Blood flow redistribution in the fetal umbilical-portal venous system in pregnancy complicated by diabetes mellitus

Abstract

BACKGROUND: The fetal liver plays a central role in energy metabolism and is supplied mainly by the vessels of the umbilical-portal venous system. Redistribution of blood flow in this system is a key adaptive response of the fetus to environmental change. AIM: The aim of this study was to evaluate the hemodynamic redistribution in the fetal umbilical-portal venous system in pregnant women with pregestational diabetes mellitus, gestational diabetes mellitus and in healthy pregnant women. MATERIALS AND METHODS: This prospective cohort single-center study was conducted at the Research Institute of Obstetrics, Gynecology and Reproductology named after D.O. Ott, Saint Petersburg between February 2022 and September 2023. The study included 188 patients who made up the following comparison groups: pregestational diabetes mellitus (n = 86), gestational diabetes mellitus (n = 44), and control (n = 58). Patients underwent ultrasound from 30+0 to 41+3 weeks with assessment of venous hemodynamics in the vessels of the umbilical-portal venous system such as the umbilical vein, left portal vein, right portal vein, main portal vein, and ductus venosus. RESULTS: The umbilical vein volumetric blood flow in the I group exceeded that in the II group by 23.60 ml/min/kg and that in the control group by 30.35 ml/min/kg (p 0.001). The total liver volumetric blood flow in patients with pregestational diabetes mellitus (106.85 ml/min/kg) also exceeded that in the gestational diabetes mellitus group by 28.04 ml/min/kg and that in the control group by 33.73 ml/min/kg (p 0.001). The umbilical vein and total fetal liver blood flows increased to full-term pregnancy, but, when normalized by the estimated fetal weight, the both flows showed a downward trend at 37–41 weeks of gestation (p 0.001). No significant differences were revealed in the ductus venosus volumetric blood flow in the study groups. However, there was a significant decrease in the ductus venosus shunt fraction in patients with pregestational diabetes mellitus (16.83 %) by −8.34 % compared to the control group (24.56 %) and by −5.65 % compared to the II group (22.89 %). The downward trend persisted throughout the third trimester of pregnancy and reached its maximum at full-term (p 0.001). CONCLUSIONS: With pregestational diabetes mellitus, there is a priority redistribution of highly oxygenated blood from the umbilical vein to the right lobe of the fetal liver, accompanied by a decrease in the ductus venosus shunt fraction. This may underlie the pathogenesis of such complications as fetal macrosomia and diabetic fetopathy.