Umbilical cord morphologic characteristics and umbilical artery Doppler parameters in intrauterine growth-restricted fetuses

Exosome miRNA Expression in Umbilical Cord Blood of High-Parity Sows Regulates Their Reproductive Potential

The objective of modern pig breeding is to improve the genetic reproduction performance potential of sows, including the litter size and weight of piglets. During the gestation period, the umbilical cord facilitates placenta−fetal communication; thus, it plays an indispensable role in intrauterine embryonic development and fitness. Herein, we analyzed the molecular mechanism in declining reproductive potential in high-parity sows by assessing the changes in the umbilical cord blood. Firstly, we analyzed the reproductive characteristics data of sows, followed by histological analysis of the umbilical cord phenotype. Next, we evaluated the effect of umbilical cord blood exosomes (UCB-EXO) on angiogenesis. Finally, the miRNA expression in UCB-EXO from high-parity sows with poor reproductive performance (OS) and multiparous sows with excellent reproductive performance (MS) was assessed. Overall, the best reproductive performance was at parity 3−7, gradually decreasing after parity 8 and angiogenesis was repressed in OS. However, exosomes derived from MS (Exo-MS) exhibited pro-angiogenesis properties but were diminished in exosomes derived from OS (Exo-OS). Additionally, the angiogenesis of sows was significantly decreased, increasing the risk of disease with the increase in parity, greatly limiting the reproductive potential of the sows. At the same time, miR-188-5p expression in Exo-OS was significantly higher than in Exo-MS (p < 0.01), implying that it may play an important role in regulating the lifespan and reproductive potential of sows. These findings demonstrated that miRNAs in UCB-EXO play a central role in intrauterine development. Further, the findings suggest novel insights on reproductive potential, which provide a reference for increasing the sow reproductive efficiency.

Proteomic analysis of the umbilical cord in fetal growth restriction and preeclampsia

Fetal growth restriction (FGR) is associated with adverse perinatal outcomes. Pre-eclampsia (PreE) increases the associated perinatal morbidity and mortality. The structure of the umbilical cord in the setting of FGR and PreE is understudied. This study aimed to examine changes in the umbilical cord (UC) composition in pregnancies complicated by FGR and FGR with PreE. UC from gestational age-matched pregnancies with isolated FGR (n = 5), FGR+PreE (n = 5) and controls (n = 5) were collected, and a portion of the UC was processed for histologic and proteomic analysis. Manual segmentation analysis was performed to measure cross-section analysis of umbilical cord regions. Wharton’s Jelly samples were analyzed on a tims-TOF Pro. Spectral count and ion abundance data were analyzed, creating an intersection dataset from multiple mass spectrometry search and inference engines. UCs from FGR and FGR with PreE had lower cross-sectional area and Wharton’s Jelly area compared with control (p = 0.03). When comparing FGR to control, 28 proteins were significantly different in abundance analysis and 34 in spectral count analysis (p < 0.05). Differential expression analysis between PreE with FGR vs controls demonstrated that 48 proteins were significantly different in abundance and 5 in spectral count. The majority of changes occurred in proteins associated with extracellular matrix, cellular process, inflammatory, and angiogenesis pathways. The structure and composition of the UC is altered in pregnancies with FGR and FGR with PreE. Future work in validating these proteomic differences will enable identification of therapeutic targets for FGR and FGR with PreE.

Occupational Exposure to Ultrafine Particles and Placental Histopathological Lesions: A Retrospective Study about 130 Cases

Ultrafine particles (UFPs) are particles smaller than 100 nanometers that are produced unintentionally during human activities or natural phenomena. They have a higher biological reactivity than bigger particles and can reach the placenta after maternal exposure. One study has shown an association between maternal occupational exposure to UFPs and fetal growth restriction. Yet few studies have focused on the effects of UFP exposure on placental histopathological lesions. The aim of this study was to investigate the association between maternal occupational exposure to UFPs and histopathological lesions of their placenta. The analyses were based on data from the ARTEMIS Center. A job-exposure matrix was used to assess occupational exposure to UFPs. The histopathological placental exam was performed by two pathologists who were blinded to the exposure of each subject. The examination was conducted in accordance with the recommendations of the Amsterdam consensus. The study sample included 130 placentas (30 exposed, 100 unexposed). Maternal occupational exposure to UFPs during pregnancy is significantly associated with placental hypoplasia (the phenomenon affected 61% of the exposed patients and 34% of the unexposed ones, p < 0.01). Further research is needed to explain its pathophysiological mechanisms.

Stereological and Histological Assessment of the Umbilical Cord in New-Born Rat

Background

Umbilical cord plays a crucial role in the continuation of pregnancy by transferring nutrition and oxygen across the placenta to the fetus. We aimed to investigate the morphometrical and histological features of the umbilical cords in new-born rats.

Materials and Methods

The adult male and female rats were chosen for matting purpose in the present study. Briefly, ten adult Wistar albino rats (female, n = 5; male, n = 5) were randomly assigned into five groups of two animals (female, n = 1; male, n = 1). Immediately after parturition, two umbilical cords of new-born rats (0-day-old) from each group were randomly selected. Finally, ten umbilical cord samples were examined using the histological and stereological methods in the light and electron microscopes.

Results

The total numbers of Hofbauer cells and mesenchymal stromal cells was estimated statistically. We also calculated the mean volume of umbilical cords, arteries and veins, as well as arterial and venous lumens. Our histological findings also exhibited the histological features of Hofbauer cells, mesenchymal stromal cell cells, and blood vessels.

Conclusion

Our findings showed more detailed information about umbilical cord tissues and their components, and that may contribute to the diagnose of umbilical cord complications in the developing fetus.

Current Perspectives of Prenatal Sonography of Umbilical Cord Morphology

The umbilical cord constitutes a continuation of the fetal cardiovascular system anatomically bridging between the placenta and the fetus. This structure, critical in human development, enables mobility of the developing fetus within the gestational sac in contrast to the placenta, which is anchored to the uterine wall. The umbilical cord is protected by unique, robust anatomical features, which include: length of the umbilical cord, Wharton’s jelly, two umbilical arteries, coiling, and suspension in amniotic fluid. These features all contribute to protect and buffer this essential structure from potential detrimental twisting, shearing, torsion, and compression forces throughout gestation, and specifically during labor and delivery. The arterial components of the umbilical cord are further protected by the presence of Hyrtl’s anastomosis between the two respective umbilical arteries. Abnormalities of the umbilical cord are uncommon yet include excessively long or short cords, hyper or hypocoiling, cysts, single umbilical artery, supernumerary vessels, rarely an absent umbilical cord, stricture, furcate and velamentous insertions (including vasa previa), umbilical vein and arterial thrombosis, umbilical artery aneurysm, hematomas, and tumors (including hemangioma angiomyxoma and teratoma). This commentary will address current perspectives of prenatal sonography of the umbilical cord, including structural anomalies and the potential impact of future imaging technologies.

A Review of Biomechanics Analysis of the Umbilical-Placenta System With Regards to Diseases

Placenta is an important organ that is crucial for both fetal and maternal health. Abnormalities of the placenta, such as during intrauterine growth restriction (IUGR) and pre-eclampsia (PE) are common, and an improved understanding of these diseases is needed to improve medical care. Biomechanics analysis of the placenta is an under-explored area of investigation, which has demonstrated usefulness in contributing to our understanding of the placenta physiology. In this review, we introduce fundamental biomechanics concepts and discuss the findings of biomechanical analysis of the placenta and umbilical cord, including both tissue biomechanics and biofluid mechanics. The biomechanics of placenta ultrasound elastography and its potential in improving clinical detection of placenta diseases are also discussed. Finally, potential future work is listed.

Novel insights for the role of nitric oxide in placental vascular function during and beyond pregnancy

More than 30 years have passed since endothelial nitric oxide synthesis was described using the umbilical artery and vein endothelium. That seminal report set the cornerstone for unveiling the molecular aspects of endothelial function. In parallel, the understanding of placental physiology has gained growing interest, due to its crucial role in intrauterine development, with considerable long-term health consequences. This review discusses the evidence for nitric oxide (NO) as a critical player of placental development and function, with a special focus on endothelial nitric oxide synthase (eNOS) vascular effects. Also, the regulation of eNOS-dependent vascular responses in normal pregnancy and pregnancy-related diseases and their impact on prenatal and postnatal vascular health are discussed. Recent and compelling evidence has reinforced that eNOS regulation results from a complex network of processes, with novel data concerning mechanisms such as mechano-sensing, epigenetic, posttranslational modifications, and the expression of NO- and l-arginine-related pathways. In this regard, most of these mechanisms are expressed in an arterial-venous-specific manner and reflect traits of the fetal systemic circulation. Several studies using umbilical endothelial cells are not aimed to understand placental function but general endothelial function, reinforcing the influence of the placenta on general knowledge in physiology.

Current Perspectives of Prenatal Sonographic Diagnosis and Clinical Management Challenges of Nuchal Cord(s)

Umbilical cord accidents preceding labor are uncommon. In contrast, nuchal cords are a very common finding at delivery, with reported incidences of a single nuchal cord of approximately between 20% and 35% of all singleton deliveries at term. Multiple loops occur less frequently, with reported incidence rates inverse to the number of nuchal cords involved. Rare cases of up to 10 loops of nuchal cord have been reported. While true knots of the umbilical cord have been associated with a 4–10-fold increased risk of stillbirth, nuchal cord(s) are most often noted at delivery of non-hypoxic non-acidotic newborns, without any evidence of subsequent adverse neonatal outcome. Prior to ultrasound, nuchal cords were suspected clinically following subtle (spontaneous or evoked) electronic fetal heart rate changes. Prenatal sonographic diagnosis, initially limited to real-time gray-scale ultrasound, currently entails additional sonographic modalities, including color Doppler, power Doppler, and three-dimensional sonography, which have enabled increasingly more accurate prenatal sonographic diagnoses of nuchal cord(s). In contrast to true knots of the umbilical cord (which are often missed at sonography, reflecting the inability to visualize the entire umbilical cord, and hence are often incidental findings at delivery), nuchal cord(s), reflecting their well-defined and sonographically accessible anatomical location (the fetal neck), lend themselves with relative ease to prenatal sonographic diagnosis, with increasingly high sensitivity and specificity rates. While current literature supports that single (and possibly double) nuchal cords are not associated with increased adverse perinatal outcome, emerging literature suggests that cases of ≥3 loops of nuchal cords or in the presence of a coexisting true knot of the umbilicus may be associated with an increased risk of stillbirth or compromised neonatal status at delivery. This commentary will address current perspectives of prenatal sonographic diagnosis and clinical management challenges associated with nuchal cord(s) in singleton pregnancies.

The Pro-angiogenesis Of Exosomes Derived From Umbilical Cord Blood Of Intrauterine Growth Restriction Pigs Was Repressed Associated With MiRNAs

Dysfunctional umbilical cord blood (UCB) is a key factor for the development of intrauterine growth restriction (IUGR) in utero. Poor degrees of angiogenesis were observed during IUGR development. Here, it was demonstrated that NV-EXO (normal piglet's Umbilical Veins derived exosomes) promoted angiogenesis within the subdued pro-angiogenesis context of IV-EXO (IUGR piglet's Umbilical Veins derived exosomes). Investigation of the miRNA transcriptome of umbilical cord vein and artery exosomes between IUGR and normal littermates showed significant differences between umbilical veins from normal (NV) and IUGR (IV) piglets. Similar patterns were observed in normal (NA) and IUGR (IA) umbilical arteries as well. Moreover, the miRNAs expession level was more stable in NV. Further analysis revealed that miRNAs related to angiogenesis exhibited aberrant expression in IUGR pigs. The miRNA expression patterns between IUGR and normal piglets showed great difference. Expression of miR-150 in the tissues and UCB exosomes of IUGR pigs was significantly decreased. Up-regulation of miR-150 was able to increase proliferation, migration and tube formation of Human umbilical vein endothelial cells (HUVECs), suggesting a pro-angiogenic role. Furthermore, the data demonstrated that UCB derived miRNAs participate in fetal epigenetic regulation during pregnancy, suggesting a novel possible explanation for abnormal embryologic vascular development and several congenital cardiovascular diseases.

Morphological and structural changes of umbilical veins and clinical significance in preeclampsia

OBJECTIVE

Preeclampsia is a common complication of pregnancy that is characterized by high blood pressure. Preeclampsia can have both negative maternal and fetal effects, including impaired fetal development from reduced placental perfusion. Because umbilical vessels provide fetal blood supply, morphological changes in these vessels can critically affect fetal function. This study investigated morphological and structural changes in umbilical veins from 17 controls and 19 preeclampsia cases.

METHODS

36 umbilical cords were collected, and take umbilical cord of placental, middle, and fetal segment to H&E and orange G staining. Microscope images were obtained by digital microscope, and wall thickness, lumen diameter, wall-luminal ratio and tunica media thickness, Area of smooth muscle, area of nuclei, nuclei density, and nuclear area density of smooth muscle in tunica media were tested by Image-pro Plus.

RESULTS

Lumen diameter of umbilical veins gradually decreased, while wall thickness, tunica media thickness, and wall-luminal ratio gradually increased, from placental to fetal segments of umbilical veins. Area of smooth muscle, area of nuclei, nuclei density, and nuclear area density did not significantly differ from placental to fetal segments of umbilical veins. Compared to controls, (1) Preeclampsia cases had a smaller lumen diameter and greater wall thickness, tunica media thickness, wall-luminal ratio; (2) Preeclampsia cases had higher nuclei density and nuclear area density, and had no difference in area of smooth muscle and area of nuclei. In fetal segments of umbilical veins from preeclampsia cases, correlation analysis showed that wall-luminal ratio negatively correlated with gestation age, birth weight, and Apgar score.

CONCLUSIONS

These results indicate that umbilical vein of preeclampsia cases has a thickened tunica media from smooth muscle proliferation, which may be an adapted reaction to hypertension. Altogether, this study demonstrates that morphological changes in umbilical veins adversely affect fetal development in preeclampsia cases.

Reference ranges for the intra-amniotic umbilical cord vein diameter, peak velocity and blood flow in a regional NSW population

AIM

To construct gestational age (GA)-related reference ranges of the intra-amniotic umbilical cord vein (UCV) diameter, peak velocity (PV) and blood flow (Qucv) using a Central West New South Wales population.

MATERIALS AND METHODS

This was a prospective, quasi-experimental study of low risk, singleton pregnancies (n = 321) between 16 and 42 weeks of gestation. Participation was voluntary following informed consent. The UCV diameter and PV were measured using B mode and duplex Doppler respectively, and Qucv calculated. Percentile values and reference range graphs were established using quantile regression modelling in R statistical software. Intraclass correlation coefficients (ICCs) were calculated to assess the intra and intersonographer reliability.

RESULTS

Reference ranges for the UCV diameter, PV and Qucv were established and graphed. All three UCV measurements increased with advancing GA, with both diameter and Qucv exhibiting a decline in the late third trimester. The intrasonographer and intersonographer ICCs for the UCV diameter and PV showed almost perfect agreement within and between sonographers.

CONCLUSION

Gestational age-related reference ranges for the UCV diameter, PV and Qucv were developed using quantile regression from a cohort of low risk, singleton pregnancies in Central West NSW. These reference ranges have the potential to assist in the diagnosis and monitoring of fetal growth restriction.

Umbilical artery histomorphometry: a link between the intrauterine environment and kidney development

Prematurity is a risk factor for hypertension, vascular stiffness, nephron deficit and adult onset cardiorenal disease. The vascular tree and kidneys share morphogenic drivers that promote maturation in utero before 36 weeks of gestation. Vascular elastin accrual terminates after birth leaving collagen to promote vascular stiffness. Our objective was to determine if the histomorphometry of the umbilical artery, an extension of the aorta, parallels nephron mass across gestational age groups. From a cohort of 54 newborns, 32 umbilical cord specimens were adequate for evaluation. The umbilical cord was sectioned, stained with trichrome, and digitalized. Muscular and collagenous areas of the umbilical artery were measured in pixels using the Image J 1.48q software. Total kidney volume was measured by ultrasound and factored by body surface area (TKV/BSA). The umbilical artery total area was significantly greater in term v. preterm infants (9.3±1.3 v. 7.0±2.0 mm2; P<0.05) and increased with gestational age; while the percent muscular and collagen areas were independent of gestational age (R 2=0.04; P=ns). Percent muscular area correlated positively with TKV/BSA (r=0.53; P=0.002); while an increase in collagen correlated inversely with kidney mass (r=-0.53; P=0.002). In conclusion, an enhanced % muscular area and presumed vascular elasticity was associated with increased renal mass in all infants. Umbilical artery histomorphometry provides a link between the intrauterine environment, vascular and kidney development.

Lean Umbilical Cord - a Case Report

The "lean" umbilical cord (also known as thin-cord syndrome) is a comparatively rare anomaly of the umbilical cord, which has seldom been described in the medical literature. We report on a 35-year-old women who presented to us at 29 + 4 weeks gestation with vaginal bleeding and cervical incompetence subsequently complicated not only by premature rupture of membranes but also acute placental insufficiency requiring emergency caesarean section under general anaesthesia at 31 + 2 weeks gestation. At surgery no obvious cause for the acute placental insufficiency - such as placental abruption, cord prolapse or true knot of the umbilical cord - was found. Other possible causes such as vasa praevia or placenta praevia had previously been excluded sonographically on admission for vaginal bleeding. The only notable intraoperative finding was a macroscopically extremely thin umbilical cord.

The structural and functional effects of fine particulate matter from cooking oil fumes on rat umbilical cord blood vessels

A growing body of epidemiological evidence has supported the association between maternal exposure to airborne fine particulate matter (PM2.5) during pregnancy and adverse pregnancy outcomes. However, the specific biological mechanisms implicated in the causes of adverse pregnancy outcomes are not well defined. In this study, a pregnant rat model of exposure to different doses of cooking oil fumes (COFs)-derived PM2.5 by tail intravenous injection in different pregnant stages was established. The results indicated that exposure to COFs-derived PM2.5 was associated with adverse pregnancy outcomes, changed the structure of umbilical cord blood vessels, decreased the diameter and lumen area, and increased wall thickness. What's more, a significant increase of maximum contraction tension was observed in the early pregnancy high-dose exposure group and pregnant low-dose exposure group compared to the control group. Based on the maximum contraction tension, acetylcholine (ACh) did not induce vasodilation but caused a dose-dependent constriction, and there were significant differences in the two groups compared to the control group. Exposure to COFs-derived PM2.5 impaired the vasomotor function of umbilical veins by affecting the expression of NO and ET-1. This is the first study that evaluated the association of risk of adverse pregnancy outcomes and pregnant rats exposed to COFs-derived PM2.5 and primarily explored the potential mechanisms of umbilical cord blood vessels injury on a rat model. More detailed vitro and vivo studies are needed to further explore the mechanism in the future.

Sampling and Definitions of Placental Lesions: Amsterdam Placental Workshop Group Consensus Statement

CONTEXT

-The value of placental examination in investigations of adverse pregnancy outcomes may be compromised by sampling and definition differences between laboratories.

OBJECTIVE

-To establish an agreed-upon protocol for sampling the placenta, and for diagnostic criteria for placental lesions. Recommendations would cover reporting placentas in tertiary centers as well as in community hospitals and district general hospitals, and are also relevant to the scientific research community.

DATA SOURCES

-Areas of controversy or uncertainty were explored prior to a 1-day meeting where placental and perinatal pathologists, and maternal-fetal medicine specialists discussed available evidence and subsequently reached consensus where possible.

CONCLUSIONS

-The group agreed on sets of uniform sampling criteria, placental gross descriptors, pathologic terminologies, and diagnostic criteria. The terminology and microscopic descriptions for maternal vascular malperfusion, fetal vascular malperfusion, delayed villous maturation, patterns of ascending intrauterine infection, and villitis of unknown etiology were agreed upon. Topics requiring further discussion were highlighted. Ongoing developments in our understanding of the pathology of the placenta, scientific bases of the maternofetoplacental triad, and evolution of the clinical significance of defined lesions may necessitate further refinements of these consensus guidelines. The proposed structure will assist in international comparability of clinicopathologic and scientific studies and assist in refining the significance of lesions associated with adverse pregnancy and later health outcomes.

Role of nitric oxide in placental vascular development and function

Nitric oxide (NO) is one of the most pleiotropic signaling molecules at systemic and cellular levels, participating in vascular tone regulation, cellular respiration, proliferation, apoptosis and gene expression. Indeed NO actively participates in trophoblast invasion, placental development and represents the main vasodilator in this tissue. Despite the large number of studies addressing the role of NO in the placenta, its participation in placental vascular development and the effect of altered levels of NO on placental function remains to be clarified. This review draws a time-line of the participation of NO throughout placental vascular development, from the differentiation of vascular precursors to the consolidation of vascular function are considered. The influence of NO on cell types involved in the origin of the placental vasculature and the expression and function of the nitric oxide synthases (NOS) throughout pregnancy are described. The developmental processes involved in the placental vascular bed are considered, such as the participation of NO in placental vasculogenesis and angiogenesis through VEGF and Angiopoietin signaling molecules. The role of NO in vascular function once the placental vascular tree has developed, in normal pregnancy as well as in pregnancy-related diseases, is then discussed.

Estrogen receptor-beta mediates cyclooxygenase-2 expression and vascular prostanoid levels in human placental villous endothelial cells

OBJECTIVE

Regulation of fetoplacental blood flow is likely mediated by factors such as prostanoids. Estrogen and its receptors affect prostanoid biosynthesis. Previously, we demonstrated that villous endothelial cells express estrogen receptor-beta (ESR2), and we sought to determine its role in the mediation of fetoplacental vascular function.

STUDY DESIGN

Villous endothelial cells from uncomplicated pregnancies were isolated, cultured, and treated with estrogen. RNA interference, real-time polymerase chain reaction, Western blotting, and enzyme immunoassays were performed.

RESULTS

Cyclooxygenase-2 (COX-2) expression levels were not altered consistently by estrogen. RNA interference of ESR2 led to a concomitant decrease in COX-2 messenger RNA (P < .0001) and protein (P < .05) in the presence and absence of estradiol. ESR2 knock-down also led to diminished prostacyclin and thromboxane concentrations in the absence of estradiol (P < .005).

CONCLUSION

ESR2 mediates COX-2 expression levels and both prostacyclin and thromboxane concentrations in the basal state, which suggests the possibility of ligand-independent regulation of COX-2 activity and prostaglandin H2 substrate availability. Further investigation regarding ESR2 regulation of prostanoid biosynthesis and its effects on the fetoplacental vasculature is warranted.

Umbilical cord thickness in the first and early second trimesters and perinatal outcome

OBJECTIVES

To study the association between thickness of the umbilical cord at 11+0 to 14+6 gestational weeks and perinatal outcome.

METHODS

We studied 216 pregnant women between 11+0 and 14+6 weeks' gestation with singletons, intact membranes, normal volumes of amniotic fluid and a regular menstrual period. Patients with umbilical cord measurements below the 5(th) centile were defined as thin umbilical cord group and those between the 5(th) and 95(th) or above 95(th) centile were defined as non-lean umbilical cord group. Abortion or fetal demise, preeclampsia, mode of delivery, gestational age at delivery, birth weight, and 5-min Apgar scores were noted.

RESULTS

A statistically significant difference existed between the mean gestational age, mode of delivery, birth weight and adverse perinatal outcome of the two groups. The relative risk of the adverse perinatal outcome in lean umbilical cords was 6.92 (2.71-17.67; 95% CI). The umbilical cord thickness correlated with birth weight (P<0.05).

CONCLUSIONS

Sonographic finding of a lean umbilical cord at 11+0 to 14+6 weeks' gestation should prompt the physician to strict monitoring of pregnancy.

Fetal environment

The intrauterine environment has a strong influence on pregnancy outcome. The placenta and the umbilical cord together form the main supply line of the fetus. Amniotic fluid also serves important functions. These three main components decide whether there will be an uneventful pregnancy and the successful birth of a healthy baby. An insult to the intrauterine environment has an impact on the programming of the fetus, which can become evident in later life, mainly in the form of cardiovascular diseases, diabetes, and certain learning disabilities. The past two decades have witnessed major contributions from researchers in this field, who have included ultrasonologists, epidemiologists, neonatologists, and pediatricians. Besides being responsible for these delayed postnatal effects, abnormalities of the placenta, umbilical cord, and amniotic fluid also have associations with structural and chromosomal disorders. Population and race also influence pregnancy outcomes to some extent in certain situations. USG is the most sensitive imaging tool currently available for evaluation of these factors and can offer considerable information in this area. This article aims at reviewing the USG-related developments in this area and the anatomy, physiology, and various pathologies of the placenta, umbilical cord, and the amniotic fluid.

Non-placental causes of intrauterine growth restriction

Placental insufficiency, in some form or fashion, is associated with the majority of cases of intrauterine growth restriction (IUGR). There are numerous causes of IUGR which are not caused primarily by placental insufficiency, but indirectly lead to it. The causes of IUGR can be subdivided into fetal and maternal etiologies. The fetal etiologies consist of genetic diseases, congenital malformations, infections, multiple gestations, and placental/cord abnormalities. The maternal etiologies are categorized as follows: (1) decreased uteroplacental blood flow, (2) reduced blood volume, (3) decreased oxygen carrying capacity, (4) nutrition status, (5) teratogens, and (6) miscellaneous causes such as short interpregnancy intervals, race, maternal age, and low socioeconomic status. Knowledge of the etiologies of fetal growth restriction is essential, so that future care can be targeted at prevention. There are several primary and secondary prevention strategies that can be adopted.

Reference intervals for the cross sectional area of the umbilical cord during gestation

OBJECTIVE

To establish reference values for the sonographic cross-sectional area of the umbilical cord during gestation and to correlate them with fetal anthropometric parameters.

METHODS

A cross-sectional study was performed involving 312 normal pregnant women at gestational ages 24-39 weeks. Measurement of the cross-sectional area of umbilical cord was performed on a plane adjacent to the insertion of the cord into fetal abdomen. The following anthropometric parameters were calculated: biparietal diameter, head circumference, abdominal circumference and femur length. A polynomial regression analysis identified the curves that were better adjusted to the average and standard deviation according to gestational age. Spearman correlation was used to evaluate the correlation of the cross-sectional area of umbilical cord with fetal anthropometric parameters.

RESULTS

A statistically significant correlation was observed between the cord cross-sectional area and gestational age (r=0.376, P<0.001, CI 95%[0.276; 0.467]).

CONCLUSIONS

The reference values of the cross-sectional area of umbilical cord increased according to gestational age until the 33rd week and are related to parameters of fetal growth.

The cross-sectional area of umbilical cord components in normal pregnancy

OBJECTIVE

To determine the normal cross-sectional areas of the umbilical vein, umbilical artery, and Wharton jelly in healthy pregnancies, and correlate the obtained values with fetal anthropometric parameters.

METHODS

A cross-sectional study was performed with 312 women between the 24th and 39th weeks of a normal pregnancy. The cross-sectional areas of umbilical cord vessels were measured at the junction of the cord and fetal abdomen, and the values were subtracted from the total cord cross-sectional area to assess the cross-sectional area of the Wharton jelly. The anthropometric parameters analyzed were biparietal diameter, head circumference, femur length, and estimated fetal weight, and the Spearman correlation was used to assess the correlation between the cross-sectional areas of umbilical cord components and fetal anthropometric parameters. A polynomial regression analysis was performed to identify the curves that best adjusted to mean and standard deviation according to gestational age.

RESULTS

A statistically significant correlation was observed between the cross-sectional areas of cord components and fetal anthropometric parameters (P<0.001) as well as gestational age (P<0.001).

CONCLUSIONS

Reference measurements of the cross-sectional areas of umbilical cord components are important tools in the assessment of fetal growth.

Intrauterine growth restriction and the proliferation of smooth muscle cells in umbilical vessels

AIMS

The purpose of this study was to investigate the proliferation of smooth muscle cells in umbilical vessels of fetuses affected by intrauterine growth restriction (IUGR) and to compare the findings with gestational age-matched control cases.

METHODS

Sixty umbilical cords from fetuses at 36-37 weeks gestation were examined. Fetuses were divided into three groups: group I, appropriate for dates birthweight; group II, IUGR with reassuring fetal status; and group III, IUGR with abnormal umbilical Doppler waveforms. Umbilical cords were immunostained with an antibody to proliferating cell nuclear antigen and Ki-67; stained smooth muscle cells were subsequently counted. Smooth muscle cell density was determined by counting the total number of cells in a representative area of vessel wall and the wall thickness of each vessel was also measured.

RESULTS

Proliferation marker-positive cells were increased in the umbilical vessels of group II compared to group I, and there were more proliferating smooth muscle cells in the umbilical vessels of group III compared to the other two groups. The umbilical vessels of group III showed the highest smooth muscle cell density, but the wall thickness of all vessels was significantly thinner in group III than the other two groups.

CONCLUSIONS

This study showed overproliferation of smooth muscle cells in the umbilical vessel walls associated with IUGR. It is hypothesised that hypoxia might induce this overproliferation given the further proliferation in IUGR fetuses with abnormal umbilical Doppler waveforms. Coexistence of a high cell density and lean vessel walls suggests small smooth muscle cells in umbilical vessels with IUGR.

Sonographic umbilical vessel morphometry and perinatal outcome of fetuses with a lean umbilical cord

PURPOSE

This study was undertaken to assess whether changes in umbilical cord vessel morphometry are associated with an increased risk of adverse perinatal outcome among fetuses with a lean umbilical cord on sonography.

PATIENTS AND METHODS

A total of 160 fetuses with a sonographically lean umbilical cord (cross-sectional area below the 10th percentile for gestational age) after 20 weeks of gestation were enrolled. The cross-sectional areas of the umbilical cord and its vessels were measured. Outcome variables investigated were perinatal death, admission to the neonatal intensive care unit, intrauterine growth restriction, and 5-minute Apgar score.

RESULTS

The proportions of perinatal death (1/96 versus 6/64, p < 0.05) and admission to the neonatal intensive care unit (17/96 versus 22/64, p < 0.05) was significantly higher among fetuses with an umbilical vein area below or equal to the 10th percentile for gestational age than among those with an umbilical vein area greater than the 10th percentile. No differences were found in the proportions of perinatal death, neonatal intensive care unit admission, 5-minute Apgar score < 7, and intrauterine growth restriction when fetuses with umbilical vein areas below or equal to the 10th, the 5th, and the 2.5th percentiles for gestational age were compared. No difference was found in the umbilical artery area and Wharton's jelly area among the groups.

CONCLUSION

Among fetuses with a sonographically lean umbilical cord, a significant relationship exists between an umbilical vein area below or equal to the 10th percentile and an adverse neonatal outcome.

Sonographic umbilical cord morphometry and coiling patterns in twin–twin transfusion syndrome

OBJECTIVE

Monochorionic twins with twin-twin transfusion syndrome (TTTS) provide an ideal model in which to evaluate the influence of differing hemodynamic stress on umbilical cord (UC) morphology. The purpose of this study was to investigate the UC morphometry and UC coiling pattern at ultrasound in monochorionic twin pregnancies with TTTS.

METHODS

A targeted sonographic evaluation of the UC was performed in 21 consecutive twin pregnancies with untreated TTTS. The cross-sectional area of the UC and of its vessels was measured. The Wharton's jelly area was computed by subtracting the vessels area from the area of the UC. The umbilical coiling index (UCI) was calculated as the reciprocal of the sonographic length of one complete vascular coil. The UCs were classified as uncoiled, normally coiled, hypocoiled, hypercoiled and atypically coiled (UCI not valuable).

RESULTS

The UCs of recipient twins were invariably larger than those of donors, and this difference was mainly attributable to both a larger amount of Wharton's jelly and a larger umbilical vein diameter. The proportion of lean UCs was higher in the donor than in the recipient fetuses (18/21 vs 1/21, p < 0.0001), while large UCs were significantly more frequent in the recipient than in the donor twins (13/21 vs 1/21, p = 0.0002). In all twin pairs, a discordant umbilical coiling pattern was observed between the donor and the recipient twin. The prevalence of uncoiled and hypocoiled cords was higher in the donor group, while hypercoiling and atypical coiling were more frequently detected in the recipient group.

CONCLUSIONS

A discordant UC morphometry represents an additional phenotypic feature of twins with TTTS. The discordant intertwin coiling pattern in TTTS argues against an exclusively genetic origin of UC twists, and further supports a key role of hemodynamic forces in coiling development.