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Obstetrical Doppler: the evidence today

Centuries ago, the Austrian physicist Christian Doppler (Salzburg 1803–Venice 1853) described the fact that, when an energy encounters a moving object, the reflected wave changes its frequency, increasing or decreasing it according to the direction of the movement of the target object. This phenomenon is called the Doppler effect. More than a century later, in 1977, using blood cells as a moving target, Fitzgerald and Drumm [6] first described the application of the Doppler effect for measuring blood flow velocity in umbilical arteries in humans. It became clear that this methodology was offering the possibility of assessing hemodynamics noninvasively in the fetouteroplacental circulation. The era of obstetric Doppler had begun.