Harmony Behind the Trumped-Shaped Vessel: the Essential Role of the Ductus Venosus in Fetal Medicine

Regional differences in the umbilical vein and ductus venosus at different stages of normal human development

During the fetal period, oxygenated blood from the placenta flows through the umbilical vein (UV), portal sinus, ductus venosus (DV), and inferior vena cava (IVC) to the heart. This venous route varies regionally in many aspects. Herein, we sought to characterize the venous route's morphological features and regional differences during embryonic and early-fetal periods. Twenty-nine specimens were selected for high-resolution digitized imaging; 18 embryos were chosen for histological analysis. The venous route showed a primitive, large, S-shaped curved morphology with regional narrowing and dilation at Carnegie stage (CS) 15. Regional differences in vessel-wall differentiation became apparent from approximately CS20. The vessel wall was poorly developed in most DV parts; local vessel-wall thickness at the inlet was first detected at CS20. The lumen of the venous route changed from a nonuniform shape to a relatively round and uniform morphology after CS21. During the early-fetal period, two large bends were observed around the passage of the umbilical ring and at the inlet of the liver. The length ratio of the extrahepatic UV to the total venous route increased. The sectional area gradually increased during embryonic development, whereas differences in sectional area between the DV, UV, and IVC became more pronounced in the early-fetal period. Furthermore, differences in the sectional area between the narrowest part of the DV and other hepatic veins and the transverse sinus became more pronounced. In summary, the present study described morphological, morphometric, and histological changes in the venous route throughout embryonic and early-fetal development, clarifying regional characteristics.

Does abnormal ductus venosus pulsatility index at the first-trimester effect on adverse pregnancy outcomes?

AIM

The ductus venosus pulsatility index for veins (DV PIV) has become a popular marker of the first-trimester scan. The aim of this study is to search for any difference between groups with normal and abnormal DV PIV values in terms of adverse pregnancy outcomes.

METHODS

We retrospectively evaluated 556 women whose first-trimester scan was performed. The ductus venosus pulsatility indices were examined at singleton pregnancies between 11 and 14 weeks of gestation. Patients were categorized as Group-I with normal DV PIV (DV PIV ≥ 0.73, ≤1.22) and as Group-II with abnormal DV PIV. Group-II was subgrouped as Group-IIA which composed of patients with DV PIV < 0.73 and as Group-IIB with DV PIV > 1.22.

RESULTS

There were 451 subjects in Group-I and 105 subjects in Group-II (Group-IIA = 32 and Group-IIB = 73). The comparisons between major groups revealed a statistically significant increase about miscarriage (p = 0.002), stillbirth (p < 0.001), small for gestational age (p = 0.033), low birth weight (p < 0.001), fetal growth restriction (p = 0.048), and major congenital heart defect (p=<0.001) in Group-II. This difference is mainly due to Group-IIB. There is no difference in preterm delivery, preeclampsia and gestational diabetes between Group I and II.

CONCLUSION

Routinely monitoring DIV PIV as a first-trimester screening should provide valuable information regarding adverse pregnancy outcomes such as miscarriage, stillbirth, small for gestational age, low birth weight, fetal growth restriction and major congenital heart defect.

Skeletal Muscle Damage in Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR) represents a rate of fetal growth that is less than average for the population and the growth potential of a specific infant. IUGR produces infants who are small for gestational age (SGA) but also appropriate for gestational age (AGA). It refers to growth less than expected for gestational age and is most often under 10th percentiles for age. It develops during the late second and third trimesters of gestation. The etiology of IUGR is multifactorial. One of the most important factors which leads to IUGR is a decrease of nutrients and oxygen delivered to the fetus by the placenta. The growth of adipose tissue and skeletal muscle is limited by the declined fetal nutrient supply later in gestation. IUGR affects about 24% of babies born in developing countries. Worldwide, IUGR is the second cause of perinatal morbidity and mortality behind the premature birth and a major predisposing factor to metabolic disorders throughout postnatal life, even at adult age. Skeletal muscle represents about 35-40% of the body mass and plays an essential role in metabolic homeostasis, being responsible for 65% of fetal glucose consumption. A reduction in skeletal muscle growth characterizes IUGR fetuses compared to normal weight neonates. The decrease in muscle mass is not compensated after birth and persists until adulthood. This is a review of the literature, a neonatological, clinical point of view on the effects of IUGR on striated muscles. The available studies on this subject are currently the results of experimental research on animals, and information about the human fetus and newborn are scarce.