A 78 year old woman has a pulsatile mass in her mid abdomen. You wonder whether it is an abdominal aortic aneurysm.
Describe and interpret these scans
Image 1: Transverse view abdominal aorta with colour Doppler. There is a 65mm abdominal aortic aneurysm.
Abdominal aortic aneurysm (AAA)
Blood flowing through a dilated artery often spirals as it swirls through the dilated passage.
Colour Doppler interrogation shows the flow rushing towards the probe up one wall (red) and then swirling away down the other wall (blue). This can create a Yin and Yang appearance.
The Yin and Yang sign is most typical with flow through a pseudoaneurysm but can also be seen in other aneurysms.