During a Doppler assessment, what frequency change occurs distally to a stenosis?

In a Doppler assessment, when blood flow encounters a stenosis (a narrowing of the vascular lumen), it results in a turbulent flow pattern beyond the stenosis site. This turbulence leads to a spectrum of frequency shifts, which can be detected by the Doppler ultrasound.

The turbulence generates multiple frequencies because blood is moving in a chaotic manner, with varying velocities in different directions. This characteristic is essential in vascular assessments as it provides critical information about the severity of the stenosis and the dynamics of blood flow. The presence of a turbulent spectrum indicates disturbed flow, which is a clear sign of hemodynamic changes due to the stenotic area.

Other options do not effectively describe the physiological outcomes of blood flow through a stenosis. For example, a consistent low frequency or a stable high frequency would suggest laminar flow rather than turbulent, and the absence of frequency change indicates no blockage or alteration in flow, which does not occur distal to a stenosis.