Diagnosis

Your doctor likely will start by taking your medical history and performing a physical exam. He or she may have you undergo one or more diagnostic tests and procedures to either rule out other conditions that mimic vasculitis or diagnose vasculitis. Tests and procedures might include:

• Blood tests. These tests look for signs of inflammation, such as a high level of C-reactive protein. A complete blood cell count can tell whether you have enough red blood cells. Blood tests that look for certain antibodies — such as the anti-neutrophil cytoplasmic antibody (ANCA) test — can help diagnose vasculitis.
• Imaging tests. Noninvasive imaging techniques can help determine which blood vessels and organs are affected. They can also help the doctor monitor whether you are responding to treatment. Imaging tests for vasculitis include X-rays, ultrasound, computerized tomography (CT), magnetic resonance imaging (MRI) and positron emission tomography (PET).
• X-rays of your blood vessels (angiography). During this procedure, a flexible catheter, resembling a thin straw, is inserted into a large artery or vein. A special dye is then injected into the catheter, and X-rays are taken as the dye fills the artery or vein. The outlines of your blood vessels are visible on the resulting X-rays.
• Biopsy. This is a surgical procedure in which your doctor removes a small sample of tissue from the affected area of your body. Your doctor then examines this tissue for signs of vasculitis.