Heart Activity Visualization in Embryos with Crown-Rump Length Shorter Than 5 mm and Its Role in Prediction of Early Pregnancy Failure in Patients of Recurrent Early Pregnancy Loss

Abstract

Background: Previously, only embryos with a crown-rump length (CRL) of ≥5 mm could have their heart activity seen using  ultrasonography. However, due to advancements in ultrasound resolution, viable embryos with CRL as small as 2 mm may now be  diagnosed. 

Objective: The current study aimed to investigate whether early embryonic heart rate (EHR) in embryos with smaller CRL may  be used as a predictor of pregnancy outcome. 

Methods: This prospective cohort study included 78 cases, from June 2023 to May 2024. All  women had a history of recurrent pregnancy. Early transvaginal ultrasound was done with EHR and was assessed using M-mode. Follow- up was done to determine the outcome of the pregnancy after 12 weeks. The negative outcome manifested as a spontaneous pregnancy  loss that transpired at or prior to 12 weeks of gestation. 

Results: A normal CRL diameter was present in 79.6% of the CRL in the examined  groups. With cases of normal diameter that ended in miscarriage, only one had a CRL that lasted past the first trimester. With  a total accuracy of 99.1%, CRL's sensitivity and specificity for miscarriage prediction were 98.6% and 100%, respectively. With a total  accuracy of 98.1%, When anticipating a first-trimester pregnancy outcome, EHR's overall accuracy was 98.2%, with specificity of 100% and sensitivity of 97.4%. 

Conclusion: These days, most embryos with a CRL of 2 to 5 mm can show cardiac activity. About 80% of the time,  non-visualization at this point is linked to embryonic death. A poor pregnancy outcome is linked to both embryonic bradycardia and small  CRL.