VP24.06: Visualisation of brain vesicles as part of a routine eight‐week ultrasound scan

Abstract

To describe the sonographic appearance and size of the fetal aqueduct of Sylvius (AoS) in the first trimester of pregnancy. Methods: Single centre prospective study including a non-consecutive series of normal fetuses at 11-13 weeks gestational age (CRL between 45 and 84mm). A volume dataset was acquired by transvaginal ultrasound starting from the axial view of the fetal head. All acquired volumes were processed to evaluate the appearance and diameters of the AoS on the three orthogonal planes. Length, height and width of the AoS were measured by two different operators, and inter-observer repeatability was assessed (interclass correlation, IC). For each parameter, the mean of the two operators' measurements was used for further analysis. Results: Overall, 29 fetuses were included in the study. At off-line analysis of the acquired volumes the AoS was visible in all cases, with a mean length and height of 4,74 ± 0.36 mm and 1.97 ± 0.33 mm on the midsagittal plane. The AoS width was 1.92 ± 0.29 mm on the axial plane. For AoS length and width measurements an excellent interobserver repeatability was found, with IC coefficient (ICC) 0.911 and 0.920, respectively, whereas repeatability was good for width (ICC = 0.809). Conclusions: AoS may be measured at first trimester 3D ultrasound with good or excellent interobserver repeatability.