Repeat Fetal Screening Ultrasounds and Abnormality Detection

Repeat ultrasound imaging during pregnancy requested because of incomplete visualization of the fetus infrequently detects abnormal fetal anatomy, according to a study published in the Journal of Ultrasound in Medicine.

Researchers from Yale University in New Haven, CT, performed a retrospective cohort study to determine how often routine fetal anatomic sonography fails to completely visualize fetal anatomy, the proportion of women with incomplete ultrasound examinations who are recommended for repeat screening and then undergo repeat sonography; and how often abnormal fetal anatomy is detected on repeat sonography.

The researchers reviewed the records of 16,300 women (mean maternal age 30.8) who were between 17 and 21 weeks’ gestation with a singleton pregnancy who presented for screening anatomic sonography. Mean gestational age was 18.8 weeks. The results showed that 2,157 of the 16,300 screening examinations (13.2%) had incomplete visualization of fetal anatomy. Of those women eligible for follow-up, 91.5% were recommended for repeat screening; 92.8% in this group did have a subsequent examination. Of 1,560 repeat screening ultrasound examinations, eight (0.5%) showed an abnormality in the components of anatomy that were previously visualized incompletely.

The researchers concluded that incomplete visualization was common in screening fetal anatomic ultrasound examinations and recommendations for repeat imaging were nearly universal, but abnormal fetal anatomy was infrequently discovered on repeat screening.