13-14-week fetal anatomy scan: a 5-year prospective study

Area of Science:

• Medical Imaging
• Obstetrics and Gynecology
• Fetal Medicine

Background:

• First-trimester ultrasound screening is crucial for detecting fetal chromosomal abnormalities.
• Assessing fetal anatomy in the first trimester can provide early insights into potential anomalies.

Purpose of the Study:

• To evaluate the efficacy of early (first-trimester) ultrasound in detecting fetal anomalies using transabdominal (TAS) and transvaginal (TVS) sonography.
• To compare early ultrasound findings with traditional mid-trimester anomaly scans.
• To assess patient acceptance of early transvaginal sonography.

Main Methods:

• A prospective study involving 2876 pregnant women over 5 years (2002-2007).
• Initial 13-14-week ultrasound by TAS, followed by TVS if needed for complete anatomical survey.
• Comparison with mid-trimester fetal anatomy scans (n=2834).

Main Results:

• Transvaginal sonography (TVS) significantly improved visualization of fetal structures compared to transabdominal sonography (TAS) (P < 0.001).
• Complete fetal anatomical surveys were achieved in 64% of TAS vs. 82% of TVS attempts (P < 0.001).
• Early scans detected anomalies in 21 fetuses, with 14 leading to termination; mid-trimester scans identified 17 anomalies.

Conclusions:

• Early ultrasound, especially with TVS, shows potential for precise fetal anatomy visualization and anomaly detection.
• TVS can complement difficult TAS examinations, but patient acceptance varies.
• The mid-trimester scan remains essential for a comprehensive fetal anatomical survey.