Automatic and manual Doppler velocimetry measurements of the uterine artery in pregnant ewes.

We aimed to compare measurements of speed and blood flow parameters obtained manually and automatically in the uterine arteries of pregnant ewes. Eighteen Santa Inês ewes, confirmed to be pregnant, were followed every 2 weeks until parturition. The systolic peak (PS), end diastolic velocity (ED), maximum and average speed in the cardiac cycle (TAMAX and TAMEAN, respectively), pulsatility index (PI), resistance index (RI) and the systole/diastole (S/D) ratio and body flow volume (BFV) was measured. We began the wave evaluation automatically, then the observer manually marked the beginning and end of the wave. To determine the differences between manual and automatic methods, a t-test was used for each of the study variables (PS, ED, TAMAX, TAMEAN, PI, RI, S/D, and BFV), with p<0.05 considered significant. Both methods were found to be effective for producing estimates for the variables analyzed. With the exception of the IP, IR and S/D (p<0.05), no significant differences were found between the methods. The manual method underestimated the PI (1.00±0.21×1.04±0.20), S/D (2.51±0.43×2.40±0.44) and RI (0.57±0.07×0.59±0.07) compared with the automatic method (p<0.05). The weakest correlations between methods were identified for the PI, RI and S/D variables (p<0.001). Manual evaluation allowed more accurate identification of the beginning and end of the systole and diastole, which may influence the outcome of some variables.

Transrectal Doppler sonography of uterine blood flow in ewes during pregnancy.

In sheep, there is a lack of information on the behaviour of hemodynamic indices and parameters of blood flow velocity of the uterine artery during pregnancy, making it impossible to determine the real meaning of the values found and their probable relevance in normal physiological or pathological states. The objective of the present study was to evaluate the blood flow velocity parameters and hemodynamic indices of the uterine artery in ewes (18) during pregnancy (33). Based on non-invasive colour Doppler sonography, we evaluated the peak systolic velocity (PS), end diastolic velocity (ED), time-averaged maximum and minimum velocity in a cardiac cycle (TAMAX and TAMEAN), pulsatility index (PI), resistance index (RI), systolic/diastolic ratio (S/D), heart rate (HR), arterial diameter (AD) and the blood flow volume (BFV). Examinations started on day 28 and continued at two-week intervals until parturition. The Doppler parameters and the diameter of the uterine artery underwent significant changes during pregnancy. In the evaluated animals, indices related to resistance of the uterine artery, namely the impedance of blood flow, decreased throughout the initial, middle and late stages of gestation (PI: 1.15, 1.04, 0.97; RI: 0.61, 0.59, 0.57; S/D: 2.68, 2.52, 2.39, respectively) (p < 0.05). In contrast, the contents related to higher uterine irrigation increased during gestation (PS, ED, TAMAX, TAMEAN, HR, AD and BFV) (p < 0.05). No differences were found between the means of the variables in relation to the right and left uterine arteries and between single and multiple pregnancies in the hemodynamic indices. The present study is the first to demonstrate changes in uterine hemodynamics throughout pregnancy in sheep.