Most diagnostic testing for vein problems is painless and non-invasive, meaning no incisions are needed. Typically, the doctor will first take a detailed medical history and physically examine your legs while you're standing up. However, a visual and manual exam may not reveal all problems, since the source of the problem could lie deep in the leg. For a better evaluation, doctors typically use a hand-held device called a Doppler (DAWP-luhr) probe. Doppler ultrasound sends back sound waves that help determine whether blood in the veins is flowing properly up the leg, or whether it's leaking backward, a condition referred to as reflux. In the majority of cases, ultrasound is the only test required. However, if further investigation is needed, a test called “air-plethysmography” (pleth-ihz-MAW-gruh-fee) may be used. This test tells doctors how much blood is flowing backward and how well the calf muscle is working to help pump blood upwards. The results provide an estimate of blood pressure in the leg. Another sophisticated test is color duplex ultrasound imaging. This non-invasive procedure can be teamed with Doppler ultrasound to allow doctors to see the blood flow inside the leg, including the location and size of the diseased veins, without the need to inject contrast dyes.