767 Transvaginal ultrasound for assessing myometrial infiltration in endometriod endometrial cancer: learning curve

Introduction/Background* Determining the degree of myometrial infiltration allows establishing the best therapeutic approach for each patient as it is an important factor in predicting nodal metastases. Few prospective studies comparing the diagnostic performance of transvaginal ultrasound (TVS) and magnetic resonance imaging (MRI) in the preoperative local staging of endometrial carcinoma have been reported. In fact, a recent meta-analysis has shown that both techniques have similar diagnostic accuracy. However, to the best of our knowledge, there has been no prospective comparison of the diagnostic performance of TVS and MRI in the same group of patients with low-grade endometrial cancer. The aim of this study was to analyse the learning curve when assessing myometrial infiltration by transvaginal ultrasound. Methodology Observational prospective study performed at a single tertiary care centre from 2016 to 2020, comprising 156 consecutive patients diagnosed by endometrial sampling as having an endometrioid grade 1/grade2 endometrial cancer. TVS and MRI were performed prior to surgical staging for assessing MI, which was estimated using subjective examiner’s impression and Karlsson’s method for both TVS and MRI. During surgery, intraoperative assessment of MI was also performed. Definitive pathological study considered as reference standard. CUSUM graphs have been used to determine the number of necessary cases to reach the competence, admitting an error rate of between 10% and 25% as the expected precision of an expert is approximately 85%. Result(s)* The main sonographer of this study achieved proficiency after having sonographically evaluated 39 patients. Conclusion* There is a learning process for the ultrasound assessment of the degree of myometrial infiltration that influences the diagnostic performance of transvaginal ultrasound. The learning curve of the lead sonographer in this study showed that she reached proficiency after sonographic study of 39 patients.