Correlation between Diameter of Yolk Sac on Transvaginal Ultrasonography at 6-12 Weeks of Gestation and Adverse Pregnancy Outcomes.

Objective: To evaluate the correlation between yolk sac diameter at 6 to 12 weeks of gestation measured via transvaginal ultrasound and adverse pregnancy outcomes.

Methods: This prospective cohort study was conducted at the Ain Shams University Maternity Hospital from July 1, 2019 to January 30, 2020. It included 120 pregnant women attending the outpatient clinic at 6 to 12 weeks of gestation. Transvaginal ultrasound was performed to measure inner yolk sac diameter. Normal diameter was considered to be 2-5 mm. Cases were followed up in routine antenatal care until the 16th week of gestation.

Results: Significant associations were found between maternal age and yolk sac diameter; yolk sac diameter and early miscarriage; a high percentage of cases of positive fetal life occurred when a normal yolk sac diameter (2-5 mm) was present (p<0.001); in yolk sac diameters <2mm positive fetal life was 0.0% and negative fetal life was 42.9%; in yolk sac diameters of 2-5mm positive fetal life was 81.1% and the negative fetal life was 7.1%; and in yolk sac diameters >5mm positive fetal life was 18.9% and negative fetal life was 50.0% (p<0.001), x2 60.094; and the best cutoff value for yolk sac diameter was >0.56, with a sensitivity of 78.6%, a specificity of 84.3%.

Conclusions: We found a highly significant correlation between yolk sac diameter and early pregnancy loss.