Efficacy of first-trimester ultrasound parameters for prediction of early spontaneous abortion

Objective: To assess first-trimester ultrasound measurements for the prediction of early spontaneous abortion.

Methods: In a prospective observational study in Jamshedpur, India, women with singleton pregnancies of 42-76 days were enrolled between November 2014 and April 2016. Inclusion criteria were spontaneous conception, embryonic cardiac activity, and regular menstrual cycle. Fetal crown-to-rump length (CRL), gestational sac diameter (GSD), yolk sac diameter (YSD), and fetal heart rate (FHR) were measured by transvaginal ultrasonography. Ultrasonography was repeated at 12 weeks and beyond to determine pregnancy continuation.

Results: Among 800 women, 140 (17.5%) experienced early spontaneous abortion. CRL, GSD, and FHR values below the 5th percentile (odds ratio [OR] 26.48, 26.94, and 100.63, respectively), and YSD above the 95th percentile (OR 1.04) were predictors of early abortion. Normal YSD did not reduce the risk of abortion if the other three parameters were below the 5th percentile (OR 34.27). For every 10-bpm decrease in FHR below 130, there was 26.7% increased risk of abortion. GSD-CRL difference of less than 5 mm was associated with a higher likelihood of abortion (OR 4.88).

Conclusion: First-trimester ultrasound measurements are predictors of early abortion. Risk assessment tables based on combinations of abnormal measures might improve prediction rates.