Assessment of dopperfluxometric indices of maternal-fetal structures in pregnant ewes

Abstract

The aim of this study was to evaluate the blood flow of the uterine artery, fetal aorta and umbilical artery in the physiological pregnancy of sheep by means of pulsed Doppler throughout the gestational period. Thirty Santa Inês ewes weighing between 45.4±4.3 kg and aged 2 to 5 years were selected. The evaluations were carried out weekly from the 3 rd to the 21 st gestational week. Peak systolic velocity (PSV), end diastolic velocity (EDV) and resistance index (RI) were obtained. Analysis of variance was performed, and the minimum significant comparison of means was obtained by the BH test with adjusted P<0.05. The results were expressed as mean ± standard error. For the fetal aorta, there was an increase in the EDV values and a decrease in the PSV and RI throughout pregnancy. For the uterine artery, PSV and EDV did not present significant variation, whereas the RI showed a reduction in the last week. Increased EDV values were found for the umbilical artery throughout pregnancy. For the PSV there was no significant difference, as the RI was reduced at the end of pregnancy. The results obtained are expected to contribute to a more complete understanding of the hemodynamic changes resulting from pregnancy.

Ultrasound parameters of early pregnancy and Doppler indices of blood vessels in the placenta and umbilical cord throughout the pregnancy period in sheep

“…In this study, the umbilical cord was visualized for the first time around the 33rd day of pregnancy, similar to that reported by other authors [ 4 ]. Rickard et al [ 26 ] visualized the umbilical cord already on the 23rd day of pregnancy, while Kumar et al [ 34 ] identified free movement of the umbilical cord on the 39th day of pregnancy.…”

“…In the umbilical artery, peak systolic velocity increased as pregnancy progressed and this pattern was also found in other studies in sheep [ 3 , 35 – 37 ]. In this study, as pregnancy progressed, the resistance and pulsatility indices decreased, which was also observed in other studies in sheep [ 3 , 4 , 36 – 38 ]. The end diastolic velocity was undetectable during the initial stages of pregnancy, while a gradual and progressive increase in this parameter was recorded from day 55 to the end of pregnancy.…”

“…In this study, an early detection of pregnancy was performed using select ultrasound parameters and the Doppler indices of blood flow in the placental and umbilical vessels were determined. Pregnancy was detected at a time similar to that reported by other authors who used transrectal ultrasound for the early detection of pregnancy [ 1 , 4 , 24 ]. In these studies, the most frequently assessed parameters was the size of the uterus from a cross-sectional view.…”

“…Currently, an increasingly frequently used technique in these studies is Doppler ultrasonography, which is an effective, non-invasive tool that provides information on the characteristics of vascularization and blood flow. Studies conducted so far in sheep have focused mainly on blood flow in the umbilical, uterine and fetal arteries [ 3 , 4 , 22 ]. Doppler indices obtained from these studies have provided clinically useful information.…”

“…Real-time ultrasound is one of the most important techniques for detecting and monitoring pregnancy in sheep. These studies take into account the characteristic images of the uterus, the presence of the embryo and the embryonic vesicle, the embryo's heartbeat, and the presence of placentomes [1][2][3][4]. During the detection of pregnancy using ultrasound, attention is also paid to the presence of the corpora lutea on the ovaries.…”