OC10.04: Ultrasound evaluation of the development of olfactory sulcus in normal fetuses: a cross‐sectional study

To create a standardised reference chart for fetal olfactory sulcus length using 2D ultrasound scans from 23 to 39 weeks of gestation. Additionally, it sought to prospectively monitor abnormal cases. A prospective cross-sectional study was conducted between 2021 and 2023 in well-dated, low-risk, singleton pregnancies between 23 and 40 weeks of gestation. A transfrontal coronal plane was utilised to obtain a standardised image of the olfactory sulci. measurements conducted by four trained sonographers. Intra- and interobserver variability were evaluated, and olfactory sulcus length percentiles (1st to 99th) were calculated for each gestational week. Three hundred and sixty-one fetuses from low-risk pregnancies met stringent inclusion criteria, demonstrating measurable olfactory sulci in 78% of cases at 23 weeks gestation, and in all cases from 24 weeks onwards A high intra- and interobserver variability was found for both intra, 0.992 (95% Confidence Interval 0.988-0.995) and intraobserver variability, 0.991 (95% Confidence Interval 0.981-0.996) indicating an excellent correlation between the two groups of measurement. Significant positive correlations were observed between olfactory sulcus length, fetal biometric parameters, and gestational age (p < 0.001). Nomograms indicated a normal distribution per week. Fetal brain ultrasound can detect developing olfactory sulci as early as 23 weeks' gestation. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.