BackgroundThe diagnosis of congenital intrathoracic lesions still has limitations. The airway development was influenced by intrathoracic factors. Whether the diagnostic value of the upper airway parameters in congenital intrathoracic lesions has not been confirmed.ObjectivesWe aimed to compare fetal upper airway parameters between normal fetuses and fetuses with intrathoracic lesions, and we tried to verify its diagnostic value in intrathoracic lesions.MethodsThis was an observational case–control study. In the control group, 77 women were screened at 20–24 weeks’ gestational age, 23 were screened at 24–28 weeks’ gestational age, and 27 were screened at 28–34 weeks’ gestational age. In the case group, 41 cases were enrolled (6 cases of intrathoracic bronchopulmonary sequestration, 22 of congenital pulmonary airway malformations, and 13 of congenital diaphragmatic hernia). Fetal upper airway parameters (tracheal width, the narrowest lumen width, and width of the subglottic cavity and laryngeal vestibule) were measured using ultrasound equipment. The correlations between fetal upper airway parameters and gestational age, and the differences in fetal upper airway parameters between cases and controls, were analyzed. The standardized airway paraments were acquired, and their potential diagnostic value for congenital intrathoracic lesions were analyzed.ResultsThe fetal upper airway parameters of both groups were positively correlated with the gestational age: The control group, tracheal width (R2= 0.569,p< 0.001), narrowest lumen width (R2= 0.429,p< 0.001), subglottic cavity width (R2= 0.551,p< 0.001), laryngeal vestibule width (R2= 0.349,p< 0.001). The case group (tracheal widthR2= 0.474,p< 0.001) narrowest lumen width (R2= 0.425,p< 0.001), subglottic cavity width (R2= 0.623,p< 0.001), laryngeal vestibule width (R2= 0.347,p< 0.001). Fetal upper airway parameters of the cases group were smaller than those of the controls group. The tracheal width in fetuses with congenital diaphragmatic hernia was the smallest among the other case groups studied. The standardized tracheal width has the best diagnostic value for congenital intrathoracic lesions in the standardized airway paraments (the area under the ROC curve was 0.894), and has a high diagnostic value for congenital pulmonary airway malformations and congenital diaphragmatic hernia (the area under the ROC curve was 0.911 and 0.992, respectively).ConclusionFetal upper airway parameters differ between normal fetuses and fetuses with intrathoracic lesions, and might offer potential diagnostic clues for congenital intrathoracic lesions.