Learning Curve for Ultrasound Assessment of the Fetal Heart at Nuchal Scan

Background: The aim of our study was to evaluate the characteristics of the learning curve of the first trimester (FT) fetal heart scan and to determine the required number of ultrasound examinations for training sonographers to accurately assess the normal fetal heart at 11–13+6 weeks’ gestation, by means of 2D ultrasound. Methods: We selected four trainees (resident doctors) with theoretical knowledge and limited experience in FT/ST scan but without prior experience in performing first trimester fetal heart assessment. Each of them performed fetal heart ultrasound scanning in a cohort of 100 consecutive fetuses with normal heart during the routine nuchal translucency (NT scan), upon a pre-established protocol. The supervising doctor recorded if the sonographer succeeded in obtaining an informative 2D/2DC duplex sweep of the fetal heart. The time limit for scanning was 10 minutes. The data were analysed in three groups of examinations. Individual learning curves were delineated using moving average method. Results: For all the trainees, there was a positive relationship between the number of FT scans and the number of good quality acquired clips. Assessment of fetal structures in first trimester can be accurately achieved by an inexperienced trainee after scanning 50 cases on average. The operating time was stabilized after 80 cases in moving average analysis. Conclusion: Repeated scans increase ability to acquire good quality fetal heart sweep digital clips at the end of the first trimester of pregnancy. FT fetal heart ultrasound assessment is a relatively simple procedure to learn and, once a moderate degree of experience is gained, should be routinely incorporated into NT scan. Policymakers should decide safety studies in respect to FT Doppler use in order to generalize the technique. After an adequate training the heart assessment does not prolong the nuchal scan.