The Performance of First-Trimester Anatomy Scan: A Decision Analysis

Area of Science:

• Medical Imaging
• Obstetrics
• Fetal Medicine

Background:

• First-trimester ultrasound (US) may enhance fetal anomaly detection but could increase overall US utilization.
• The utility of early anatomy assessment via first-trimester US requires careful evaluation.

Purpose of the Study:

• To assess the diagnostic utility of first-trimester ultrasound for fetal anatomy evaluation.
• To compare strategies of first- plus second-trimester US versus second-trimester US alone.

Main Methods:

• A decision analytic model was developed to compare different US screening strategies.
• The model analyzed four populations: general, normal weight, obese, and diabetic women.
• Outcomes included major structural anomalies detected, US examinations performed, and false-positive rates.

Main Results:

• Combining first- and second-trimester US detected more anomalies but increased examinations per anomaly.
• The addition of first-trimester anatomy US resulted in a slight increase in false positives (<10/10,000).
• In high-prevalence/low-sensitivity populations (diabetes, obesity), <60 additional US were needed per anomaly detected.

Conclusions:

• First-trimester ultrasound may be beneficial for anomaly detection in high-risk pregnancies.
• The strategy of adding a first-trimester anatomy scan to a second-trimester scan shows promise for improved detection in specific populations.