Evaluate blood flow after a stroke or other condition that might be caused by a problem with blood flow. Evaluation of a stroke can be done through a technique called transcranial Doppler (TCD) ultrasound.
Map veins that may be used for blood vessel grafts. It also can check the condition of grafts used to bypass blockage in an arm or leg.
Find out the amount of blood flow to a transplanted kidney or liver.
Monitor the flow of blood following blood vessel surgery.
Find out the presence, amount, and location of arterial plaque. Plaque in the carotid arteries can reduce blood flow to the brain and may increase the risk of stroke.
Guide treatment such as laser or radiofrequency ablation of abnormal veins.
Check the health of a fetus. Blood flow in the umbilical cord, through the placenta, or in the heart and brain of the fetus may be checked. This test can show if the fetus is getting enough oxygen and nutrients. Doppler ultrasound may be used to guide decisions during pregnancy when:
The fetus is smaller than normal for his or her gestational age (fetal growth restriction). Blood flow through the large blood vessel in the umbilical cord (the umbilical artery) can be looked at.
Rh sensitization has occurred. Blood flow through a blood vessel in the brain (the middle cerebral artery, or MCA) can be used to monitor fetal health.
The mother has other problems, such as preeclampsia or sickle cell disease.
A transcranial Doppler (TCD) ultrasound may be used in children with sickle cell disease to evaluate their risk of stroke. In adults, TCD can be used to evaluate blood flow in the brain.
How To Prepare
You may need to stop using products that contain nicotine (cigarettes, chewing tobacco) for 30 minutes to 2 hours before the test. Nicotine causes blood vessels to constrict and may give false results.