Reliability of measurements of facial profile parameters by operators with different levels of experience at 15 to 23 weeks of gestation.

Abstract

To compare the reliability of measurements of five fetal facial profile parameters by operators with different levels of experience, at 15 to 23 weeks of gestation in Thai fetuses. An observational study was conducted. The inferior facial angle, anteroposterior mandibular diameter, mandible width, maxilla width, and mandible length were measured in 123 normal fetuses, using 2D ultrasonography, by three operators with different levels of experience. Each participant was examined by two 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. Bland-Altman analysis was used to evaluate agreement. The ability to obtain a mandible length measurement was highest (100%) among the five parameters. Intraobserver variabilities of anteroposterior mandibular diameter, mandible width, maxilla width, and mandible length measurements were excellent for all operators (ICC 0.958-0.986), while those of inferior facial angle measurements were moderate to excellent (ICC 0.560-0.923), depending on the operators' experience. Interobserver variabilities varied between pairs of operators; only two parameters, anteroposterior mandibular diameter and mandible length, showed excellent interobserver variabilities (ICC >0.9), with good agreement. The mandible length measurement was the best parameter in terms of feasibility and reliability.