How is deep vein thrombosis diagnosed?

If visible symptoms are present, your doctor will conduct a physical exam, inspecting the affected area by sight and touch. If you have risk factors for DVT, but no visible symptoms (which occurs in about 50 percent of people with DVT), your doctor may perform one of a few different tests to get a picture of your veins. In an ultrasound exam, your doctor will pass a wand, which emits sound waves and catches their reflections to create a moving picture of the inside of your veins, over the affected area. In a CT or MRI scan, your doctor will scan the affected area with an x-ray machine hooked up to a computer to create a series of images. Venography, in which your doctor injects a dye into your veins so that they will show up more clearly on an x-ray, is used less often. In addition to or instead of these imaging tests, your doctor may draw blood and test it for the presence of D dimer, a substance produced by blood clots.