Detection of fetal structural abnormalities at 20 and 30 weeks: a retrospective study of prenatal ultrasound screening.

Abstract

Purpose: To evaluate the role of ultrasound screening for fetal structural abnormalities at 20 and 30 weeks' gestation.

Methods: This retrospective study included women with singleton pregnancies who underwent routine ultrasound screening at our hospital between May 2014 and April 2021. Participants received two ultrasound screening examinations: at 20 and 30 weeks' gestation. We evaluated the frequency and details of fetal structural abnormalities identified during each examination.

Results: A total of 10,560 pregnant women underwent ultrasound screening at 20 and 30 weeks' gestation and delivered at our hospital. Structural abnormalities were observed in 142 (1.3%) women; of note, screening examinations at 20 and 30 weeks detected 42.3% and 23.9% of cases, respectively. Routine point-of-care ultrasound examinations performed between 20 and 30 weeks and beyond 30 weeks detected 8.5% and 6.3% of cases, respectively, with 19.0% of cases identified after birth. Cleft lip and palate and ventricular septal defects (VSDs) were the most common abnormalities detected at the 20-week ultrasound screening. At the 30-week ultrasound screening, in addition to hydronephrosis, VSD, and vascular rings, which were also detected at the 20-week ultrasound screening, diaphragmatic hernia, ovarian cysts, achondroplasia, duodenal atresia, and meconium peritonitis, which could be apparent later in pregnancy, were detected.

Conclusions: The 20-week ultrasound screening revealed common fetal structural abnormalities, and the 30-week ultrasound screening detected fetal structural abnormalities that failed to be detected during the 20-week ultrasound screening and became apparent later in pregnancy. Adding a 30-week ultrasound screening provides enhanced diagnostic details in comparison to 20-week screening.