What is the primary diagnostic/monitoring test for abdominal aortic aneurysm (AAA)?

The primary diagnostic and monitoring test for abdominal aortic aneurysm (AAA) is ultrasound. This imaging modality is favored due to its accessibility, non-invasive nature, and ability to quickly assess the size and presence of an AAA. Ultrasound can efficiently evaluate the aorta in real-time, allowing for immediate visual confirmation of the aneurysm's presence and size, which is crucial for determining the appropriate management approach.

In addition, ultrasound does not expose patients to ionizing radiation, making it a safe option for repeated evaluations, especially in patients with known aneurysms who require regular monitoring. Regular ultrasound examinations can help track any changes in the size of the aneurysm over time, which is essential for deciding if and when surgical intervention is necessary.

While CT scans and MRI can also be used for AAA, especially in specific scenarios such as surgical planning or complications, they are less commonly employed for initial diagnosis or routine monitoring due to factors like radiation exposure from CT scans and higher cost and longer duration associated with MRIs. X-ray provides limited information about the aorta and is not used effectively for diagnosing or monitoring AAA.