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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.

Objectives: The objectives of this study were to establish gestational age-specific reference ranges for cross-sectional area of the umbilical cord, and its components, in twin pregnancies and to compare them with previously reported singleton reference ranges., Methods: This was a prospective longitudinal study involving uncomplicated dichorionic twin pregnancies. Sonographic measurements of the cross-sectional area of the umbilical cord, umbilical vein and arteries and Wharton's jelly were obtained in a plane adjacent to the fetal abdomen, every 3 weeks, between 18 and 32 weeks of gestations. Multilevel regression analysis was used to determine gestational age-specific reference ranges for each parameter, and these were plotted against singleton pregnancy references., Results: Three hundred and thirty four ultrasound scans were performed in 44 twin pregnancies, between 18 and 32.9 weeks (mean: 3.8 ± 0.7 scans/pregnancy and mean interval between scans: 3.3 ± 0.9 weeks). All umbilical cord cross-sectional areas (total, vein, artery and Wharton's jelly) showed a significant increase with gestational age. Compared with singleton pregnancy ranges, mean values were considerably lower in twin pregnancies and resemble the lower limits observed in singletons., Conclusion: In twin pregnancies, cross-sectional area of the umbilical cord, and its components, increases between 18 and 32 weeks, and mean values are substantially lower compared with singleton pregnancies., (© 2015 John Wiley & Sons, Ltd.)

Objective: To investigate the reconstruction of digital three-dimensional (3D) model of normal human placental vascular network based on MRI data in vitro., Methods: Six full term placentas were collected, casted with modified self-curing denture base resin and scanned by T1 e-THRIVE high resolution magnetic resonance imaging. MRI images were imported into Mimics 14.0 software for 3D reconstruction, and the 3D model was compared with placental vascular casting model., Results: (1) The placental vascular network could be obtained on MR 2D images. The 3D model were reconstructed successfully, which showed clear, realistic images. The 3D model could be zoomed and revolved from any direction to observe the branches of arteries and veins. (2) The umbilical vein and 2 umbilical arteries could be seen in the 3D model. In the root of the umbilical cord, the umbilical vein divided into 5-7 branches. While the 2 umbilical arteries anatomoses to form blood sinus and then devided into sub-branches. All the peripheral vessels ended in chorionic plate with abundant sub-branches. (3) When compared with the casting of placental arterial-venous vascular network, the morphology, structure, angle and trend of vessels in 3D model was consistent with the casting network., Conclusions: Reconstruction of digital 3D model of normal human placental vascular network based on MRI in vitro is a new and promising method for the study of placental vasculature. It has better vascular exposure, free rotation, radiation-free. It provides a promising base for the study of placental vasculature in vivo in the future.

The most significant anatomical structure of the umbilical cord is its level of coiling. The coiled geometry of the umbilical cord largely affects umbilical blood flow that is vital for fetus's well-being and normal development. In this study, we developed a computational model of steady blood flow through the coiled structure of an umbilical artery. The results showed that the driving pressure for a given blood flow rate is increasing as the number of coils in cord structure increases. The driving gradient pressures also vary with the pitch that dictates the coils' spreading. The coiled structure is resulting in interwoven streamlines along the helix and wall shear stresses (WSS) with significant spatial gradients along the cross-sectional perimeter anywhere within the helical coil. These gradients may have an adverse effect on the development of the fetus cardiovascular system in cases with over coiling (OC) or under coiling (UC) characteristics. The number of coils does not affect the distribution and levels of WSS. However, when the coils are more spread (eg, larger pitch number), the maximal WSS is significantly smaller. Cases with twisted and OC cords seem to yield very large values and gradients of WSS, which may place the fetus into high risk of abnormal development.

Approximately 40 years ago, Dr. Peter Dunn introduced a simple method to determine the insertion length of umbilical catheters in neonates, by using the 'shoulder-umbilical' (S-U) length. Since then, various studies have reported a high rate of malposition of umbilical catheters. One of the possible reasons is that the method used to determine the S-U length varies among paediatric professionals. We performed a questionnaire study among 101 paediatric professionals in the Netherlands and found that the method used by the participants to measure the S-U length was highly inconsistent. Placement of an umbilical venous catheter in a too deep position may lead to potentially life-threatening complications. Therefore, uniformity in measurement is paramount for clinical and teaching purposes. Paediatric professionals using Dunn's definition to place umbilical catheters should adhere more strictly to the original description of the measurement of the S-U length., ((c) 2008 S. Karger AG, Basel.)

Ultrasonographic prenatal diagnosis of single umbilical artery (UA) is well documented, but the exact siding of the single UA and its correlation with the occurrence of other congenital malformations and the outcome of the baby remain unclear. We report our experience with 46 cases of prenatally diagnosed single UA. This is the first prospective study of a large number of consecutive pregnancies in which the side of the existing artery was identified in fetuses with a single UA. Most of the cases were identified by transvaginal sonography at 14-16 weeks' gestation. A right artery was detected in 25 fetuses (54.3 per cent), and a left artery in 21 cases (45.7 per cent). Six fetuses (13 per cent) had associated anomalies, five of them in the urinary system. No correlation was found between the type or severity of the malformations and the side of the missing (or existing) UA. In our experience, the exact location of the single UA can be reliably determined by ultrasonography from the beginning of the second trimester of pregnancy. The selection process of the missing (or existing) vessel is likely to be random, even though a right single artery was seen slightly more often.

We investigated whether variations in mode of attachment of umbilical cords and vessels coincided with differences in maternal haemoglobin genotype and neonatal factors or placental micro-volumetric composition. The incidence of placentae with marginally inserted cords, or those in which umbilical vessels separated prior to insertion, was not statistically different in samples from sickle cell patients having haemoglobin-SS and haemoglobin-SC genotypes, as compared with haemoglobin-AA controls. Results obtained from analysis of variance (ANOVA) suggest that the mode of insertion (status) of umbilical vessels may have clinical significance, because it produced differences in the main effects associated with neonatal gestational age, placental weight, and placental index. Point counting stereology was employed to estimate the microscopic compartment volumes of placentae prior to an assessment of statistical association between the data obtained and the status of umbilical vessels and maternal haemoglobin genotype. Furcate placentae (with separated umbilical vessels) had statistically greater than normal volumes of villi, villous trophoblast, and syncytial knots. We deduce that furcate placentae are prone to early delivery, because they are heavier, having more voluminous villi with more trophoblast and syncytial knots than controls.

The Poiseuille equation of fluid flow suggests that umbilical cord length and cord blood viscosity may affect resistance to flow and thus affect the systolic/diastolic ratio. In this prospective study of 40 uncomplicated term pregnancies, we sought to define the relationship of umbilical cord length and cord blood hematocrit level (as an index of viscosity) to the umbilical artery systolic/diastolic ratio. To focus on these factors, we minimized known sources of systolic/diastolic ratio variability and controlled for fetal heart rate. Linear regression revealed that fetal heart rate contributed 18% of the systolic/diastolic ratio variability. Conversely, umbilical cord length and cord blood hematocrit level were not related to umbilical artery systolic/diastolic ratio. We conclude that normal variations in cord blood hematocrit level and umbilical cord length do not significantly affect systolic/diastolic ratio.