Threat of miscarriage at 10–13 weeks of gestation: Consequences and possible risks

Abstract

In press

Background. Problems during the fetal period attract our particular attention, as they prevent the second wave of cytotrophoblast invasion into the myometrial segments of the spiral arteries and contribute to the development of placental dysfunction.

Aim. To study the state of extraembryonic structures in case of miscarriage, at the fetal stage of intrauterine development of the child, at the end of the first trimester of gestation and their influence on the development of placental dysfunction.

Materials and Methods. The study included 20 patients (Group 1) with a verified threat of pregnancy termination without bleeding at the fetal stage of gestation ([10–13] weeks), 22 women with verified RetroChorial Hematoma (RСH) at the same time (Group 2) and 20 women (Control Group) with a physiological course of the first trimester of gestation. During the transvaginal ultrasound examination, the chorionic volume was calculated using a special three-dimensional program VOCAL (Virtual Organ Computer-aided AnaLysis), and its vascular system was assessed. The data are presented as Me [Q₁; Q₃]; the comparison of three groups was performed by the Kruskal–Wallis test with Dunn's post-hoc test and Bonferroni correction.

Research Ethics. The study was conducted in accordance with the principles of the World Medical Association Declaration of Helsinki (1964–2024) and approved by the Biomedical Ethics Committee of Bukovinian State Medical University (Protocol No.7 of April 17, 2025). The examination was performed only after obtaining the patient's informed consent.

Results. In the Control Group, the median chorionic volume (Vx) was 164.0 [162.5; 165.2] cm³, the Vascularization Index (VI) was 19.4 [18.3; 20.7], and the blood Flow Index (FI) was 49.2 [48.5; 50.1]. In Group 1 (threat of miscarriage without bleeding), Vx decreased to 152.1 [146.2; 156.8] cm³ (by 7.4%), VI to 13.4 [12.5; 14.3] (by 30.9%), and FI to 41.3 [39.0; 43.7] (by 16.1%). In Group 2 (threat of retrochorial hematoma), Vx decreased to 131.5 [127.1; 135.9] cm³ (by 20.1%), VI to 9.6 [8.9; 10.4] (by 50.5%), and FI to 34.1 [31.8; 36.3] (by 30.7%). All differences were statistically significant (Kruskal–Wallis test with Dunn’s post-hoc and Bonferroni correction, adjusted p<0.01 for Group 1 vs. Control Group, and p<0.001 for Group 2 vs. Control Group as well as p<0.01 for Group 1 vs. Group 2).

Conclusions. Retrochorionic hematomas formed at the risk of miscarriage at [10–13] weeks of gestation are a direct cause of chorionic hypoplasia and impaired chorionic maturation. A decrease in the index of vascularization and blood flow in the chorion creates a high risk of placental dysfunction, which in turn worsens the prognosis of further pregnancy.

Keywords: obstetrics, placenta, angiogenesis, ultrasonography, obstetric hemorrhage, trophoblast.