From the Guidelines
The physical examination for abdominal aortic aneurysm (AAA) involves systematic palpation of the abdomen with the patient in a supine position with knees slightly flexed to relax the abdominal muscles, as recommended by the most recent guidelines 1. The examination should begin by placing both hands on the midline of the abdomen at the level of the umbilicus, applying gentle but firm pressure to feel for a pulsatile mass.
- Palpate from the xiphoid process down to the umbilicus, noting any widening or abnormal pulsation of the aorta.
- An AAA typically presents as a pulsatile, expansile mass in the mid-abdomen, usually measuring greater than 3 cm in diameter.
- Auscultation over the aorta may reveal a bruit if turbulent blood flow is present. The sensitivity of physical examination decreases significantly with obesity, and smaller aneurysms (less than 5 cm) may be difficult to detect by palpation alone 1. While examining, note that the normal aorta is approximately 2 cm in diameter; anything larger may indicate an aneurysm. Remember that physical examination alone is insufficient for diagnosis or exclusion of AAA, particularly for smaller aneurysms, and should be followed by imaging studies such as ultrasound, CT, or MRI if an AAA is suspected based on risk factors or examination findings 1. It is essential to consider the patient's risk factors, such as age, sex, smoking history, and family history of AAA, when interpreting the physical examination findings 1. In cases where an AAA is suspected, imaging studies should be performed to confirm the diagnosis and determine the size and extent of the aneurysm 1.
From the Research
Physical Exam Procedure for Abdominal Aortic Aneurysm (AAA)
The physical exam procedure for AAA primarily involves abdominal palpation to detect abnormal widening of the aortic pulsation.
- The sensitivity of abdominal palpation increases significantly with AAA diameter 2.
- Palpation of AAA appears to be safe and has not been reported to precipitate rupture 2.
- Abdominal obesity decreases the sensitivity of palpation 3, 2.
Factors Affecting Physical Exam Procedure
Several factors can affect the physical exam procedure for AAA, including:
- AAA size: Larger AAAs are more easily detectable by palpation 2.
- Patient body mass index (BMI): Obese patients have a lower detection rate of AAAs by physical examination 3.
- Operator skill and experience: The accuracy of abdominal palpation may vary depending on the operator's skill and experience.
Limitations of Physical Exam Procedure
The physical exam procedure for AAA has some limitations, including:
- Limited sensitivity: Abdominal palpation has moderate sensitivity for detecting large AAAs but cannot be relied on to exclude AAA, especially if rupture is a possibility 2.
- Operator-dependent: The accuracy of abdominal palpation depends on the operator's skill and experience.
- Not a substitute for imaging: Physical examination should not be relied upon as the sole means of diagnosis, and imaging studies such as ultrasound or CT scans should be used to confirm the diagnosis 4, 5.