Testing for DVT. 1. History and physical exam. If your history and examination are suspicious that you might have a dvt, then you need a: 2. D-dimer blood test to be done. If it is very low, you don't have a dvt. If it is high you might have a DVT and you need an: 3. Ultrasound scan. This is the gold standard test. The ultimate way to check for a DVT is ultrasound.