Retrospective Analysis of First-Trimester Prenatal Ultrasonographic Features in Six Fetus with Unilateral Pulmonary Agenesis.

OBJECTIVES: To investigate the ultrasonographic features of fetal unilateral pulmonary agenesis (UPA) in the first trimester. METHODS: A total of 40,259 fetuses who underwent ultrasound screening at 11-14 weeks' gestation at the Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region between January 2023 and April 2026 were included. The clinical data and the first trimester ultrasonographic features of 6 cases diagnosed with UPA were retrospectively analyzed. RESULTS: Six cases of UPA were highly suspected in the first trimester. The fetal crown-rump length (CRL) ranged from 49 to 84 mm. The nuchal translucency (NT) thickness was greater than the 95th percentile in 2 cases. Among them, 4 cases involved the right side and 2 cases involved the left side. Four cases were complicated with other morphological malformations. Chromosomal and microarray analyses were performed in 2 cases, of which 1 case was diagnosed with trisomy 16 syndrome and 1 case was normal. On transverse view of the fetal thorax with UPA, the heart shifted to the affected side and was closely attached to the chest wall in 6 fetuses. Six cases showed significant changes in the cardiac axis; the axis was approximately 0° in the 4 cases of right pulmonary agenesis (PA) and nearly 90° in the 2 cases of left PA. Pathological examination was performed in 4 cases and confirmed the prenatal ultrasound diagnosis. CONCLUSION: Fetal cardiac displacement with the "wall-hugging sign" and the displacement of the cardiac axis are the 2 reliable ultrasound signs for screening UPA in the first trimester.