The rational clinical examination. Does this patient have abdominal aortic aneurysm?

In the physical examination of abdominal aortic aneurysm (AAA), the only maneuver of demonstrated value is abdominal palpation to detect abnormal widening of the aortic pulsation. Palpation of AAA appears to be safe and has not been reported to precipitate rupture. The best evidence on the accuracy of abdominal palpation comes from 15 studies of patients not previously known to have AAA who were screened with both abdominal palpation and ultrasound. When results from these studies are pooled, the sensitivity of abdominal palpation increases significantly with AAA diameter (P<.001), ranging from 29% for AAAs of 3.0 to 3.9 cm to 50% for AAAs of 4.0 to 4.9 cm and 76% for AAAs of 5.0 cm or greater. Positive and negative likelihood ratios with 95% confidence intervals (CIs) using a cutoff point for AAAs of 3.0 cm or greater are 12.0 (95% CI, 7.4-19.5) and 0.72 (95% CI, 0.65-0.81), respectively, and for AAAs of 4.0 cm or greater are 15.6 (95% CI, 8.6-28.5) and 0.51 (95% CI, 0.38-0.67). The positive predictive value of palpation for AAA of 3.0 cm or greater in these studies was 43%. Limited data suggest that abdominal obesity decreases the sensitivity of palpation. Abdominal palpation specifically directed at measuring aortic width has moderate sensitivity for detecting an AAA that would be large enough to be referred for surgery but cannot be relied on to exclude AAA, especially if rupture is a possibility.

Duke Scholars

Author David Lee Simel Medicine, General Internal Medicine