Fetal Ultrasonic Evaluation of Bronchial Morphology in Fetuses with Isomerism

The aim of the study was to evaluate whether fetal ultrasound could determine bronchial isomerism and distinguish left isomerism from right isomerism.

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.

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%.

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.