During the process, you may hear swishing or pulse-like noises. The waves are captured and shown on a monitor as pictures or graphs. After the test, the provider will wipe the gel off your skin. The exam takes between 30 and 60 minutes to complete. You can expect to pay about $150 to $300 for this test. Some insurance companies require you to pay out of pocket for this test but others cover it as part of your coverage. If you have health insurance, ask your doctor what kind of coverage you have for these tests. Sometimes there are restrictions on who can order the test or where it can be done. Your doctor should be able to tell you more about any such limitations. The Doppler test is used to measure the speed of blood flowing through vessels. It produces a graph showing how fast the blood flows against a baseline. This baseline can be seen in the form of a color scale that ranges from green to red. When you first see the monitor after the test has been completed, the picture will appear black because there are no waves yet to capture. As more measurements are taken, the machine produces a color-coded image of blood flow in the arteries. You can then see where there might be problems by looking at areas of the image that are in red or yellow.