Q: 64 year male presented to ER with abdominal pain. Patient is send to CT scan. You received call from radiologist that patient has a "Crescent sign". What does it means?
Answer: Impending AAA rupture
If a hyper-dense crescent can be appreciated within the thrombus of AAA, it implies probable impending AAA rupture. It means a loss in the ability of the thrombus to protect the aneurysm from rupture.