Decreasing peripheral resistance during pregnancy monitored at the cubital artery

Background During the physiological course of pregnancy maternal peripheral vascular resistance decreases. Using the Doppler technique, the decreasing resistance and disappearance of the early diastolic notch in the arterial uterine perfusion can be observed. These changes in the Doppler flow velocity wave form are caused by the trophoblast invasion in which the spiral arteries loose their musculoelastic structure of the arterial wall. The aim of this study was to investigate whether maternal systemic alteration in the Doppler flow velocity waveform and Pulsatility Index (PI) could be monitored at the cubital artery during normal pregnancy. Methods and results Forty-five patients were investigated in a prospective study in 4-6-week intervals for Dopplersonographic evaluation of the two uterine arteries and the right cubital artery; 20 of the patients were also investigated after delivery. The presence or absence of the early diastolic reverse flow of the cubital artery was analyzed. Furthermore, the PI was calculated for all vessels. With increasing duration of gestation, the reverse flow of the cubital artery disappeared. During the course of gestation a significant decrease in the PI of the cubital artery was observed in addition to a significantly decreased PI of the uterine arteries. The PI of the placental and nonplacental uterine arteries showed a significant correlation to the PI of the cubital artery. Conclusions This study demonstrates systemical changes in arterial resistance correlating to those of the uterine arteries during the course of physiological pregnancy.