Ultrasound assessment of biometric parameters of the head and brain and Doppler indices in cerebral arteries in sheep in the prenatal period

The aim of this study was to perform a biometric analysis of the head in sheep embryos/fetuses and to determine Doppler parameters in the middle cerebral artery and umbilical artery in 12 prenatal sheep. Using B-Mode ultrasound, the biparietal distance (BPD), occipital-nasal length (ONL), eye length and width, choroid plexus width, and turbinate complex width were determined. Peak systolic velocity (PSV), end diastolic velocity (EDV), PSV/EDV ratio, resistance index (RI) and pulsatility index (PI) were also determined. From the 26th to the 110th day of pregnancy, a progressive increase in BPD and ONL was observed (p<0.01 and p<0.05). The width of the choroid plexus increased until the 96th day of pregnancy (p<0.01 and p<0.05). The PSV in the MCA during the last period of pregnancy was higher than in the first period of pregnancy (p<0.05). A similar trend was noted for EDV (p<0.01). PSV/EDV, RI and PI at the end of pregnancy were the lowest. In the first period of pregnancy, EDV was higher in the MCA than in the UA (p<0.01), but in subsequent periods these differences were reversed (p<0.05, p<0.01). In the first stage of pregnancy, RI and PI in the MCA were lower than in the UA (p<0.01) but in subsequent periods of pregnancy these differences were reversed. The results indicate that several parameters that indicate changes in the heads of prenatal sheep can be detected ultrasonographically.