Comparison of reliability of measurements among fetal facial profile parameters by operators with different levels of experience at 15-23 weeks of gestation

Abstract Background Mandible anomalies are associated with many syndromes. Various methods have been proposed to assess fetal mandibles with different reliability. This study aimed to compare the reliability of measurements among five fetal facial profile parameters by operators with different levels of experience, at 15–23 weeks of gestation in Thai fetuses. Methods An observational study was prospectively conducted. The inferior facial angle (IFA), anteroposterior mandibular diameter (APD), mandible width (MD), maxilla width (MX) and mandible length (ML) were measured in 123 normal fetuses, using 2D ultrasonography, by 3 operators with different levels of experience. Each participant was examined by 2 operators. Each operator performed three independent measurements for each parameter and was blinded to the results of the other. Reliability of measurement was evaluated using intraclass correlation coefficient for both intraobserver and interobserver variabilities. Bland-Altman analysis was used to evaluate the agreement between operators’ measurements. Results The success rate of ML measurement was highest (100%) among the five parameters for all operators. Failure of MX measurement was high in fetuses at a gestational age of less than 18 weeks. Intraobserver variabilities of APD, MD, MX and ML measurements were excellent for all operators (ICC 0.958–0.986), while those of IFA measurement was moderate to excellent (0.560–0.923), depending on the operators’ experience. Interobserver variabilities varied between pairs of operators; only 2 parameters, APD and ML, showed excellent interobserver variabilities for both pairs of operators (ICC > 0.9) with good agreement. Interobserver variabilities of MX measurements for both pairs of operators were good (ICC 0.606–0.709), while MD was excellent for operator 1 and 2 (ICC 0.867), but moderate for operator 1 and 3 (ICC 0.576) and IFA was good for operator 1 and 2 (ICC 0.602), but poor for operator 1 and 3 (ICC 0.128). Conclusions The reliability of ML measurement was the highest, followed by APD, while IFA was the lowest, among the 5 parameters. ML and APD measurements were feasible and reproducible, whereas MX measurement was limited in fetuses with a gestational age of less than 18 weeks. Additionally, reliability of IFA measurement depended on the operator’s experience.