Doppler sonography (popularly color-Doppler or colored Doppler) is an ultrasound method that uses the Doppler effect to show changes in the speed of blood flow through the blood vessels of the fetal organs.
In the first trimester, Doppler can be used to screen for chromosome disorders, to measure blood flow through the venous duct and through the right heart valve. In the second trimester, Doppler is used as a supplementary examination of the fetal heart (fetal echocardiography), looking at the direction of blood flow through the atria and ventricles as well as through the large blood vessels of the heart by measuring blood flow through them. Doppler is also routinely used to monitor flow through the umbilical artery, the middle cerebral artery and, if necessary, through other blood vessels.
