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

Abstract

Aim To establish reference ranges for fetal mandibular markers in low‐risk singleton pregnancies between 11 and 13 + 6 weeks of gestation in a Chinese population. Methods The inferior facial angle (IFA), transverse, and anteroposterior diameters of the mandible, and mandibular length were measured at 11–13 + 6 weeks of gestation. The utility of these sonographic markers for detecting micrognathia was explored in seven fetuses. Results In healthy fetuses at 11–13 + 6 weeks, there were linear correlations between gestational age and the transverse (Y = −15.615 + 1.987X, r = 0.718, p < 0.001) and anteroposterior (Y = −8.557 + 1.101X, r = 0.581, p < 0.001) diameters of the mandible; mean ratio of the anteroposterior: transverse diameters of the mandible decreased with gestational age (Y = 0.603–0.003X, r = 0.018, p = 0.755); there was a positive correlation between crown rump length and mandibular length (mandible length = 0.861 + 0.137*crown rump length; r = 0.723, p < 0.001); and there was a positive correlation between crown rump length and IFA (r = 0.234, p < 0.05). Reference ranges were: mean ratio of anteroposterior diameter: transverse diameter of the mandible 0.56; mean mandibular length 9.05 mm; and median IFA 66.5°. The values for these mandibular markers in seven cases of fetal micrognathia were outside the normal range. Conclusions Evaluations of fetal mandibular markers during first trimester ultrasound screening may contribute to the early detection and diagnosis of micrognathia. We recommend obtaining a subjective impression of the mandible on the mid‐sagittal view routinely used to measured nuchal translucency, followed by targeted objective measurements on the mid‐sagittal and axial views in suspected cases.

Prenatal diagnosis of micrognathia: a systematic review

“…Nineteen articles described cross-sectional studies (76 percent) ( 15 – 17 , 19 – 26 , 28 – 33 , 36 , 40 ), 4 (16 percent) were case-control studies ( 34 , 35 , 37 , 39 ), and 2 (8 percent) were cohort studies ( 27 , 38 ). Fifteen studies (60 percent) had a prospective design ( 15 – 17 , 20 – 28 , 30 , 31 , 36 , 40 ), 9 (36 percent) had a retrospective design ( 20 , 33 – 35 , 37 – 39 ), and one (4 percent) had both prospective and retrospective design ( 32 ). Thirty-two percent of the studies ( n = 8) were performed in USA ( 21 – 23 , 29 , 34 , 35 , 37 , 39 ), and the remaining studies were performed in China ( n = 4) ( 20 , 25 , 36 , 40 ), Israel ( n = 3) ( 26 , 28 , 38 ), Netherlands ( n = 3) ( 27 , 30 , 31 ), UK ( n = 1) ( 15 ), France ( n = 1) ( 24 ), Italy ( n = 1) ( 16 ), Belgium( n = 1) ( 17 ), Germany ( n = 1) ( 19 ), Spain ( n = 1) ( 32 ), and Austria ( n = 1) ( 33 ).…”

“…Fifteen studies (60 percent) had a prospective design ( 15 – 17 , 20 – 28 , 30 , 31 , 36 , 40 ), 9 (36 percent) had a retrospective design ( 20 , 33 – 35 , 37 – 39 ), and one (4 percent) had both prospective and retrospective design ( 32 ). Thirty-two percent of the studies ( n = 8) were performed in USA ( 21 – 23 , 29 , 34 , 35 , 37 , 39 ), and the remaining studies were performed in China ( n = 4) ( 20 , 25 , 36 , 40 ), Israel ( n = 3) ( 26 , 28 , 38 ), Netherlands ( n = 3) ( 27 , 30 , 31 ), UK ( n = 1) ( 15 ), France ( n = 1) ( 24 ), Italy ( n = 1) ( 16 ), Belgium( n = 1) ( 17 ), Germany ( n = 1) ( 19 ), Spain ( n = 1) ( 32 ), and Austria ( n = 1) ( 33 ). From 25 studies included in the qualitative synthesis, 14 studies (56 percent) used two-dimensional (2D) ultrasound for prenatal examination of fetuses ( 15 – 17 , 19 – 23 , 26 , 28 , 31 , 36 , 39 , 40 ), 4 (16 percent) used magnetic resonance imaging (MRI) ( 33 – 35 , 38 ), 5 (20 percent) used three-dimensional (3D) ultrasound, 1 (4 percent) used both 2D ultrasound and MRI ( 37 ), 1 (4 percent) used both 2D and 3D ultrasound ( 32 ).…”

“…Six of these studies performed the regression analysis between IFA and GA or between IFA and crown rump length (CRL). The study carried out by Li et al showed a weak positive correlation between IFA and CRL from 11 to 13 +6 weeks, and the median IFA was 66.5° with 25th and 75th percentiles of 62.5° and 70.4° ( 20 ). The study carried out by Lu et al showed that the IFA increased slightly with gestation from 16 weeks till approximately 28–31 weeks, at 1° to 2° per week, and decreased minimally thereafter ( 36 ).…”

“…The mandible length was measured as the distance between the cartilaginous symphysis menti and the temporomandibular joint ( Figure 2G ). Of the 25 included studies, 3 measured the mandible length of fetuses ( 15 , 20 , 21 ). In these studies, the mandible length was plotted against GA and CRL as independent variables to build the growth charts, and was positively correlated with GA and CRL in all three trimesters.…”

“…The jaw index was then calculated as follows: APD/biparietal diameter × 100. Of the 25 included studies, 5 measured the APD ( 16 , 20 , 22 , 33 , 38 ) and 3 measured the TD of fetuses ( 16 , 20 , 22 ). All studies showed both APD and TD were positively correlated with GA. Zalel et al reported that, in healthy fetuses at 11–31 weeks, there was a positive correlation between APD/TD and GA ( 28 ).…”