Placental End Research Articles

Fetal breathing is associated with increased umbilical blood flow

In humans, fetal breathing movements affect blood velocities in the umbilical vein and artery, but it is not known whether fetal respiratory activity is associated with increased fetal blood flow through the placenta. We therefore tested this hypothesis in the present study. One-hundred and ten women with low-risk singleton pregnancies were each examined three times by ultrasound during the second half of pregnancy. Fetal heart rate, umbilical artery blood velocity, umbilical vein diameter and blood velocity, and umbilical blood flow at the placental end were determined during fetal rest and fetal respiratory movements. Based on 330 observations obtained during fetal rest or breathing activity, no difference was found in the mean fetal heart rate (beats per minute (bpm)) during rest compared with breathing (142 bpm vs. 142 bpm, respectively). Although fetal breathing affected the umbilical artery waveform, there was no difference in the mean time-averaged maximum velocity between rest and breathing: 26.6 (95% CI, 25.1-28.3) cm/s vs. 28.9 (95% CI, 27.2-30.7) cm/s, respectively. The umbilical vein was 27% greater in cross-sectional area and the blood velocity 9% higher during breathing, resulting in a 42% increase in mean umbilical blood flow: 121.8 (95% CI, 109.5-135.0) mL/min at rest vs. 173.0 (95% CI, 158.0-188.6) mL/min during breathing. Venous velocity was calculated from recordings of mean duration 3.7 s at rest and 6.2 s of respiratory activity. Gestational age did not influence the relationship. Fetal breathing is associated with increased umbilical blood flow during the second half of pregnancy. Umbilical vein distension during breathing suggests active endocrine regulation.

Unequal but monozygous: a history of twin-twin transfusion syndrome

Twin-twin transfusion is the major cause of mortality and morbidity in monochorionic twins. Its pathogenesis has been gradually elucidated over the last three centuries. Among obstetricians, there was a long-lasting controversy on the existence of placental anastomoses and whether or not to tie the placental end of the firstborn infant's cord. However, a twin pregnancy practically never could be excluded. Stalpart van der Wiel described a twin-twin vessel connection in 1687. Studies on interfetal anastomoses using injection of placental vessels were published by Smellie in 1752, Osiander in 1781, and Brachet in 1821. Different types of anastomoses, and their associated fetal disorders were classified by Schatz in a series of papers at the end of the 19(th) century. With the advent of ultrasound and laser techniques, prenatal diagnosis and treatment became available in the last decade of the 20(th) century.

Neonatal hypoglycaemia: prevalence and clinical manifestations in Port Harcourt, Nigeria

Background: Neonatal hypoglycaemia is associated with significant long term neuro-developmental sequelae. The signs and symptoms are often non-specific. Some are completely asymptomatic. Many cases therefore remain undiagnosed. This study was therefore designed to determine the prevalence, obstetric and peri-natal factors associated with neonatal hypoglycaemia at the University of Port Harcourt Teaching Hospital, Nigeria. Methods: All neonates delivered between 1st January and 31st May 2006 were recruited. Cord blood specimen was obtained from the placental end of the cord at delivery and assayed for plasma glucose. Relevant obstetric and neonatal data were obtained for each subject. Hypoglycaemia was defined as cord blood glucose level ≤ 2.2 mmol/L. Results: Three hundred and four neonates were recruited. Of this number, 86 were hypoglycaemic giving a prevalence of 28.3%. Out of the 86, 43(50%) were symptomatic while 43(50%) were asymptomatic. The commonest symptoms were respiratory distress (46.5%), cyanosis (20.9%) and lethargy (18.6%). The mean cord plasma glucose for the symptomatic group (1.99+ 0.11 mmol/L) was significantly lower than that of the asymptomatic group (2.07+ 0.06 mmol/L) (p Keywords : Neonatal hypoglycaemia; Clinical manifestations PHMJ Vol. 2 (2) 2008: pp. 166-170

Structural Changes in Umbilical Vessels in Pregnancy Induced Hypertension

Background Pregnancy Induced Hypertension (PIH) is associated with placental morphological changes, alterations in the blood flow patterns in the umbilical vessels and adverse fetal and maternal outcome. Studies have demonstrated changes in the structure of the umbilical vessels but these have not been described across the length of the cord or correlated with the severity of disease. Study design A case control study. Setting Kenyatta National Hospital. Materials and methods Thirty six umbilical cords from newborns of women with and without PIH (18 cases, 18 controls) were obtained and studied with light microscopy. Of the cases 9 women had severe PIH and 9 had mild PIH. Means and standard deviations for the various parameters of the various groups were obtained. Student's t-test and ANOVA were used to compare means, a p value of <0.05 being significant. Results The structure of the umbilical vessels changes from the placental end to the fetal end. The umbilical vein in PIH had a greater wall thickness and a smaller luminal area than in the controls. The vein's wall-luminal ratio increased from the placental to the fetal end. Duplication of the elastic subintimal lamina (ESL) was higher in the cases. The ESL was more commonly duplicated in the fetal end. There were no structural differences between the umbilical arteries in PIH and in the controls. Conclusion PIH is associated with structural changes in the umbilical vessels. These changes are more predominant in the vein than in the artery and in the vein, they are more obvious in the fetal end. The observed increase in wall-luminal ratio from the placental to the fetal end suggests that the fetal end of the umbilical vein has a more refined role in the regulation of blood flow to the fetus.

Umbilical artery pulsatility index: reliability at different sampling sites

To analyse the inter-observer and inter-artery reliability of the umbilical artery (UA) pulsatility index (PI) at different sampling sites. One hundred consecutive singleton pregnancies between 24 and 40 weeks were included. The PI was calculated by two independent operators from both umbilical arteries at the placental end, at a free-floating loop and at the perivesical segment. Reliability analyses were performed between observers and between arteries at each sampling site. The mean percentage of PI difference between arteries was 15.2, 14.5 and 22% at the placental end, free-loop and perivesical site, respectively. The Intraclass correlation coefficients at each site were 0.51, 0.59 and 0.67, respectively. Whereas about 20% of cases showed a percentage of PI difference between arteries greater than 20% at free-loop and placental end sites, and at the perivesical site this figure was 45%. The perivesical sampling site for UA PI calculation is more reliable than at a free-floating loop, albeit without significance, and is significantly more reliable than at the placental end of the umbilical cord. Since discordances in PI between both arteries are more pronounced at the perivesical site, it seems mandatory to evaluate both arteries in this segment.

Biomechanical properties of different segments of human umbilical cord vein and its value for clinical application

No satisfactory effects have been obtained with the use of synthetic blood vessels (diameter <6 mm) as substitutes for human small arteries or veins for the purpose of clinical vascular reconstruction. Therefore, blood vessels of human origin, for example, umbilical cord blood vessels, with their wide availability, still should be considered. However, little information on biomechanical properties of human umbilical cord blood vessels is available. The objective was to provide a theoretical basis for the clinical application of umbilical cord veins as optional material for small-caliber grafts. This was a nonrandomized, noncontrolled in vitro study. The experiment was conducted in the Laboratory of Medical Biomechanics, Yunyang Medical College. Umbilical cord veins of 20 normal fetuses of spontaneous labor were collected by the Department of Obstetrics and Gynecology, Taihe Hospital in Shiyan City, Hubei Province. The fetuses aged 37-40 weeks, and the parturients were 20-30 years old. Umbilical cord veins of the 20 fetuses were used and the placental ends were treated as proximal ends while the fetal ends as distal ends. The fetal ends were divided into three segments: proximal, middle, and distal segments. The relationship between pressure of umbilical cord veins segments and the diameters was measured on the biomechanical experiment stand for soft tissues, and then the elastic modulus was calculated. The materials were transversely extracted, refrigerated, and sliced up before HE staining. The geometrical morphology indexes were measured by a computer image analysis system (Leica-Q500IW). The main outcome measures were: incremental elastic modulus (E(inc)), pressure-strain elastic modulus (E(p)), volume elastic modulus (E(v)), diameter, and wall thickness of the veins. E(inc), E(p), and E(v) of umbilical cord veins of proximal, middle, and distal segments increased with the pressure elevated. The three kinds of elastic modulus of proximal segments (E(inc): 26.98 +/- 3.21, E(p): 16.58 +/- 2.12, E(v): 8.31 +/- 2.35) were all lower than those of distal segments (E(inc): 33.20 +/- 4.21, E(p): 119.45 +/- 2.87, E(v): 9.71 +/- 1.32) (F = 95.74-126.52, p < 0.05), and a tendency to increase was shown from proximal segments to distal segments. Media thickness [(0.30 +/- 0.05)] mm, (0.24 +/- 0.03) mm] and the diameters [(3.07 +/- 0.12) mm, (2.30 +/- 0.13) mm] decreased gradually from proximal to distal segments (F = 12.76, p < 0.01). It is feasible to use umbilical cord veins as substitutes for the transplantation of small-caliber arteries in terms of basic biomechanical properties. On vascular grafting, different segments of umbilical cord veins should be chosen cautiously so that the biomechanical characteristics of umbilical cord vein grafts could be in accordance with those of host to increase the long-term patency rate of transplanted blood vessels.

Reference ranges for serial measurements of blood velocity and pulsatility index at the intra‐abdominal portion, and fetal and placental ends of the umbilical artery

To construct reference ranges for serial measurements of umbilical artery (UA) blood flow velocity and pulsatility index (PI) at standardized insonation sites during the second half of pregnancy. This was a prospective longitudinal study of the umbilical circulation. UA blood flow velocities were measured at the intra-abdominal portion, fetal end and placental end at 4-weekly intervals at 19-42 weeks of gestation in 130 low-risk singleton pregnancies. A total of 513 observations were used to construct the reference ranges using regression statistics and multilevel modeling. UA blood velocities and PI were higher at the intra-abdominal portion and fetal end than at the placental end. The gestational age-related increase of end-diastolic velocity was greater than the corresponding increase of the peak systolic velocity at all locations. The mean differences (delta values) of UA blood velocities between the fetal and placental ends increased and that of PI decreased with advancing gestational age. UA Doppler parameters vary significantly at different locations. We have established new reference ranges for the UA velocities and PI at standardized locations based on longitudinal observations, which should be useful for the surveillance of fetuses with repeated observations.

Regional difference of endothelium-dependent contractility in human umbilical artery

To investigate whether vascular reactivity of the umbilical artery influences differences in Doppler waveform depending on the sampling site along the cord, we studied a regional difference of endothelium-dependent vascular contractility in human umbilical artery using mechanical responses to the quick stretch of vascular smooth muscle strips. The umbilical artery resistance index (RI) values for the fetal end were significantly higher than those for the placental end. In endothelium-intact strips, stretch-induced contraction of the umbilical artery appears to decrease from the fetal to the placental end of the umbilical artery. No significant differences were noted between strips from the two locations when endothelial cells were rubbed, indicating that this regional difference is related to endothelial cell function. Indo-methacin decreased the stretch-induced contraction of endothelium-intact strips, but tetrodotoxin did not affect this association, suggesting that arachidonic acid metabolism via the cyclooxygenase pathway contributes to modulation of human umbilical artery responsiveness to stretch. These findings suggest that the difference in Doppler waveform of the umbilical artery depending on the sampling site is related to differences in vascular resistance that result from endothelium-related function.

Oxidant-Antioxidant System Changes Relative to Placental-Umbilical Pathology in Patients with Preeclampsia

Objective. It is speculated that lipid peroxidation is responsible for the pathologic changes that occur in the uteroplacental vasculature of women with preeclampsia. The aim was to investigate this proposed relationship. Materials and Methods. The prospective study involved 90 pregnant women. Thirty had mild preeclampsia, 30 had severe preeclampsia, and 30 were healthy pregnant women (controls). The data collected for each case were umbilical cord and placental pathologies, plasma malondialdehyde (MDA) level, and levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activity in erythrocytes. Group findings were compared. Results. The mean MDA level in the severe preeclampsia group was higher than the corresponding findings in the mild preeclampsia and control groups (p < 0.001 for both). Also, the MDA level in the mild preeclampsia group was significantly higher than was the control level (p < 0.001). The mean SOD activity level in the severe preeclampsia group was lower than the corresponding results in the mild preeclampsia and control groups (p < 0.001 for both). The mean GSH-Px levels in the mild and severe preeclampsia groups were both significantly lower than was the corresponding finding in the control group (p < 0.01). Compared to the control group, both preeclampsia groups had significantly higher frequencies for placental infarction, villous fibrosis, increased numbers of syncytial nodes, and thickening of vessel walls and lumen obliteration (p < 0.001 for all). Villous fibrinoid necrosis, perivillous fibrosis, and increased villous vascularization were also significantly more frequent in both preeclampsia groups than in the control group, but the differences for these parameters were smaller (p < 0.01 for all). Examination of the samples from the placental ends of the umbilical cords revealed significantly higher frequencies of endothelial irregularity, endothelial shedding, and basal membrane thickening in both preeclampsia groups than in those of the control group (p < 0.001). The same findings were noted in the middle sections of the cords (p < 0.001). At the fetal ends of the umbilical cords, both preeclampsia groups had higher frequencies of endothelial irregularity than did the control group (p < 0.001); however, the frequencies of the more severe pathologic findings (endothelial shedding, basal membrane thickening) in the three groups were similar. Conclusion. The frequencies of pathologic changes in the placenta and umbilical vessels of women with preeclampsia parallel the severity of this condition. These changes also parallel plasma levels of MDA, the end product of lipid peroxidation.

Single and Multiple Umbilical Cord Cysts in Early Gestation Two Different Entities

Umbilical cord cysts are reported in up to 3% of births. Their presence in mid- and late pregnancy is strongly associated with chromosomal disorders and structural defects, but the significance of cysts detected in earlygestation remains unclear. This targeted sonographic study included 1159 consecutive women with singleton pregnancies who had ultrasound studies between 7 and 14 weeks gestation. The morphology and morphometry of the umbilical cod were examined by transvaginal sonography using an 8-MHz probe and color Doppler recording. An umbilical cord cyst was diagnosed when a thin-walled cystic structure within the cord could be clearly distinguished from the yolk sac. Women first examined at 7-10 weeks gestation had another scan at 11-14 weeks. Umbilical cord cysts were found in 24 cases, 2.1% of the study population. Six women had multiple cysts. Maternal age and parity were comparable in women with and those without umbilical cord cysts. Single cysts were fairly evenly distributed at the fetal or placental end of the cord or in its middle. Five of the 24 women miscarried. All women having a single cord cyst delivered an apparently normal infant without signs of chromosomal abnormality. One of these women, with premature rupture of membranes, miscarried. Four women with multiple cord cysts had a miscarriage by 14 weeks gestation. Trisomy 18 was discovered in 2 of 3 cases having karyotyping. One woman with multiple umbilical cord cysts had a fetus with obstructive uropathy. The remaining woman delivered a healthy infant at term. Miscarriage was significantly more frequent in women with multiple cord cysts. Single cysts were no longer evident at 11-14 weeks in all women whose infants survived. Macroscopic evidence of an umbilical cord cyst was not present at the time of delivery in any case. A favorable outcome might be expected when a single umbilical cord cyst is discovered sonographically in early pregnancy. Multiple cysts, however, carry an increased risk of adverse pregnancy outcomes.

Angioma racemosum der Nabelschnur - Pränatale Diagnose eines Falles mit erfolgreichem Schwangerschaftsausgang

Wir berichten über den seltenen Fall eines racemösen Angioms der Nabelschnur, welches in der 28. Schwangerschaftswoche mittels Ultraschall diagnostiziert wurde. Der Tumor befand sich am plazentaren Ende der Nabelschnur und bestand aus einem angiomatösen Knoten mit shuntenden Gefäßen unterschiedlicher Größe und Form. Der Fetus zeigte keine strukturellen Auffälligkeiten und wurde nach Diagnosestellung engmaschig mittels Doppler-Sonographie überwacht. Die Nabelschnurgefäße zeigten normale Flussparameter während der gesamten Schwangerschaft, aufgrund einer zunehmenden intrauterinen Wachstumsretardierung wurde die Schwangerschaft in der 39. Schwangerschaftswoche mittels primärer Sectio caesarea beendet. Die Neugeborenenperiode verlief komplikationslos und der inzwischen 1,5 Jahre alte Knabe entwickelt sich normal.

Doppler velocimetric indices from the abdominal and placental ends of the umbilical artery of growth‐restricted fetuses

Doppler velocimetric indices from the abdominal and placental ends of the umbilical artery of growth‐restricted fetuses

Loss of dopamine D1‐like receptors in the umbilical artery of pre‐eclamptic subjects

1. The influence of pre-eclampsia on the density and pattern of dopamine D1-like receptors was studied in frozen samples of the placental end of the umbilical artery by using radioligand binding and autoradiographic techniques in combination. 2. Analysis was performed on normotensive (n = 10) and pre-eclamptic subjects (n = 9) undergoing caesarean delivery, using [3H]-SCH 23390 as a ligand. Pre-eclamptic patients received a low salt diet and were treated with magnesium sulphate and hydralazine. The possibility that this treatment may cause changes in the density of dopamine D1-like receptors was evaluated by treating male Wistar rats in the same way and by determining [3H]-SCH 23390 binding in sections of the kidney which represents an organ containing dopamine D1-like receptors. 3. The density of dopamine D1-like receptors of the umbilical artery, which are probably vasodilatory, was decreased in pre-eclamptic compared with normotensive subjects. In contrast, the affinity of the radioligand for dopamine D1-like receptors was not statistically different between normotensive and pre-eclamptic subjects. Low salt diet, magnesium sulphate and hydralazine treatment did not affect [3H]-SCH 23390 binding to sections of rat kidney. This suggests that changes in the density of dopamine D1-like receptors in pre-eclamptic patients are a specific phenomenon not dependent upon antihypertensive measures. 4. Analysis of the pharmacological profile of [3H]-SCH 23390 binding to sections of the umbilical artery both in normotensive and pre-eclamptic subjects indicates the labelling of dopamine D5 receptors. 5. These findings collectively suggest that the dopaminergic vasodilatory tone in the umbilical artery is impaired in pre-eclampsia. The possible significance of these data should be clarified in future studies.

Reference Values for Doppler Velocimetric Indices from the Fetal and Placental Ends of the Umbilical Artery During Normal Pregnancy

Reference Values for Doppler Velocimetric Indices from the Fetal and Placental Ends of the Umbilical Artery During Normal Pregnancy

Reference values for Doppler velocimetric indices from the fetal and placental ends of the umbilical artery during normal pregnancy.

A range-gated Doppler ultrasound system combined with a real-time imaging system was used to determine arterial blood velocity values from the fetal and placental ends of the umbilical cord in 269 normal pregnancies between 17 and 40 weeks, menstrual age. The systolic-diastolic ratio (S/D), pulsatility index (PI), and resistance index (RI) were higher at the fetal end compared to the placental end of the cord. The individual differences in these Doppler indices, obtained between the fetal and placental recording sites, were inversely related to menstrual age: S/D: r = -0.38, p < 0.001; PI: r = -0.25, p < 0.001; and RI: r = -0.15, p < 0.01. After normalization for the angle of insonation, the peak systolic velocity was higher and the end-diastolic velocity was lower at the fetal than at the placental end of the cord. It is concluded that routine recordings for Doppler velocimetric indices should take into account the recording site on the umbilical cord in order to reduce methodological sources of variance, especially during midgestation. Furthermore, the data presented here in the form of the median and percentile values are proposed as normal reference values to facilitate this procedure.

Umbilical blood flow relations in patients with gestosis-- gestosis-specific Doppler phenomenon

A collective of 48 pregnant women, whose pregnancies showed signs of a pregnancy-induced hypertension or gestotic tendencies was examined by Doppler ultrasound. The subject of interest was the resistance along the umbilical cord. Measurements were taken both ends of the umbilical cords. Usually, a decline of the indices is seen, which makes the difference between the two ends (Delta F) turn out positive. Pregnancies with any sign of a gestotic development, showed elevated resistances at the placental end of the cord. The indices of the foetal abdominal insertion were just about the same. Delta F changed significantly in our group of patients. Here, the values of both sides either did not differ from one another or the placental indices even exceeded the foetal ones. We called this special constellation of umbilical indices a Doppler phenomenon characterising gestotic pregnancies.

ADAM sequence and innocent amniotic band: Manifestations of early amnion rupture

Thirteen placentas with early amnion rupture (EAR) are described. These placentas were characterized by the absence of amniotic epithelium on the fetal surface, presence of a slightly fibrotic small amniotic band (remnant) attaching to the umbilical cord at the placental end, and the presence of degenerated vernix squamous cells in the fibrous stroma of chorion and amnion. Eight fetuses had ADAM sequence. Six of these fetuses were miscarried between 16 and 28 weeks of gestation. Two affected infants were born alive at gestational ages of 29 and 39 weeks. Five infants were spared by ADAM sequence; two had the umbilical cord strangulated by an amniotic band and were delivered at 27 and 37 weeks. In the 3 infants unassociated with ADAM sequence or strangulation of the umbilical cord, their placentas were interpreted as having innocent amniotic band (IAB) and they were delivered between 32 and 40 weeks. The findings in this study support Torpin's hypothesis that ADAM sequence is a complication of EAR. This ADAM sequence due to simple EAR must be separated from the limb body wall malformation complex because visceral anomalies are uncommon in the former condition but are frequently seen in the latter. In this study the placental pathology of EAR was helpful in confirming the ADAM sequence in the fetus.

Embryonic remnants of the umbilical cord: Morphologic and clinical aspects

Embryonic vestiges of the umbilical cord are classic findings in routine morphologic examination of the placenta. In order to evaluate their clinicopathologic significance, we examined samples from the fetal and placental ends of 1,000 umbilical cords and collected the principal clinical findings of the corresponding newborns. Microscopic evidence of embryonic remnants were found in 231 cases (23.1%) divided into remnants of the allantoic duct (63%), the omphalomesenteric duct (6.6%), and the embryonic vessels (30.4%), including one case of hemangioma and an accessory small artery. There were no significant clinical differences between the three vestigial groups, and no particular association with congenital malformations or perinatal complications. In 70.9% of the cases, the embryonic remnants were found at the fetal end of the umbilical cord, where most tumors of the cord develop.

DEFECTIVE REDUCING ACTIVITY OF NEWBORN PLATELETS

Activation of platelet(Plt)plasma membrane is associated to Cytochrome C(Cyt.C)reducing activity.We studied this activity in newborn Plts stimulated by low or high molar ADP, collagen,thrombin and opsonized-zymosan(opZ).Cord blood was collected from placental end of the cut umbelical cord.The platelet-rich plasmas(PRPs)were layered on Ficoll 23%(w/v) to eliminate leukocyte contamination.Zymosan was opsonized with adult citrated-plasma(AB Rh-).Cyt.C reduction was determined spectrophotometrically,and aggregation(in PRPs or Plt suspensions)by the change in light transmission.The Cyt C reduction was undetectable(n=20)in newborn Plts stimulated with all stimuli(adult controls:10-20 nmol/109 Plts/10 min)including collagen(4 μg/ml)and thrombin(1.67 U/ml)able to induce their aggregation.Newborn Plts did not aggregate after low molar concentrations of agonists(Hathaway,1970)or after immunologic stimulation(Del Principe,ESPHI 1985).opZ plus subthreshold ADP elicited a 90% aggregation, but not Cyt.C reduction.The defective membrane redox reactions reflect an alteration in the process leading to membrane activation,and possibly account for the impaired functional response of newborn platelets.

The water content of the human umbilical cord.

105 umbilical cords from 53 term and 52 preterm newborn infants were freeze-dried after removal of the blood vessels, to determine the water content. The mean umbilical cord water content (i.e. mean of water content of fetal and placental ends of the cord), was 88.9% (SD 2.73) for term cords and 91.9% (SD 1.99) for preterm cords. The mean water content fell with increasing gestation. The fetal end of the cord had a significantly higher water content than the placental end. Similarly, the volume of a 4-cm length segment of cord was significantly greater at the fetal than placental end. There was no correlation between cord water content or volume and several other variables including birthweight, size for gestational age and placental weight. These observations suggest a metabolically active role for the umbilical cord.