Background/Objectives: First-trimester anatomical screening (FTAS) enables early detection of fetal structural anomalies. However, data on transvaginal ultrasound performance across different operator experience levels remains limited. The primary objective was to compare the performance of transvaginal FTAS between inexperienced and experienced operators by comparing complete scan rates and anatomical visualization scores. The secondary objectives were to compare scan duration and learning curves between the two operators and to identify factors associated with successful examinations. Methods: In this randomized controlled trial, participants underwent transvaginal FTAS performed either by a first-year maternal–fetal medicine (MFM) fellow (inexperienced operator) or an MFM specialist (experienced operator) according to International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) guidelines. Complete scan rates, anatomical visualization scores, scan duration, factors affecting visualization, and learning curves were compared between groups. Results: A total of 139 participants were included in the analysis, with 70 and 69 examinations performed by the inexperienced and experienced operators, respectively. Complete scan rates and visualization scores were not significantly different between groups (41.4% vs. 44.9% and 86.4% vs. 91.2%, respectively). On multivariate analysis, operator experience was independently associated with higher visualization scores (p = 0.010), but not complete scan rates. Scan duration was similar between groups (median (IQR): 20 (17) vs. 20 (15) min; p = 0.211). Fetal presentation and uterine position significantly influenced visualization outcomes. The inexperienced operator demonstrated a trend of gradual improvement over time, though not significantly, whereas the experienced operator maintained stable performance throughout the study period. Conclusions: After training, no statistically significant differences were observed between less experienced and experienced operators with respect to complete scan rate, scan duration, and learning curve, although visualization score was significantly higher in the experienced examiner on multivariate analysis. However, our findings should be interpreted with caution, as the conclusions were based on the performance of only one examiner in each group.

Objectives: To primarily determine the effect of a previous cesarean section on Doppler studies of the uterine artery, umbilical artery, and umbilical vein. Patients and Methods: This prospective study was conducted on singleton pregnancies between 18 and 22 weeks of gestation, including both women with and without a previous cesarean section. Doppler studies of the uterine artery, umbilical artery, and umbilical vein indices were performed during mid-trimester fetal ultrasound scans. Doppler indices and pregnancy outcomes were compared between the two groups. Results: A total of 351 pregnancies, including 74 women with a previous cesarean section and 277 women with an unscarred uterus, underwent Doppler studies. The uterine artery pulsatility index (PI) and resistance index (RI) were significantly higher in women with a previous cesarean section (p < 0.001). Moreover, both univariate and multivariate analyses demonstrated that a previous cesarean section was significantly associated with an increase in uterine artery PI, RI, and the rate of abnormal uterine artery PI, defined as values above the 95th percentile (p = 0.034). Other Doppler study results, as well as pregnancy outcomes, were comparable between the two groups. Conclusions: Pregnant women with a previous cesarean section have significantly higher uterine artery resistance, and a higher rate of abnormal uterine artery PI during mid-pregnancy. Therefore, a cesarean section may be detrimental to uterine arterial health. However, no significant adverse clinical outcomes were observed.