Learning Curve for Ultrasound Assessment of Myometrial Infiltration in Endometrial Cancer Visualizing Videoclips: Potential Implications for Training

Background: Diagnostic accuracy for estimating myometrial infiltration by ultrasound in endometrial cancer requires experience. The objective of this study is to determine the learning curve (LC) for assessing myometrial infiltration in cases of endometrial cancer using transvaginal ultrasound (TVS). Methods: Five trainees (one staff radiologist and four fourth-year OB/GYN residents) participated in this study. All trainees had experience in performing TVS, but none of them had specific training on the assessment of myometrial infiltration. Trainees were given one specific lecture about the topic, and then they observed videoclips from 10 cases explained by the trainer. After this, all trainees visualized 45 videoclips of uterine ultrasound scans of endometrial cancer cases. The assessment of myometrial infiltration was based on the subjective impression. Definitive histology was used as a reference standard. Trainees stated whether myometrial infiltration was ≥50% or <50%. LC-CUSUM and standard CUSUM graphics were plotted to determine how many cases were needed to reach competence, allowing a mistake rate of 15%. Results: All trainees completed the study. LC-CUSUM graphics showed that three trainees reached competence at the 33rd, 35th and 36th case, respectively. All three of them kept the process under control after reaching competence. One trainee reached competence but did not maintain it in the cumulative analysis. One trainee did not reach competence. Conclusion: Our study suggests that 30-40 cases would be needed to be trained for assessing myometrial infiltration by TVS by visual interpretation of videoclips by most trainees.