Fig. 1
From: Doppler evaluation of maternal vessels in normal gestation and threatened abortion in canines
Pulsed wave Doppler image of uteroplacental arteries during 40 to 50 days of gestation in threatened abortion cases. The wave form of the uteroplacental arteries in the threatened abortion cases was quite different than the normal gestation. It was observed that during 40–50 days a systolic peak was followed by full diastole, with broadening and progressive flattening of the diastolic upstroke. This culminated in a monophasic wave with little oscillation during diastole. This wave morphology might suggest vascular pathology due to the placentitis