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Shifting Dullness Test
Definition: A pathological dilation of the popliteal artery due to a weakness or defect in the arterial wall or predisposed by injury.
Causes: The popliteal artery, a continuation of the femoral artery is common side of peripheral aneurisms. Peripheral aneurisms are more common in males especially over the age of 55. It is often predisposed by atherosclerotic changes to the vessels, other vascular or collagen disease. In some cases (20%) the patient may also have a history of abdominal aortic aneurism.
Examination: If the popliteal aneurism is large it may be visible as a mass in the popliteal fossa. Palpating the popliteal fossa may reveal a pulsating artery which is abnormally pulsatile. More accurate diagnostic methods include duplex ultrasonography, A non pulsating popliteal mass may be a Baker's cyst or inflamed knee bursa.