Doppler evaluation of umbilical artery during normal gestation in sheep

Prenatal Echo-Sonographic Parameters in Fetuses Wrapped with the Umbilical Cord in the Third Trimester of Pregnancy

This study constitutes a description of prenatal echo-sonographic parameters in fetuses wrapped with the umbilical cord in the third trimester of pregnancy and demonstrates the practical importance of the umbilical cord collision. Echocardiographic examinations were performed within 6 months, and a group of patients in the third trimester with a mean age of 28.1 ± 0.79 weeks of gestation (p = 0.075) was distinguished. The group included 46 fetuses from single pregnancies with the umbilical cord around the fetal neck and 70 fetuses without the umbilical cord around the fetal neck. The course of the umbilical cord coiling around the fetal neck was recorded by color Doppler. We also conducted a follow-up with the newborns. In the study group, there was an elevated peak systolic velocity of the umbilical artery (UMB PSV) at a level of 44.17 cm/s vs. 38.90 cm/s in the control group (p = 0.004), and caesarean sections were significantly more frequent (54.5% vs. 31.4%). The persistence of the nuchal cord during delivery was observed in 37% of newborns in the study group, while the occurrence of umbilical wrapping during delivery was found in 18.6% of newborns in the control group (p = 0.027). In the studied cases, caesarean sections were 2.62 times more frequent (OR = 2.62), whereas nuchal cords during delivery were 2.57 times more often observed (OR = 2.57). Fetal umbilical cord wrapping in the third trimester of pregnancy does not have a significant hemodynamic impact; however, the UMB PSV might be slightly elevated in this group, and the frequency of umbilical cord collision during delivery and the need to perform a caesarean section at term seem to be more common.

Pulse wave Doppler ultrasound of umbilical cord in experimentally induced pregnancy toxemia in sheep

Contrary to its widespread use in human cases, the use of Doppler ultrasonography is only recently becoming prevalent in farm animals. This study aimed to determine the effects of maternal metabolic and clinical changes on fetal hemodynamics during pregnancy toxemia with the doppler examination of umbilical cord. In the study twenty ewes with a single healthy fetus were included in the study. At the end of the 120th day of pregnancy, 20 single-bearing pregnant ewes were randomly categorized into two groups. Ewes in the control group were fed to meet all nutritional requirements. On the other contrary, the experimental ewes were fed to meet equivalent to 50 % of the daily needs and then fasted for 96 h. Doppler ultrasonographic examinations of umbilical cord were performed once every two days and once a day during fasting. Beta hydroxybutyric acid (BHBA) concentration was measured by taking blood from sheep on examination days. Pulse systolic velocity (PSV), end diastolic velocity (EDV), PSV/EDV, pulsatility index (PI), resistance index (RI), and fetal heart rate (FHR) as well as BHBA values and how those parameters has changed over time (time by treatment effect) due to energy deprivation during pregnancy were evaluated using repeated measure analysis of variance. No clinical signs were observed in both toxemia and control groups during restricted feeding. BHBA concentration increased and there was a significant time, time by treatment and main effect of treatment effect between groups. No significant main effect of treatment and time by treatment interaction was observed in the changes of PI, RI, FHR, and systolic/diastolic velocity values over time in both groups. FHR was reduced over time, and there was a significant time effect in FHR in both groups. Although doppler indices didn't increase, both PSV and EDV values increased significantly in the pregnancy toxemia group compared with the controls (Time P = 0.03, time by treatment interaction P < 0.05) and the main effect of treatment P < 0.05). The marked increase in blood velocities (PSV and EDV) in the umbilical cord is probably due to the compensatory functioning for excessive energy deprivation of the fetus. Therefore, PSV and EDV might be a valuable indicator for evaluating the fetus's health status during the management of the PT.

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

BACKGROUND

Ultrasonography is one of the most important techniques that enable the detection and monitoring of pregnancy. One such study using this technique is the assessment of the hemodynamics of fetal and umbilical blood vessels. However, there is little data on blood flow in the placentomes, which is the basic structural unit of the sheep's placenta. Therefore, the aim of this study was to determine the Doppler parameters in the arterial vessels of the caruncles, cotyledons and the umbilical cord as well as measuring venous flow rates during the entire gestation period of the sheep. Additionally, the usefulness of various other ultrasound parameters in the early diagnosis of pregnancy in sheep was analyzed.

RESULTS

Most of the Doppler parameters in umbilical, cotyledonary and caruncular arteries were significantly correlated with the day of pregnancy (p < 0.01). In the early stages of pregnancy, the peak systolic velocity (PSV), regardless of the location of the artery, was significantly lower than that in the later stages of pregnancy (p < 0.01). PSV was also found to be significantly higher in the umbilical artery than in the cotyledonary and caruncular arteries (p < 0.01). Until the 50th day of pregnancy, the end diastolic velocity (EDV) was not found in the umbilical and cotyledonary arteries. EDV was significantly higher in the caruncular arteries than in the cotyledonary and umbilical arteries (p < 0.01). The resistance index (RI) and pulsatility index (PI) in the early stages of pregnancy were found to be significantly higher than that in the later stages of pregnancy (p < 0.01). The RI and PI were significantly lower in the caruncular arteries than in the arteries of the cotyledons and umbilical cord (p < 0.01). In the umbilical vein, all Doppler parameters were observed to be significantly higher than those in the placentomal veins (p < 0.01 or p < 0.05). Using transrectal ultrasound, pregnancy was detected between 20 and 28 days after mating. The ovaries were observed to have corpora lutea, the diameter of which was fairly consistent from the 17th to the 56th day of pregnancy.

CONCLUSIONS

It has been demonstrated that both the location of the arterial vessel in the placental-umbilical circulation and the gestational age have a significant impact on hemodynamic parameters. The results also provide new insights about the blood flow in caruncular and cotyledonary arteries, which could contribute to a more holistic understanding of hemodynamic changes in the placentas of sheep. Analyzing haemodynamic parameters in the umbilical and placental veins are preliminary studies in sheep, but it could inspire further research in this field. Furthermore, the research conducted confirms the practicality and convenience of transrectal ultrasonography in the early diagnosis of pregnancy in sheep and also indicates that the identification and imaging of the corpus luteum using B-mode ultrasonography can be a very early and simple method of confirming effective mating in sheep.

Doppler ultrasound measurements of the blood flow velocity in the fetal heart and aorta in Bulgarian White milk goats

The aim of the present study was to determine the parameters characterising the blood flow velocity in the fetal heart and aorta in goats by Doppler ultrasonography. Twenty-four Bulgarian White milk goats, aged 4-6 years, weighing 45-51 kg were used in the study. Doppler ultrasound measurements of the blood flow velocity in fetal heart were done at the end of first, second and third trimesters of pregnancy, and in the fetal aorta - at the end of the second and third trimesters of pregnancy. Ultrasound investigations were carried out by transabdominal approach with linear and convex transducers, with frequency 8.0 MHz. Blood flow parameters that included maximum and minimum systolic velocity, end-diastolic velocity, pulsatility index, resistance index and systolic/diastolic ratio were measured by spectral Doppler ultrasonography. The results showed that the highest maximum systolic velocity in the fetal heart was observed at the end of the first pregnancy trimester. Statistically significantly (p < 0.05) lower values of this parameter were registered in the second and third pregnancy trimesters. A similar tendency was observed for minimum systolic velocity, end-diastolic velocity and systolic/diastolic ratio. The pulsatility index and resistance index had similar values for the three studied periods. Examination of the fetal aorta showed statistically significant differences (p < 0.05) of minimum systolic velocity, end-diastolic velocity, pulsatility and resistance index in the third, compared with the second trimester of pregnancy. The analysis of the results suggested that Doppler ultrasonography can be used to monitor fetal blood flow changes during the various stages of pregnancy.