Rotten D, Levaillant J M, Martinez H, Ducou le Pointe H, Vicaut E
Department of Gynecology and Obstetrics, Delafontaine Hospital, Saint-Denis, Paris, France.
Ultrasound Obstet Gynecol. 2002 Feb;19(2):122-30. doi: 10.1046/j.0960-7692.2001.00622.x.
To define parameters that enable the objective diagnosis of anomalies of the position and/or size of the fetal mandible in utero.
Fetuses at 18-28 gestational weeks were examined by two- and three-dimensional ultrasound. The study included normal fetuses and fetuses with syndromes associated with known mandible pathology: Pierre Robin sequence or complex (n = 8); hemifacial microsomia (Treacher-Collins syndrome, n = 3); postaxial acrofacial dysostosis (n = 1). Fetuses with Down syndrome (n = 8) and cleft lip and palate without Pierre Robin sequence or complex (n = 18) were also studied. Retrognathia was assessed through the measurement of the inferior facial angle, defined on a mid-sagittal view, by the crossing of: 1) the line orthogonal to the vertical part of the forehead at the level of the synostosis of the nasal bones (reference line); 2) the line joining the tip of the mentum and the anterior border of the more protruding lip (profile line). Micrognathia was assessed through the calculation of the mandible width/maxilla width ratio on axial views obtained at the alveolar level. Mandible and maxilla widths were measured 10 mm posteriorly to the anterior osteous border.
In normal fetuses, the inferior facial angle was constant over the time span studied. The mean (standard deviation) value of the inferior facial angle was 65.5 (8.13) degree. Consequently, an inferior facial angle value below 49.2 degree (mean - 2 standard deviations) defined retrognathism. All the fetuses with syndromes associated with mandible pathology had inferior facial angle values below the cut-off value. Using 49.2 degree or the rounded-up value of 50 degree as a cut-off point, the inferior facial angle had a sensitivity of 1.0, a specificity of 0.989, a positive predictive value of 0.750 and a negative predictive value of 1.0 to predict retrognathia. In normal fetuses, the mandible width/maxilla width ratio was constant over the time interval studied. The mean (standard deviation) value was 1.017 (0.116). Consequently, a mandible width/maxilla width ratio < 0.785 defined micrognathism. Mandible width/maxilla width ratio values were below this cut-off point in eight and in the normal range in four fetuses with syndromes associated with mandible pathology.
Retrognathia and micrognathia are conditions that can be separately assessed. The use of inferior facial angle and mandible width/maxilla width ratio should help sonographic recognition and characterization of fetal retrognathic and micrognathic mandibles in utero.
确定能够对子宫内胎儿下颌骨位置和/或大小异常进行客观诊断的参数。
对妊娠18 - 28周的胎儿进行二维和三维超声检查。该研究包括正常胎儿以及患有与已知下颌骨病变相关综合征的胎儿：皮埃尔·罗宾序列或综合征（n = 8）；半侧颜面短小畸形（特里彻 - 柯林斯综合征，n = 3）；轴后性肢端颜面发育不全（n = 1）。还对患有唐氏综合征（n = 8）以及唇腭裂但无皮埃尔·罗宾序列或综合征的胎儿（n = 18）进行了研究。通过测量在下矢状面上定义的面下角度来评估下颌后缩，该角度由以下两条线相交而成：1）在鼻骨联合水平与前额垂直部分正交的线（参考线）；2）连接颏尖与更突出唇部前缘的线（轮廓线）。通过计算在牙槽水平获得的轴位视图上的下颌骨宽度/上颌骨宽度比值来评估小下颌。下颌骨和上颌骨宽度在骨前缘后方10 mm处测量。
在正常胎儿中,在所研究的时间段内面下角度恒定。面下角度的平均（标准差）值为65.5（8.13）度。因此，面下角度值低于49.2度（平均值 - 2个标准差）定义为下颌后缩。所有患有与下颌骨病变相关综合征的胎儿面下角度值均低于临界值。使用49.2度或向上取整值50度作为临界点，面下角度预测下颌后缩的敏感性为1.0，特异性为0.989，阳性预测值为0.750，阴性预测值为1.0。在正常胎儿中，在所研究的时间间隔内下颌骨宽度/上颌骨宽度比值恒定。平均（标准差）值为1.017（0.116）。因此，下颌骨宽度/上颌骨宽度比值<0.785定义为小下颌。在患有与下颌骨病变相关综合征的胎儿中，8例胎儿的下颌骨宽度/上颌骨宽度比值低于该临界点，4例在正常范围内。
下颌后缩和小下颌是可以分别评估的情况。使用面下角度和下颌骨宽度/上颌骨宽度比值应有助于超声识别和描述子宫内胎儿下颌后缩和小下颌的特征。
