Probe motion during mid-trimester fetal anomaly scan in the clinical setting: A prospective observational study

•Why was this study conduted?•Some study investigated probe motion in simulated settings, but few in a clinical setting during second trimester scans. We hypothesized that probe trajectory might differ according to operator’s level, fetal presentation (e.g., cephalic or breech) or patient body mass index (BMI).•What does this study add?•In a clinical setting, some differences in the path metrics (velocity, acceleration, jerk and working volume) were noticed according to participant level. However, angular metrics, i.e., the quantity of rotation applied to the probe, were not affected by operator’s level, fetal presentations nor patient’s BMI. This study aims to investigate probe motion during full mid-trimester anomaly scans. We undertook a prospective, observational study of obstetric sonographers at a UK University Teaching Hospital. We collected prospectively full-length video recordings of routine second-trimester anomaly scans synchronized with probe trajectory tracking data during the scan. Videos were reviewed and trajectories analyzed using duration, path metrics (path length, velocity, acceleration, jerk, and volume) and angular metrics (spectral arc, angular area, angular velocity, angular acceleration, and angular jerk). These trajectories were then compared according to the participant level of expertise, fetal presentation, and patient BMI. A total of 17 anomaly scans were recorded. The average velocity of the probe was 12.9 ± 3.4 mm/s for the consultants versus 24.6 ± 5.7 mm/s for the fellows (p = 0.02), the average acceleration 170.4 ± 26.3 mm/s2 versus 328.9 ± 62.7 mm/s2 (p = 0.02), and the average jerk 7491.7 ± 1056.1 mm/s3 versus 14944.1 ± 3146.3 mm/s3 (p = 0.02), the working volume 9.106 ± 4.106 mm3 versus 29.106 ± 11.106 mm3 (p = 0.03), respectively. The angular metrics were not significantly different according to the participant level of expertise, the fetal presentation, or to patients BMI. Some differences in the probe path metrics (velocity, acceleration, jerk and working volume) were noticed according to operator’s level.