Making the diagnosis when the patient has 'blue toes'.

Painful "blue toes" describes a physical sign whose meaning may be discovered through a carefully taken history, physical, and laboratory evaluation. Accurate diagnosis is important, because therapy for one specific condition may be contraindicated for another. When embolism is suspected, ultrasound examination of the heart, aorta, and periphery may be useful prior to angiography in order to avoid exacerbation of cholesterol crystal embolization. Transesophageal echocardiography or MRI may be needed to exclude a thoracic aortic source. The differential diagnosis can be divided into three categories: emboli from the cardiac and arterial system, acquired hypercoagulability disorders, and syndromes that lead to peripheral vascular pathology. A clinical approach to the evaluation of patients is presented, with case reports.