What is a Doppler Test?

A Doppler test is a non-invasive medical test used to examine blood flow through major arteries. Sometimes called a Doppler ultrasound, the test helps doctors identify blockages than can lead to health complications, such as a stroke. Doppler imaging also helps doctors diagnose conditions such as arterial occlusion, blood clots, tumors and problematic issues with arteries and veins.

A transducer, which is a handheld device, is used to conduct the test. Coated with water-soluble, Doppler gel, the transducer is placed over the skin, above a blood vessel. It emits high-frequency sound waves which bounce off the veins or arteries being tested. If the speed of the blood flow changes, the sound frequency will change noticeably. Much like the way a radar gun measures driving speed, the Doppler test measures speed and efficiency of blood flow. If blood flow is smooth and uninterrupted, the test is normal. If a blockage is present, the Doppler test results will return an abnormal report.

Abnormal results can indicate a variety of problems. Some potential issues include arterial blockage, closed veins, or tumors. A physician is required to interpret Doppler test results.

The Doppler test is also used during pregnancy to monitor blood flow. Proper flow from the mother to the baby is critical to the health of the baby. The test also allow's physicians to monitor and assess the baby's heartbeat. The machine can actually be rented by expecting parents, allowing them to perform the Doppler test at home and listen to their baby anytime.

Sometimes a color Doppler ultrasound is performed. This version of the test converts the sound wave results into colored results. Colored tests are sometimes used to identify cancerous tumors which are identified because they generally show an increase in blood flow. While doctors are skilled in reading both types of tests, the color version is typically easier to read.

Doppler tests requires almost no preparation on the patient's part. The patient simply must remove any clothing from the area to be tested. Since nicotine can affect Doppler test results — because it causes veins to constrict — patients may be required to refrain from smoking for a period before testing. Being a non-invasive test, the Doppler test causes little to no discomfort, and there is little to no risk associated with the procedure.