Ultrasonographic Study of Fetal Facial Profile Markers During First Trimester

Abstract

Background: To establish normal reference ranges of fetal facial profile markers, and to study their correlation with crown-rump length (CRL) during first trimester (11~13+6 weeks’ gestation) in a Han Chinese population. Methods: Ultrasonographic images of measuring fetal nuchal translucency (NT) were retrospectively selected randomly in normal pregnancies where both parents were of Han Chinese ethnicity. The facial markers included inferior facial angle (IFA), maxilla-nasion-mandible (MNM) angle, facial maxillary angle (FMA) and profile line (PL) distance. These markers were measured through ViewPoint 6 software by two experienced sonographers.Results: Three hundred and eighty fetuses were selected. The ICCs (95% CI) of intra-operator 1 reproducibility of IFA, MNM angle, FMA, PL distance were 0.944 (0.886~0.973), 0.804 (0.629~0.902), 0.834 (0.68~0.918) and 0.935 (0.868~0.969), respectively. The ICCs (95% CI) of intra-operator 2 reproducibility of IFA, MNM angle, FMA, PL distance were 0.931 (0.857~0.967), 0.809 (0.637~0.904), 0.786 (0.600~0.892) and 0.906 (0.813~0.954), respectively. The ICCs (95% CI) of inter-operator reproducibility of IFA, MNM angle, FMA, PL distance were 0.885 (0.663~0.953), 0.829 (0.672~0.915), 0.77 (0.511~0.891) and 0.844 (0.68~0.925), respectively. The average±SD of IFA, MNM angle, FMA and PL distance were 80.2°±7.25°, 4.17°±1.19°, 75.36°±5.31°, 2.78±0.54 mm, respectively. IFA and PL distance significantly decreased with CRL, while MNM angle and FMA significantly increased with CRL.Conclusion: It was feasible to measure fetal facial markers during first trimester. The normal range of each marker was obtained through large sample data, and the measurements were found to correlate with CRL.

Clinical value of fetal facial profile markers during the first trimester

“…(1) IFA [4,5,11]: the angle between the line orthogonal to the vertical part of the forehead at the level of the synostosis of the nasal bones and a second line joining the tip of the mentum to the anterior point of the more protruding lip (Fig. 1).…”

“…(2) MNM angle [6,11]: the angle between the maxilla-nasion line and the mandible-nasion line (Fig. 2).…”

“…2). The nasion [10,11] was defined as the most anterior point at the intersection of the frontal and nasal bone.…”

Ultrasonographic study of fetal mandibular markers during the first trimester in a Chinese population

“…5,[11][12][13] A previous ultrasonographic study established reference ranges for fetal facial profile markers during the first trimester in a Chinese population. 14 To the authors' knowledge, no ultrasonographic study has developed a dedicated protocol that provides objective criteria for the early detection of abnormalities of the mandible at 11-13 weeks of gestation.…”

“…Most studies report on the diagnosis of micrognathia on prenatal sonography during the second and third trimester 7–10 ; however, with adequate ultrasound operator awareness, experience and skill, micrognathia is potentially detectable in the first trimester 5,11–13 . A previous ultrasonographic study established reference ranges for fetal facial profile markers during the first trimester in a Chinese population 14 . To the authors' knowledge, no ultrasonographic study has developed a dedicated protocol that provides objective criteria for the early detection of abnormalities of the mandible at 11–13 weeks of gestation.…”