosing an abdominal aortic aneurysm (AAA)?

From the Guidelines

Ultrasound is the recommended initial imaging test for detecting and monitoring abdominal aortic aneurysms (AAAs) due to its safety, accuracy, and cost-effectiveness, as supported by the most recent guidelines 1.

Key Points:

• The patient should fast for 8-12 hours before the exam to reduce intestinal gas that could interfere with image quality.
• During the procedure, the patient lies on their back while a sonographer applies gel to the abdomen and moves a handheld transducer across the skin.
• The exam typically takes 30-45 minutes and focuses on measuring the aorta's diameter, with an aneurysm diagnosed when the diameter exceeds 3 cm.
• The sonographer will assess the aneurysm's size, location, shape, and presence of blood clots or dissection.
• Regular surveillance ultrasounds are recommended for aneurysms smaller than 5.5 cm, typically every 6-12 months depending on size, while those 5.5 cm or larger generally warrant surgical consultation as they carry higher rupture risk, as stated in the 2022 ACC/AHA guideline for the diagnosis and management of aortic disease 1.

Surveillance Intervals:

• For AAAs of 3.0 cm to 3.9 cm, longer surveillance imaging intervals have been shown to be safe, with recommendations for surveillance every 3-5 years 1.
• For AAAs of 4.0 cm to 4.9 cm, annual surveillance ultrasound is recommended due to higher rates of aortic growth 1.
• For AAAs of 5.0 cm or larger in men and 4.5 cm or larger in women, the screening interval is shortened to every 6 months given the potential of larger aneurysms to grow more rapidly and reach the thresholds for intervention 1.

From the Research

Ultrasound Procedure for Abdominal Aortic Aneurysm

• The use of ultrasound in monitoring abdominal aortic aneurysm (AAA) growth is supported by various studies 2, 3, 4.
• A study published in 2008 found that patients with AAA undergoing ultrasonographic surveillance had a decreased linear aneurysm growth rate when treated with statins, although this difference did not reach statistical significance 2.
• The Society for Vascular Surgery practice guidelines recommend surveillance imaging at 12-month intervals for patients with an AAA of 4.0 to 4.9 cm in diameter, which can be done using ultrasound 3.
• A study published in 2015 found that abdominal aortic aneurysm screening rates using ultrasound increased from 3.6% in 2007 to 9.2% in 2012, although screening rates remain below 50% 4.
• The US Preventive Services Task Force (USPSTF) guidelines recommend one-time abdominal aortic aneurysm ultrasound screening for men aged 65 to 75 years who ever smoked 4.

Surveillance and Screening

• Regular surveillance using ultrasound is essential for monitoring AAA growth and preventing rupture 2, 3.
• Screening for abdominal aortic aneurysms can be done intentionally with ultrasound or incidentally with other abdominal imaging modalities 4.
• Physician characteristics, such as female sex, specialty, and location, are associated with higher screening rates 4.

Treatment and Management

• The use of beta-blockers during aortic aneurysm repair is a topic of debate, with some studies suggesting a decrease in mortality following open AAA repair 5.
• The Society for Vascular Surgery practice guidelines provide recommendations for the treatment and management of patients with AAA, including the use of endovascular repair and open surgical repair 3.