Supplementary Material for: Fetal Ultrasonic Evaluation of Bronchial Morphology in Fetuses with Isomerism

Objective: The aim of the study was to evaluate whether fetal ultrasound could determine bronchial isomerism and distinguish left isomerism from right isomerism. Methods: We identified 110 healthy fetuses and 28 fetuses with isomerism. The outer angle between the tracheal midline and the inner margin of the bronchus is measured. The bronchial angles and the ratio of left/right bronchial angle were used to differentiate bronchial morphology and confirm the presence of bronchial isomerism in pathological cases. Results: The normal angles of the left and right bronchi were 146.98° (95% CI, 145.15–147.81°) and 167.37° (95% CI, 166.30–168.44°), separately. The cutoff bronchial angle of 156.5° was used to distinguish left bronchus from right bronchus. The bronchial isomerism could be identified in all pathological cases by autopsy and bronchial-atrial concordance occurred in 27 pathological cases (96.4%). In 21 pathological cases, the bilateral bronchial angle was <156.5 versus >156.5 differentiated left from right isomerism, respectively. The ratio of the left/right bronchial angle of >0.935 identified 92.9% (26/28) of all pathological cases, with a sensitivity of 89.7%. Conclusions: Fetal ultrasound can detect the bronchial morphology and the presence of bronchial isomerism in fetuses with isomerism according to bronchial angles and the ratio of left/right bronchial angle.

研究目的：本研究旨在评估胎儿超声（fetal ultrasound）能否判定支气管异构症（bronchial isomerism），并区分左侧异构症与右侧异构症。
研究方法：本研究共纳入110名健康胎儿与28名罹患支气管异构症的胎儿。测量气管中线与支气管内缘之间的外侧夹角。通过支气管夹角及左/右支气管夹角比值，对支气管形态进行区分，并确认病理病例中支气管异构症的存在。
研究结果：左、右支气管的正常夹角分别为146.98°（95%置信区间：145.15~147.81°）与167.37°（95%置信区间：166.30~168.44°）。以156.5°作为支气管夹角临界值（cutoff），可区分左、右支气管。所有病理病例均可通过尸检确诊支气管异构症，其中27例病理病例存在支气管-心房一致性（bronchial-atrial concordance），占比96.4%。在21例病理病例中，双侧支气管夹角<156.5°与>156.5°者可分别被判定为左侧异构症与右侧异构症。左/右支气管夹角比值>0.935可识别出92.9%（26/28）的全部病理病例，灵敏度为89.7%。
研究结论：基于支气管夹角及左/右支气管夹角比值，胎儿超声可检测支气管形态，并确诊罹患支气管异构症的胎儿的支气管异构症情况。