The fetal anomaly screening scan: an international perspective

Abstract

Fetal structural anomalies, affecting up to 3% of pregnancies, can be a major concern for expectant parents. Ultrasound screening has become an essential part of prenatal care, offering early detection of birth defects and empowering parents with information for reproductive decision making. While first-trimester scans are becoming more informative, the second-trimester scan remains the cornerstone of anomaly detection. Technological advancements, and the use of additional tools like MRI, are further enhancing our ability to ensure a healthy outcome for both mother and baby. Advancements have enabled detection of around half of all major anomalies in the first trimester (11–13+6) weeks. Professional societies recommend the second-trimester anatomy scan (18–22 weeks) as the gold standard for anomaly detection. The fetal anomaly scan boasts a high detection rate for major structural malformations, ranging from 15% to exceeding 90% in some cases. Detection rates vary depending on the organ system being examined. Equipment settings and sonographer experience play a role in accuracy. Whilst not 100% effective, the scan is safe and valuable. It empowers informed decision-making and can improve some pregnancy outcomes by enabling early detection and management. This allows for interventions, planning for delivery at the right time and place, and emotional preparation for parents. However, it is crucial to understand the limitations of the scan and the possibility of false positives or missed anomalies.