Marked change in Doppler waveform: report of two cases of subcutaneous hematoma.

We present two cases of subcutaneous hematoma in which color Doppler US revealed colored areas under probe compression, and Doppler waveforms obtained from these areas changed rapidly (from a constant flow to a pulsatile flow, and from a high-velocity flow to a slow-velocity flow) according to the degree of probe compression. In our cases, a sufficient number of blood cells within the lesion moving under probe compression was thought to give rise to Doppler signals and changes in Doppler waveforms.