Objective: To evaluate the intra- and interobserver reproducibility of three-dimensional power Doppler sonography (3D power Doppler) in the assessment of fetal brain blood flow in the middle cerebral artery territory. Materials and methods: A cross-sectional study was developed with 20 healthy pregnant women between 26 and 34 gestational weeks. The middle cerebral artery territory closest to the transducer was scanned and the blood flow volume was calculated with the method Virtual Organ Computer-aided AnaLysis. The following 3D power Doppler indices were later obtained: vascularization index (VI), flow index (FI) and vascularization-flow index (VFI). The intraclass correlation coefficient (ICC) and Bland-Altman plots were utilized for calculating the intra- and interobserver variability. Results: A good intra- and interobserver agreement was observed, with ICC > 0.90 for all the 3D power Doppler indices: VI [ICC = 0.992 (CI 95%: 0.981–0.997)], FI [ICC = 0.999 (CI 95%: 0.998–0.999)], VFI [ICC = 0.995 (CI 95%: 0.987–0.998)]. Interobserver reproducibility: VI [ICC = 0.988 (CI 95%: 0.970–0.995)], FI [ICC = 0.999 (CI 95%: 0.997– 1.000)], VFI [ICC = 0.994 (CI 95%: 0.994–0.998)]. Conclusion: 3D power Doppler has shown to be a practical and easy method in the assessment of fetal brain blood flow, with good intra- and interobserver reproducibility. The FI presented the best intra- and interobserver agreement.

Keywords: Reproducibility of results; Prenatal ultrasonography; Fetal brain flow; Power Doppler; Threedimensional sonography.

Central nervous system malformations constitute the second most common group of anomalies in fetuses. Such malformations have assumed clinical importance because of their association with high rates of perinatal morbidity and mortality. Therefore, it is extremely important to assess the fetal central nervous system during the prenatal period, in order to identify any changes in its development and thereby gain sufficient information to advise parents about pregnancy follow-up, options for fetal therapy, and the timing/type of delivery, as well as the postnatal treatment and prognosis. The objective of this review was to describe the ultrasonographic evaluation of the fetal central nervous system as per the guidelines of the International Society of Ultrasound in Obstetrics and Gynecology.

Keywords: Fetus; Central nervous system; Ultrasonography; Practice guidelines as topic.

Ultrasound diagnosis of posterior fossa malformations in the prenatal period is a challenge, having major implications for the counseling and follow-up of pregnant women. The purpose of this study was to review aspects of the ultrasound evaluation of the fetal posterior fossa, as well as to describe the most relevant ultrasound findings of the main posterior fossa malformations that can affect the fetus in the prenatal period.

Keywords: Prenatal diagnosis/methods; Ultrasonography/methods; Cranial fossa, posterior/abnormalities; Cerebellum/embryology.