Several options. There are several options for the detection of a blood clot. A blood test for d-dimer may determine whether there is a clot. If this level is elevated, the physician may move to ultrasound (doppler). The doppler ultrasound is still the gold standard to detect clots, especially in the vessels of the legs. If there is a suspected pulmonary embolism, you will be sent for a ct scan of the chest.
Ultrasound. Finding out what has happened is the first step. By knowing what risk factors for a blood clot you have helps in interpreting whether you need a blood test or not. If your risk factors indicate that you need a blood test , then a d-dimer is done. Unfortunately, lots of things can make you d-dminer high but if your results indicate a strong possibility for a blood clot, an unltrasound is done.
Ultrasound. They might order an ultrasound.