Ultrasound useful in assessing spontaneous abortion risk after embryo transfer

Key takeaways:

• Vaginal bleeding and absent fetal heart rate with fetal pole increased spontaneous abortion risk.
• Bleeding, absent fetal heart rate and absent fetal pole were linked to highest spontaneous abortion incidence.

Women who undergo embryo transfer and have symptoms of vaginal bleeding should be assessed for risk for spontaneous abortion through pregnancy ultrasound, researchers reported in American Journal of Obstetrics & Gynecology.

“Understanding how the risk of spontaneous abortion in the setting of first trimester bleeding is affected when concurrent ultrasound measurements are included would help providers in clinical decision-making and give providers additional confidence in interpreting symptoms and guiding patient expectations,” Meridith P. Pollie, MD, a resident in the department of obstetrics and gynecology at Penn Medicine at the University of Pennsylvania Health System, and colleagues wrote. “Therefore, the objective of this study was to evaluate the risk of spontaneous abortion when combining the presence of early pregnancy bleeding with first trimester ultrasound measurements among patients with a history of infertility.”

Pollie and colleagues conducted a retrospective cohort study of 1,858 women with infertility who underwent autologous embryo transfer leading to a singleton intrauterine pregnancy from 2017 to 2019. Researchers recorded symptoms of bleeding or spotting that occurred prior to 8 weeks gestation and crown-rump length and fetal heart rate measurements at 6 and 7 weeks gestation.

Overall, there were 359 spontaneous abortions and 1,499 live births in the cohort, with 17% of women reporting vaginal bleeding. Women with both bleeding and absent fetal heart rate with fetal pole on ultrasound had a significantly increased risk for spontaneous abortion compared with women without (60% vs. 9.5%; RR = 5.36; 95% CI, 3.36-8.55). Researchers also observed the highest spontaneous abortion incidence among women with bleeding and absent fetal heart rate and absent fetal pole (95.8% vs. 9.5%; RR = 9.67; 95% CI, 7.45-12.56).

In addition, women with bleeding and either low fetal heart rate or low crown-rump length had a significantly increased risk for spontaneous abortion at 7 weeks gestation (23.1% vs. 5.1%; RR = 5.09; 95% CI, 1.83-14.19). Women with bleeding and both abnormally low fetal heart rate and crown-rump length had the highest spontaneous abortion risk compared with women without bleeding with normal ultrasound measurements (84.2% vs. 5.1%; RR = 14.82; 95% CI, 10.54-20.83).

When considering vaginal bleeding symptoms combined with ultrasound parameters, women with bleeding and normal ultrasound measurements had a similar spontaneous abortion risk compared with women without bleeding with normal ultrasound measurements at 6 (9.7% vs. 9.5%; RR = 1.05; 95% CI, 0.61-1.78) and 7 weeks gestation (3.9% vs. 5.1%: RR = 0.8; 95% CI, 0.36-1.74). Live birth rate was comparable to that of women with no bleeding and normal ultrasound measurements, the researchers wrote.

“These data can be used to reassure patients with symptoms of vaginal bleeding who present with normal ultrasound measurements, as well as to identify and guide counseling for patients with abnormal sonographic measurements who may be at increased risk for spontaneous abortion,” they wrote.