Comparative analysis of placental vasculature and placental volume in normal and IUGR pregnancies with the use of three-dimensional Power Doppler

Ultrasound Microvessel Imaging of the Human Placenta Demonstrates Altered Vessel Densities in Fetal Growth Restriction With Vascular and Immune Pathologies: A Pilot Case-Control Study

OBJECTIVES

Fetal growth restriction (FGR) is commonly associated with placental dysfunction, increasing perinatal morbidity and mortality. Visualizing placental vessels in utero would be advantageous for identifying functional FGR cause and determining proper management strategies. We aimed to utilize high-sensitivity ultrasound microvessel imaging (HUMI) for quantifying placental vessel density (VD) in pregnancies diagnosed with FGR.

METHODS

This pilot case-control study enrolled subjects in the third trimester with a diagnosis of FGR (n = 40) and gestational age-matched controls with normal fetal growth (n = 20) at a 2:1 ratio, respectively. The Verasonics Vantage ultrasound system was used to perform HUMI on each participant at one timepoint. Scanning involved randomized singular value decomposition-based clutter filtering to identify the villous tree, followed by step-by-step scanning to acquire 3-dimensional-like data. Mean VD was calculated from three ultrasound measurements per subject. Additional clinical and pathology data were also collected and compared.

RESULTS

Sixteen participants were utilized to establish the scanning protocol and 2 met exclusion criteria at delivery. Thus, VD was successfully measured on 42 pregnancies scanned at 35 weeks 5 days on average. In FGR (n = 24), placental VD was significantly reduced compared to controls (P < .01). VD measures were as good at predicting FGR as systolic/diastolic (S/D) ratios (area under the curve 0.86 versus 0.80). In a smaller cohort, VD in placentas with a diagnosis of inflammatory villitis (n = 10) by histology showed an increase in VD compared to those without inflammation (P = .01). Low VD was correlated with increased S/D ratios (P = .03).

CONCLUSIONS

HUMI is useful for identifying altered placental vascularization in utero for FGR. VD may be a valuable indicator for placental health and could lead to improved risk stratification methods considering underlying biology.

Placenta: an old organ with new functions

The transition from oviparity to viviparity and the establishment of feto-maternal communications introduced the placenta as the major anatomical site to provide nutrients, gases, and hormones to the developing fetus. The placenta has endocrine functions, orchestrates maternal adaptations to pregnancy at different periods of pregnancy, and acts as a selective barrier to minimize exposure of developing fetus to xenobiotics, pathogens, and parasites. Despite the fact that this ancient organ is central for establishment of a normal pregnancy in eutherians, the placenta remains one of the least studied organs. The first step of pregnancy, embryo implantation, is finely regulated by the trophoectoderm, the precursor of all trophoblast cells. There is a bidirectional communication between placenta and endometrium leading to decidualization, a critical step for maintenance of pregnancy. There are three-direction interactions between the placenta, maternal immune cells, and the endometrium for adaptation of endometrial immune system to the allogeneic fetus. While 65% of all systemically expressed human proteins have been found in the placenta tissues, it expresses numerous placenta-specific proteins, whose expression are dramatically changed in gestational diseases and could serve as biomarkers for early detection of gestational diseases. Surprisingly, placentation and carcinogenesis exhibit numerous shared features in metabolism and cell behavior, proteins and molecular signatures, signaling pathways, and tissue microenvironment, which proposes the concept of "cancer as ectopic trophoblastic cells". By extensive researches in this novel field, a handful of cancer biomarkers has been discovered. This review paper, which has been inspired in part by our extensive experiences during the past couple of years, highlights new aspects of placental functions with emphasis on its immunomodulatory role in establishment of a successful pregnancy and on a potential link between placentation and carcinogenesis.

Role of Placental Vascularization Indices and Shear Wave Elastography in Fetal Growth Restriction

OBJECTIVE

To evaluate the role of placental vascularisation indices using 3D-Power Doppler and placental elasticity using Shear Wave Elastography (SWE) in Fetal Growth Restricted (FGR) pregnancies and to assess their correlation with perinatal outcomes.

METHODS

This prospective case-control study was conducted from June 2018-2020. Thirty women with FGR and thirty controls (24-36 weeks) underwent grayscale and Doppler ultrasonography followed by measurement of vascularisation indices and SWE from the central and peripheral parts of fetal and maternal surfaces of the placenta. Participants were followed till delivery and perinatal outcomes were noted.

RESULTS

Vascularisation indices were significantly reduced among FGR vs. controls: Vascularisation Index (VI): 20.90 ± 5.46 vs. 31.49 ± 3.89, Flow Index (FI): 26.29 ± 1.70 vs. 30.85 ± 2.02, Vascularisation- Flow Index (VFI): 7.06 ± 2.42 vs. 12.37 ± 2.43, p < 0.001. The mean placental SWE (17.36 ± 1.50 kPa) in FGR pregnancies was significantly higher as compared to controls (4.14 ± 1.14 kPa), p < 0.001. Neonatal polycythaemia and hyperbilirubinemia were significantly increased in FGR pregnancies with higher SWE value. Receiver operating characteristic curve-based cut-off of VI for intensive care requirement was 23.0 (sensitivity: 75%, specificity: 71%) and for tachypnea was 22.8 (73% sensitivity and specificity). The cut-off of FI for low birth weight was 25.7 (sensitivity: 69.6%, specificity: 71.4%).

CONCLUSION

This study demonstrates that increased placental stiffness and reduced vascularisation in FGR indicate possible placental pathology. Both modalities help in predicting perinatal complications. Hence, vascularisation indices and SWE reflect the extent of placental insufficiency and can be useful adjuncts in diagnosis.

Relationship of Placental Vascular Indices with Macroscopic, Histopathologic, and Intraoperative Blood Loss in Placenta Accreta Spectrum Disorders

Introduction. Placenta accreta spectrum is an obstetrical complication with a high level of morbidity. The 3-dimensional (3D) power Doppler method has been widely used to improve the diagnosis. Therefore, this study aims to elucidate better the relationship of quantitative placental vascular indices towards macroscopic findings, histopathological grading, and intraoperative blood loss in the disorder. Methods. A preliminary study using a cross-sectional design was conducted on 34 clinically diagnosed women with PAS. The 3D power Doppler with the VOCAL II software was used to measure the level of vascularization index (VI), flow index (FI), and vascularization flow index (VFI). Gross anatomical appearance and histopathology results were categorized as accreta, increta, and percreta. In addition, the intraoperative blood loss level was measured, and 1500 mL was the cutoff for massive hemorrhage. Results. The vascularity indexes were VI = 44.2 (23.7–74.9), FI = 35.4 (24.9–57), and VFI = 15.3 (8.5–41.7). The FI value was significant in comparing gross pathological stages ( $p=0.015$ ) and had a moderate positive correlation in relation to blood loss (r = 0.449). VI, FI, and VFI above the cutoff values were shown to be strongly associated with blood loss $\ge$ 1500 cc with aOR 7.00 (95% CI 1.23–39.56), aOR 10.00 (95% CI 1.58–63.09), and aOR 9.16 (95% CI 1.53–54.59), respectively. Conclusion. This preliminary study demonstrated an initial potential of the FI value from 3D USG power Doppler to predict the depth of PAS invasion before surgery and intraoperative blood loss level.

New insights into human functional ultrasound imaging

Ultrasound imaging is a vital tool for exploring in vivo the placental function which is essential to understand pathological phenomena such as preeclampsia or intrauterine growth restriction. As technology advances including ready availability of three-dimensional (3D) probes and novel software, new markers of placental function become possible. The objective of this review was to provide an overview of the new ultrasound markers of placental function with a focus on the potential clinical application of three-dimensional power Doppler (3DPD). A broad-free text literature search was undertaken based on human placental studies and sixty full-text studies were included in this review. Three-dimensional power Doppler is a promising technique to predict preeclampsia in the first trimester. However, the influence of external factors such as body mass index, parameter standardisation and machine settings still need to be addressed. Contrast-enhanced ultrasound is currently reserved for research, because the required injected contrast mediums are not currently approved for use in pregnancy, although the safety data is reassuring.

First trimester screening for pre-eclampsia and intrauterine growth restriction using three-dimensional Doppler angiography (SPIRIT): protocol for a multicentre prospective study in nulliparous pregnant women

INTRODUCTION

Pre-eclampsia (PE) and intrauterine growth restriction (IUGR) are two major pregnancy complications, related to chronic uteroplacental hypoperfusion. Nowadays, there is no screening or diagnostic test for uteroplacental vascularisation deficiency in pregnant women. Since 2004, 3 three-imensional power Doppler (3DPD) angiography has been used for the evaluation of uteroplacental vascularisation and three vascular indices are usually calculated: Vascularisation Index (VI), Flow Index (FI) and vascularisation-FI (VFI). A high intraobserver and interobserver reproducibility and a potential interest for placental function study were reported by our team and others.The main objective of our study is to determine differences in 3DPD indices at first trimester between pregnancies defined at their outcome as uncomplicated pregnancy, PE (mild and severe) and IUGR in nulliparous women.

METHODS AND ANALYSIS

This is a national multicentre prospective cohort study conducted in four French maternity units. We expect to include 2200 women in a period of 36 months. The nulliparous pregnant women will be recruited during their first trimester consultation (11-13+6 gestation week (GW)).The 3DPD and uterine artery Doppler acquisition will be included in the current routine 11-13+6 GW ultrasound. Also, additional blood samples will be taken for biomarker analysis (PAPP-A and P1GF) and biological collection. Uteroplacental VIs (FI and VFI) will be measured. For each subgroup (uncomplicated pregnancy, PE and IUGR), mean values in 3DPD indices will be computed and compared using a pairwise t test with a Bonferroni correction p value adjustment.

ETHICS AND DISSEMINATION

The study was approved by the French Ethics Committee, the Comité de Protection des Personnes SUD MEDITERRANEE IV on 13 February 2018 with reference number 17 12 03. The results of this study will be published in a peer-reviewed journal and will be presented at relevant conferences.

TRIAL REGISTRATION NUMBER

NCT03342014; Pre-results. PHRCN-16-0567.

First trimester placental volume and vascular indices in pregestational diabetic compared to nondiabetic pregnant women

AIM

Comparing placental volume (PV) and vascular indices in pregestational diabetic and nondiabetic pregnant women at 11 and 13 weeks gestation.

METHODS

A case-control study conducted at Ain Shams University Maternity Hospital in collaboration with Feto-maternal Unit for Ultrasound Assessment, Ain Shams University Maternity Hospital, Egypt. Ninety-two pregnant women divided into two groups: Group A included 46 women with pregestational diabetes mellitus and group B included 46 nondiabetic pregnant women as control. All participants had PV, vascularization index (VI), flow index (FI) and vascularization flow index (VFI) calculated using three-dimensional (3D) ultrasonography and 3D power Doppler at 11 and 13 weeks of pregnancy.

RESULTS

At 11 weeks, the mean VI, FI and VFI in diabetic group (17.70 ± 12.62, 40.72 ± 11.03 and 7.77 ± 6.37, respectively) were insignificantly higher than in nondiabetic group (12.14 ± 12.62, 34.59 ± 9.66 and 6.52 ± 14.20, respectively) while mean PV in diabetic group (26.90 ± 14.74) was insignificantly lower than in nondiabetic group (27.53 ± 17.46). Also at 13 weeks, the results were not different as the mean VI, FI and VFI in diabetic group (16.51 ± 9.81, 42.52 ± 7.47 and 8.12 ± 7.55, respectively) were insignificantly higher than in nondiabetic group (16.37 ± 14.17, 40.29 ± 17.52 and 7.08 ± 4.35, respectively), and mean PV in diabetic group (52.04 ± 17.95) was insignificantly lower than in nondiabetic group (54.46 ± 17.85). There was strong positive correlation between HbA1C level and VFI measured at 13 weeks gestation.

CONCLUSIONS

Placental indices in early pregnancy do not seem to be useful markers to anticipate placental pathology in pregestational diabetes, however there might be a role for HbA1C level measurement to anticipate such complications.

Uterine and placental blood flow indexes and antinuclear autoantibodies in unexplained recurrent pregnancy loss: should they be investigated in pregnancy as correlated potential factors? A retrospective study

BACKGROUND

The potential role of antinuclear antibodies (ANA) in recurrent pregnancy loss (RPL) pathogenesis is still debated, although some evidences suggest that they could affect pregnancy outcome, leading to a higher miscarriage rate in these patients. A hypothesized mechanism is through changes in uterine flow in pre-conceptional stage, by modifying endometrial receptivity in RPL. However, scant data are available, in pregnancy, about their role in RPL placental perfusion, also in relation to its potential treatments, such as low molecular weight heparin (LMWH). The aim of this study is to retrospectively further investigate the correlation between two-dimensional (2D) and three-dimensional (3D) uterine and placental flow indexes and the presence or the absence of ANA in women with unexplained RPL (uRPL), treated or not treated with LMWH.

METHODS

2D Doppler measurement of pulsatility index (PI) of the uterine arteries and 3D ultrasonography determination of vascularization index (VI), flow index (FI) and vascularization flow index (VFI) was carried out with the aid of the virtual organ computer-aided analysis (VOCAL) technique in LMWH treated (n 24) and not treated-uRPL patients (n 20) and in the relative control group (n 27), each group divided in ANA+ and ANA- subgroups. Serum assay for the presence of ANA was performed in all women.

RESULTS

No differences were found in PI, VFI and VI values, by comparing the different groups. A difference in VI values was found for ANA- patients between RPL women not treated with LMWH and the treated ones (p = 0,01), which have lower VI values and similar to controls. By considering only ANA- treated and not treated RPL patients, the ROC curve shows an area of 0,80 and at the VI cut-off of 11,08 a sensitivity of 85% and a specificity of 67%.

CONCLUSIONS

LMWH could exert a potential beneficial effect in restoring the physiological blood flow supply in terms of VI in uRPL ANA- status, suggesting to include ANA and VI investigations in the RPL diagnostic algorithm in a research context, since further studies are needed to clarify this challenging hypothesis in order to try to ameliorate ANA and abnormal placental vascularization negative influence on RPL pregnancy outcome .

Methodology of preparation of corrosive specimens from human placenta - A technical note

Detailed knowledge of the anatomy of human placenta vessels is clinically essential and requires the use of many different anatomical and histological techniques. One of the interesting methods of visualising vessels is the corrosion technique. It enables spatial visualisation of the vascular network of the analysed organ. The authors present a developed, own method of preparing the corrosive preparations from human placenta. They underline the advantages and disadvantages of this technique. They describe solutions aimed at reducing the costs of the process. They show that corrosion technology enables relatively fast and inexpensive visualisation of arterial and venous vessels of the human placenta.

Comparison of Placental Three-Dimensional Power Doppler Vascular Indices and Placental Volume in Pregnancies with Small for Gestational Age Neonates

This prospective observational study aimed to compare the changes in placental vascular indices and placental volume using three-dimensional power Doppler (3DPD) ultrasound in pregnancies with small for gestational age (SGA) neonates. We enrolled 396 women with singleton pregnancies from September 2013 to June 2016. Placental vascular indices, including the vascularization index (VI), flow index (FI), and vascularization flow index (VFI), and placental volume were obtained using 3DPD ultrasound in the first and second trimesters. Of the enrolled women, 21 delivered SGA neonates and 375 did not. In the first trimester, the SGA group had a significantly lower mean FI (25.10 ± 7.51 versus 33.10 ± 10.97, p < 0.001) and VFI (4.59 ± 1.95 versus 6.28 ± 2.35, p = 0.001) than the non-SGA group. However, there was no significant difference in the placental volume between the two groups during the first trimester. In the second trimester, the SGA group also had a significantly lower mean FI (27.08 ± 7.97 versus 31.54 ± 11.01, p = 0.022) and VFI (6.68 ± 1.71 versus 8.68 ± 3.09, p < 0.001) than the non-SGA group. In addition, a significantly smaller placental volume was noted in the SGA group (104.80 ± 24.23 cm³ versus 122.67 ± 26.35 cm³, p = 0.003) than in the non-SGA group during the second trimester. The results showed that a decreased placental VFI occurred earlier than a decreased placental volume in SGA pregnancies.

Differences in placental capillary shear stress in fetal growth restriction may affect endothelial cell function and vascular network formation

Fetal growth restriction (FGR) affects 5-10% of pregnancies, leading to clinically significant fetal morbidity and mortality. FGR placentae frequently exhibit poor vascular branching, but the mechanisms driving this are poorly understood. We hypothesize that vascular structural malformation at the organ level alters microvascular shear stress, impairing angiogenesis. A computational model of placental vasculature predicted elevated placental micro-vascular shear stress in FGR placentae (0.2 Pa in severe FGR vs 0.05 Pa in normal placentae). Endothelial cells cultured under predicted FGR shear stresses migrated significantly slower and with greater persistence than in shear stresses predicted in normal placentae. These cell behaviors suggest a dominance of vessel elongation over branching. Taken together, these results suggest (1) poor vascular development increases vessel shear stress, (2) increased shear stress induces cell behaviors that impair capillary branching angiogenesis, and (3) impaired branching angiogenesis continues to drive elevated shear stress, jeopardizing further vascular formation. Inadequate vascular branching early in gestation could kick off this cyclic loop and continue to negatively impact placental angiogenesis throughout gestation.

Three-dimensional Doppler ultrasonography for the assessment of fetal liver vascularization in fetuses with intrauterine growth restriction

OBJECTIVE

To demonstrate changes in hepatic volume and vascular indices in fetuses with intrauterine growth restriction (IUGR) compared with normal-growth fetuses, using a noninvasive method (three-dimensional power Doppler ultrasound).

METHODS

The present cross-sectional study was conducted between September 1 and November 30, 2014, at a maternal-fetal medicine unit in Bogotá, Colombia; it included consecutive women at 24-34 weeks of pregnancy. The fetal liver volume and indices of hepatic vascularization were determined with three-dimensional power Doppler ultrasonography and compared between fetuses with and without a diagnosis of IUGR. Results A total of 119 women met study inclusion criteria; 97 fetuses had no growth restriction, whereas 22 fetuses had IUGR. The latter group had decreased liver volume (57.85 ± 29.71 mL vs 86.99 ± 31.24 mL; P=0.010) and increased vascular indices (vascularization index, 47.92 ± 34.44 versus 22.46 ± 18.95; flow index, 71.39 ± 42.01 versus 41.11 ± 23.24; vascularization flow index, 47.94 ± 47.96 versus 13.67 ± 22.38; P=0.003 for all comparisons).

CONCLUSION

Liver volume was decreased and liver vascular indices values were increased in fetuses with IUGR. These findings imply that evaluation of hepatic vascularization with three-dimensional hepatic Doppler could be useful in the diagnosis of IUGR.

Three-dimensional power Doppler ultrasound evaluation of placental blood flow in normal monochorionic diamniotic twin pregnancies

Background

Monochorionic diamniotic (MCDA) twin pregnancies are at higher risk of adverse outcomes and complications, which are attributed to the influence of placental morphology in MCDA twins. Monitoring of placental function is an important index for clinical decisions. The aim of our study was to evaluate the placental blood flow estimated using three-dimensional power Doppler (3D-PD) ultrasound and the vascular indices distribution with gestational age (GA) in normal MCDA twin pregnancies.

Methods

One hundred four MCDA twin pregnancies and 106 singleton pregnancies (GA range, 14–32 weeks) were included in this prospective study. 3D-PD volume data of each fetus was obtained separately from the placenta at the site of umbilical cord insertion. We analyzed the volume data using sonobiopsy technique. The placental vascularization index (VI), flow index (FI) and vascularizationflow index (VFI), were auto-calculated. The means and standard deviation values of three vascular indices per fetus were calculated and regression analysis of the vascular indices as a function of GA was performed in twin pregnancies. The vascular indices of twin and singleton pregnancies were compared using independent t-test.

Results

There were no significant differences in VI, FI or VFI among the fetuses of twins (p > 0.05). These vascular indices increased over the course of pregnancy (p < 0.05). We obtained the regression equations for the indices as a function of GA in days: VI = exp. (4.369–28.533/GA) (R² = 0.699, p < 0.05), FI = exp. (3.916–13.003/GA) (R² = 0.511, p < 0.05), and VFI = exp. (3.577–37.468/GA) (R² = 0.675, p < 0.05). There were no significant differences in three vascular indices between MCDA twin and singleton groups (p > 0.05).

Conclusions

3D-PD placental data using sonobiopsy technique could reflect the placental blood flow of each twin, which could be applied to the study of placental perfusion in MCDA twin pregnancies. This study also presented the vascular indices distribution with GA in normal twin pregnancies, which might be useful for early detection of MCDA complications.

Effect of chorionic villus sampling on placental volume and vascularization in the first trimester of pregnancy

Objective: To evaluate the effects of chorionic villus sampling (CVS) on placental volume (PV), perfusion, and vasculature in the first trimester of pregnancy.Method: Uterine artery pulsatility index (PI), PV, vascularization index (VI), flow index (FI), and Vascularization Flow Index (VFI) were serially measured in 38 pregnant women who underwent CVS. Thirty-eight women who did not undergo invasive prenatal diagnosis were recruited as controls.Results: CVS was associated with a mild reduction of PI, a reduction of placental VI, FI, and VFI and with an increase in PV detected one week after the procedure. The outcome of pregnancy was similar between women of the two groups.Conclusion: Our findings showed that CVS is associated with mild placental vascular and morphological changes. However, these changes do not seem to be associated with adverse outcome.

MRI features of the placenta in fetuses with and without CNS abnormalities

AIM

To investigate if magnetic resonance imaging (MRI) features of the placenta are different in fetuses with and without central nervous system (CNS) abnormalities.

MATERIAL AND METHODS

Institutional research ethics board approval was obtained. Fetal MRI of 97 singleton pregnancies were analysed retrospectively (19-25 weeks gestation), 65 with CNS morphological abnormalities and 32 controls. Placental T2 signal intensity, placental and fetal volumes, placental-to-fetal volume ratio, and placental apparent diffusion coefficient (ADC) values were assessed. Measurements were compared with the presence or absence of CNS fetal abnormalities using the Mann-Whitney test. Separate slopes models and intercept models were used to check for significant differences in the slopes and intercepts, respectively, among the groups.

RESULTS

Placental ADC values were significantly lower in placentas of fetuses with CNS abnormalities compared to controls (p=0.04). Placental T2 signal intensity, fetal and placental volumes did not differ between the two groups. The rate of increase in fetal-to-placental volume ratio with gestational age (GA) was greater among the controls.

CONCLUSION

The presence of fetal CNS abnormalities is associated with reduced ADC values of the placenta. Moreover, placentas of fetuses with CNS abnormalities show a less rapid increase in fetal to placental volume ratio with GA. Therefore, ADC mapping, as well as different growth kinetics of the placenta relative to the fetus, may potentially serve as early markers of pathological neurodevelopment.

Gestation-Specific Changes in the Anatomy and Physiology of Healthy Pregnant Women: An Extended Repository of Model Parameters for Physiologically Based Pharmacokinetic Modeling in Pregnancy

BACKGROUND

In the past years, several repositories for anatomical and physiological parameters required for physiologically based pharmacokinetic modeling in pregnant women have been published. While providing a good basis, some important aspects can be further detailed. For example, they did not account for the variability associated with parameters or were lacking key parameters necessary for developing more detailed mechanistic pregnancy physiologically based pharmacokinetic models, such as the composition of pregnancy-specific tissues.

OBJECTIVES

The aim of this meta-analysis was to provide an updated and extended database of anatomical and physiological parameters in healthy pregnant women that also accounts for changes in the variability of a parameter throughout gestation and for the composition of pregnancy-specific tissues.

METHODS

A systematic literature search was carried out to collect study data on pregnancy-related changes of anatomical and physiological parameters. For each parameter, a set of mathematical functions was fitted to the data and to the standard deviation observed among the data. The best performing functions were selected based on numerical and visual diagnostics as well as based on physiological plausibility.

RESULTS

The literature search yielded 473 studies, 302 of which met the criteria to be further analyzed and compiled in a database. In total, the database encompassed 7729 data. Although the availability of quantitative data for some parameters remained limited, mathematical functions could be generated for many important parameters. Gaps were filled based on qualitative knowledge and based on physiologically plausible assumptions.

CONCLUSION

The presented results facilitate the integration of pregnancy-dependent changes in anatomy and physiology into mechanistic population physiologically based pharmacokinetic models. Such models can ultimately provide a valuable tool to investigate the pharmacokinetics during pregnancy in silico and support informed decision making regarding optimal dosing regimens in this vulnerable special population.

First trimester placental vascularization and angiogenetic factors are associated with adverse pregnancy outcome

BACKGROUND

Hypertensive disorders, fetal growth restriction and preterm birth are major obstetrical complications and are related to impaired placentation. Early identification of impaired placentation can advance clinical care by preventing or postpone adverse pregnancy outcome.

OBJECTIVES

Determine whether sonographic assessed placental vascular development and concomitant changes in inflammation- and/or angiogenesis-related serumproteins differ in the first trimester between uncomplicated pregnancies and pregnancies with adverse outcome.

STUDY DESIGN

This prospective longitudinal study defines adverse pregnancy outcome as conditions associated with impaired placentation; fetal growth restriction, hypertensive disorder, preterm birth and placental abruption. The vascularization index, flow index, vascularization flow index and placental volume were determined at 8, 10 and 12 weeks pregnancy from 64 women using 3D power Doppler. Serum levels were analyzed for Angiopoetin-1 and -2, Leptin, VEGF-R, VEGF, and EGF.

RESULTS

The vascularization index and vascular flow index increased in uneventful pregnancies with almost 50% between 8 and 12 weeks, resulting in a ∼50% higher vascularization index at 12 weeks compared to women with an adverse pregnancy outcome. Women with an adverse pregnancy outcome (n = 13) had significantly lower indices and placental volumes at all time points measured and these indices did not increase between 8 and 12 weeks. Reduced vascular development was associated with increased Angiopoietin-1 levels at 8 and 12 weeks and increased Leptin levels at 8 weeks.

CONCLUSIONS

Pregnancies with an adverse outcome caused by conditions associated with impaired placentation differ from uneventful pregnancies in having reduced placental vascularization accompanied by elevated circulating levels of Angiopoietin-1 and Leptin already in the first trimester.

Three dimensional power Doppler of the placenta and its clinical applications

The aim of this review is to discuss three dimensional (3D) power Doppler of the placenta and its clinical applications. There is a strong clinical need to develop noninvasive, simple and widely available methods of evaluating in vivo placental function to assess fetal wellbeing. While conventional ultrasound is a proven tool in the evaluation of fetal structural anomalies and health, its ability to assess placental function, especially prior to the onset of fetal compromise, is the subject of ongoing investigation. Three dimensional power Doppler has the ability to detect vascularity and blood flow with greater detail than conventional ultrasound, which has led to its investigation in preeclampsia, fetal growth restriction, and other placental vascular abnormalities. While more data are needed on the optimal imaging protocol and its predictive ability for clinical outcomes, 3D power Doppler is emerging as a promising new technology that will improve the evaluation of placental function.

The alteration in placental volume and placental mean grey value in growth-restricted pregnancies assessed by 3D ultrasound (Growth Restriction & 3D Ultrasonography)

We aimed to evaluate the volumetric and echogenic alterations in placentas between the intrauterine growth restriction (IUGR) and normal pregnancies using three-dimensional ultrasound and virtual organ computer-aided analysis (VOCAL) software. This case-control prospective study consisted of 48 singleton pregnancies complicated by IUGR and 60 healthy singleton pregnancies matched for maternal age, gestational age and parity. Placental volume (PV) and placental volumetric mean grey values (MGV) were evaluated. PV (cm(3)) was analysed using the VOCAL imaging analysis program, and 3D histogram was used to calculate the volumetric MGV (%). PV was 278.50 ± 63.68 and 370.98 ± 97.82 cm(3) in IUGR and control groups, respectively (p = 0.004). MGV of the placenta was 38.24 ± 8.41 and 38.24 ± 8.41 in IUGR and control groups, respectively (p = 0.30). receiver operator curve (ROC) curve analysis revealed that area under curve was 0.731 for PV. Correlation analysis revealed that PV was significantly associated with estimated fetal weight (r = 0.319, p = 0.003), biparietal diameter (r = 0.346, p = 0.002), head circumference (r = 0.269, p = 0.019), abdominal circumference (r = 0.344, p = 0.002) and femur length (r = 0.328, p = 0.004). PV was inversely related to the umbilical artery pulsatility index (r = - 0.244, p = 0.017). To the best of our knowledge, this is the first study evaluating volumetric MGV in IUGR placentas by comparing them with healthy pregnancies. Our study showed that PV diminishes significantly in IUGR pregnancies, whereas volumetric MGV does not alter significantly.

Influence of Pulse Repetition Frequency on 3-D Power Doppler Quantification

Three-dimensional power Doppler quantification has limited application because of its high dependency on attenuation. The purpose of the study described here was to assess if different degrees of attenuation, depending on pulse repetition frequency (PRF) adjustment, alter 3-D power Doppler quantification in a region of 100% moving blood when using vascularization index, flow index and vascularization flow index (VFI). A cubic-shaped gelatin phantom with a 1.8-mm-internal-diameter silicon tube was used. The tube, placed at 45° to the phantom's surface, was filled with blood-mimicking fluid with as constant maximum velocity of 30 cm/s. Two different attenuation blocks (low and high attenuation) were alternatively placed between the phantom and the transvaginal transducer. One single observer acquired 10 data sets for each PRF level from 0.3 to 7.5 kHz, using the high- and low-attenuation blocks, for a total of 200 3-D power Doppler data sets. We assessed VFI from 1.5-mm-diameter spherical samples, virtually placed inside the tube, always at the same position. No difference was noted between high- and low-attenuation VFI values when using a PRF of 0.3 kHz. As PRF increased, it was observed that VFI quantification progressively differed between low and high attenuation. Also, a slope on VFI values for both high- and low-attenuation models could be observed when increasing PRF, particularly above 4.0 kHz. We concluded that PRF adjustment is very relevant when using VFI to quantify 3-D power Doppler signal.

Reduced placental volume and flow in severe growth restricted fetuses

OBJECTIVES

To evaluate placental volume and vascular indices in pregnancies with severe fetal growth restriction and determine their correlations to normal reference ranges and Doppler velocimetry results of uterine and umbilical arteries.

METHODS

Twenty-seven fetuses with estimated weights below the 3rd percentile for gestational age were evaluated. Placental volume and vascular indices, including vascularization, flow, and vascularization flow indices, were measured by three-dimensional ultrasound using a rotational technique and compared to a previously described nomogram. The observed-to-expected placental volume ratio for gestational age and observed-to-expected placental volume ratio for fetal weight were calculated. Placental parameters correlated with the Doppler velocimetry results of uterine and umbilical arteries.

RESULTS

The mean uterine artery pulsatility index was negatively correlated with the observed-to-expected placental volume ratio for gestational age, vascularization index and vascularization flow index. The observed-to-expected placental volume ratio for gestational age and observed-to-expected placental volume ratio for fetal weight and vascularization index were significantly lower in the group with a bilateral protodiastolic notch. No placental parameter correlated with the umbilical artery pulsatility index.

CONCLUSIONS

Pregnancies complicated by severe fetal growth restriction are associated with reduced placental volume and vascularization. These findings are related to changes in uterine artery Doppler velocimetry. Future studies on managing severe fetal growth restriction should focus on combined results of placental three-dimensional ultrasound and Doppler studies of uterine arteries.

Utero-placental vascularisation in normal and preeclamptic and intra-uterine growth restriction pregnancies: third trimester quantification using 3D power Doppler with comparison to placental vascular morphology (EVUPA): a prospective controlled study

INTRODUCTION

Preeclampsia (PE) and intra-uterine growth restriction (IUGR) are two major pregnancy complications related to chronic utero-placental hypoperfusion. Three-dimensional power Doppler (3DPD) angiography has been used for the evaluation of utero-placental vascularisation and three vascular indices have been calculated: the vascularisation index (VI), flow index (FI) and vascularisation-FI (VFI). However, several technical endpoints hinder the clinical use of 3DPD as physical characteristics and machine settings may affect 3DPD indices, and so its clinical significance is not yet clear.

OBJECTIVES

The primary objective is to better understand the clinical significance of 3DPD indices by evaluating the relationship between these indices and placental morphometry. Secondary objectives are (i) to determine the impact of machine settings and physical characteristics on 3DPD indices, and (ii) to evaluate physio-pathological placental vascularisation patterns.

METHODS AND ANALYSIS

This is a prospective controlled study. We expect to include 112 women: 84 with normal pregnancies and 28 with PE and/or IUGR (based on our former cohort study on 3DPD indices for PE and/or IUGR prediction (unpublished data)). Within 72 h before planned or semi-urgent caesarean section, utero-placental 3DPD images with five different machine settings will be acquired. Placentas will be collected and examined after surgery and stereological indices (volume density, surface density, length density) calculated. The 3DPD indices (VI, FI and VFI) of the placenta and adjacent myometrium will be calculated. Correlation between Doppler and morphological indices will be evaluated by Pearson or Spearman tests. Agreement between 3DPD indices and morphological indices will be assessed by Bland and Altman plots. The impact of Doppler settings and maternal characteristics on 3DPD indices will be evaluated with a multivariate linear regression model.

ETHICS

The study and related consent forms have been approved by the French Ethics Committee (CPP, Comité de Protection des Personnes) Est III on 4 March 2014.

Placental vascular indices (VI, FI and VFI) in intrauterine growth retardation (IUGR). A pooled analysis of the literature

OBJECTIVE

I performed a systematic review and pooled analysis to study the utility of the placental vascular flow indices vascularization index (VI), flow index (FI) and vascularization flow index (VFI) in the prediction or identification of in-utero growth restriction (IUGR).

METHOD

A comprehensive literature search for relevant studies was conducted using PubMed and Web of Knowledge databases. Included were cohort or case-control studies which reported (1) the statistical position and dispersion of vascular indices in a population of normal pregnancies at various trimesters of pregnancy; (2) correlation between vascular indices and gestational age; or (3) the vascular index values stratified according to the presence of SGA/IUGR versus a population of controls.

RESULTS

Seven studies met the criteria of inclusion, for a total of 788 controls and 82 SGA cases in the first trimester, and 169 controls and 80 IUGR cases essentially enrolled in the 3rd trimester. After normalization of the means, the pooled detection rates (DRs) at a 10% false positive rate were 32.5%, 53.8% and 51.0%, respectively, for the vascular indices VI, FI and VFI in the third trimester. No significant discriminant ability was detected in the first trimester.

CONCLUSION

A significant DR for IUGR was demonstrated only in the third trimester, thus limiting the utility of vascular indices to predict IUGR. VI and VFI are more reliable and yield better DR and better performance in terms of homogeneity than FI and should be evaluated in the management of third trimester IUGR and prediction of outcome.

Placental vascularization alterations in hypertensive disorders complicating pregnancy (HDCP) and small for gestational age with HDCP using three-dimensional power doppler in a prospective case control study

Background

Hypertensive disorders complicating pregnancy (HDCP) continues to be a leading cause of maternal and neonatal mortality and morbidity. The clinical value of placental three-dimensional power Doppler (3DPD) in assessing HDCP requires further confirmation. The research was developed to assess changes of placental vascularity in HDCP using 3DPD and to investigate the placental vascularity in small for gestational age (SGA) compared with not-SGA in patients with HDCP.

Methods

There were 126 normotensive and 128 hypertensive pregnant women included in this prospective case–control study from March 2011 to March 2013. Pregnant women underwent 3DPD. Vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were obtained. The placental 3DPD indices, umbilical artery systolic and diastolic ratio (S/D) and pregnancy outcomes were compared between the groups.

Results

The placental VI and VFI were significantly lower in hypertensive women compared with normotensive women (P < 0.001 and P = 0.014, respectively), and these parameters were significantly reduced in severe preeclampsia (P < 0.001 and P = 0.003, respectively). A weak correlation was found between VI and umbilical artery S/D in HDCP group (r = -0.277, P = 0.001). In HDCP population, neonates who were postnatally diagnosed with SGA had lower VI (P = 0.041) and higher S/D (P < 0.001).

Discussion

The placental vascularity indices decreased in hypertensive women and the reduction inplacental perfusion was consistent with the severity of the hypertensive disorder. The associations betweenplacental vascularization and umbilical artery impedance may be valuable for further researches and arerequired confirmation. The significant differences in the 3DPD placental vascularization between SGA andnot-SGA in hypertensive pregnancy population may show some clinical importance that we could use tobetter assess or predict the progression and adverse outcomes in the future. Although 3DPD quantificationhas been widely used in multiple publications, we have to acknowledge its limitations.

Conclusions

The intraplacental vascularization was poor in HDCP, and especially in severe preeclampsia. Neonates with SGA had poor placental vascularization and higher umbilical artery S/D. Further studies should focus on the clinical assessment of placental 3DPD as well as a combination of placental 3DPD and other fetal Doppler indices to better predict the development and outcomes of preeclampsia.

Placental Volumetry by 2-D Sonography with a New Mathematical Formula: Prospective Study on the Shell of a Spherical Sector Model

The aim of this study was to determine the utility of a new mathematical model in volumetric assessment of the placenta using 2-D ultrasound. Placental volumetry was performed in a prospective cross-sectional survey by virtual organ computer-aided analysis (VOCAL) with the help of a shell-off method in 346 uncomplicated pregnancies according to STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) guidelines. Furthermore, placental thickness, length and height were measured with the 2-D technique to estimate placental volume based on the mathematical formula for the volume of "the shell of the spherical sector." Fetal size was also assessed by 2-D sonography. The placental volumes measured by 2-D and 3-D techniques had a correlation of 0.86. In the first trimester, the correlation was 0.82, and later during pregnancy, it was 0.86. Placental volumetry using "the circle-shaped shell of the spherical sector" mathematical model with 2-D ultrasound technique may be introduced into everyday practice to screen for placental volume deviations associated with adverse pregnancy outcome.

Improving amino acid nutrition to prevent intrauterine growth restriction in mammals

Intrauterine growth restriction (IUGR) is one of the most common concerns in human obstetrics and domestic animal production. It is usually caused by placental insufficiency, which decreases fetal uptake of nutrients (especially amino acids) from the placenta. Amino acids are not only building blocks for protein but also key regulators of metabolic pathways in fetoplacental development. The enhanced demands of amino acids by the developing conceptus must be met via active transport systems across the placenta as normal pregnancy advances. Growing evidence indicates that IUGR is associated with a reduction in placental amino acid transport capacity and metabolic pathways within the embryonic/fetal development. The positive relationships between amino acid concentrations in circulating maternal blood and placental amino acid transport into fetus encourage designing new therapies to prevent or treat IUGR by enhancing amino acid availability in maternal diets or maternal circulation. Despite the positive effects of available dietary interventions, nutritional therapy for IUGR is still in its infancy. Based on understanding of the underlying mechanisms whereby amino acids promote fetal growth and of their dietary requirements by IUGR, supplementation with functional amino acids (e.g., arginine and glutamine) hold great promise for preventing fetal growth restriction and improving health and growth of IUGR offspring.

Three-dimensional ultrasonographic placental volume in gestational diabetes mellitus

OBJECTIVES

We aimed to evaluate the placental volume and placental mean gray value in gestational diabetes mellitus (GDM) and healthy placentas using three-dimensional (3D) ultrasound and Virtual Organ Computer-aided AnaLysis (VOCAL).

METHODS

This case-control prospective study consisted of 39 singleton pregnancies complicated by GDM and 42 healthy singleton pregnancies matched for gestational age, maternal age and parity. Placental volume and placental volumetric mean gray values were evaluated. The placental volume (cm(3)) was analyzed using the VOCAL imaging analysis program and 3D histogram was used to calculate the volumetric mean gray value (%).

RESULTS

Placental volume was significantly larger in GDM (411.59 ± 170.82 versus 343.86 ± 128.94 cm(3); p = 0.046). There was no significant difference in mean gray value between GDM and healthy placentas (36.65 ± 7.02 versus 38.71 ± 7.91, respectively; p = 0.277). Placental volume was significantly correlated with gestational week (r = 0.219, p = 0.035) and parity (r = 0.228, p = 0.048). There was negative significant relation between placental volume and umbilical artery systolic/diastolic ratio, pulsatility index and resistance index (r = -0.278, p = 0.007; r = -0.315, p = 0.002; r = -0.322, p = 0.001, respectively).

CONCLUSIONS

Placental volume increases significantly in GDM, whereas mean gray values do not alter significantly. These data may reflect the placental changes in GDM placentas that may help to understand the pathophysiology better.

Advanced MR imaging of the placenta: Exploring the in utero placenta-brain connection

The placenta is a vital organ necessary for the healthy neurodevelopment of the fetus. Despite the known associations between placental dysfunction and neurologic impairment, there is a paucity of tools available to reliably assess in vivo placental health and function. Existing clinical tools for placental assessment remain insensitive in predicting and evaluating placental well-being. Advanced MRI techniques hold significant promise for the dynamic, non-invasive, real-time assessment of placental health and identification of early placental-based disorders. In this review, we summarize the available clinical tools for placental assessment, including ultrasound, Doppler, and conventional MRI. We then explore the emerging role of advanced placental MR imaging techniques for supporting the developing fetus and appraise the strengths and limitations of quantitative MRI in identifying early markers of placental dysfunction for improved pregnancy monitoring and fetal outcomes.

Examination of placental three-dimensional power Doppler indices and perinatal outcome in pregnancies complicated by intrauterine growth restriction

OBJECTIVE

To examine placental vascularization using three-dimensional power Doppler (3DPD) ultrasonography in pregnancies complicated by intrauterine growth restriction (IUGR).

METHODS

The present prospective study was conducted at the University of Szeged (Szeged, Hungary) from February 2012 to March 2013. Women with a singleton pregnancy who attended the maternity outpatient ward in the second or third trimester were enrolled consecutively. Women were divided into two groups: those with a normal pregnancy and those with a pregnancy complicated by IUGR. Three 3DPD indices-vascularization index (VI), flow index (FI), and vascularization flow index (VFI)-were assessed.

RESULTS

A total of 223 women were enrolled: 171 were in the control group and 52 in the IUGR group. Median VI was 3.7% (interquartile range [IQR] 3.2%-4.2%) in the IUGR group and 10.1% (IQR 8.6%-10.9%) in the control group (P=0.001). Median FI was 40.0 (IQR 39.7-42.5) in the IUGR group and 45.1 (IQR 44.1-53.1) in the control group (P=0.012). Median VFI was 2.2 (IQR 2.1-2.4) in the IUGR group and 4.8 (IQR 4.4-5.3) in the control group (P<0.001).

CONCLUSION

Placental vascularization was reduced in pregnancies complicated by IUGR.

First-trimester 3D power Doppler of the uteroplacental circulation space and fetal growth restriction

OBJECTIVE

The objective of the study was to compare the 3-dimensional power Doppler (3DPD) of the uteroplacental circulation space in the first trimester between women who subsequently deliver growth-restricted vs normally grown neonates.

STUDY DESIGN

This was a prospective observational study of singleton pregnancies at 11-14 weeks' gestation. The 3DPD indices, vascularization index, flow index, and vascularization flow index were determined on a uteroplacental circulation space sphere biopsy with the virtual organ computer-aided analysis program. Growth restriction was defined as a birthweight less than the 10th percentile for gestational age and was evaluated using both population-based and customized birth curves.

RESULTS

Five hundred seventy-seven women were enrolled. Five hundred twenty-six were eligible for analysis using population centiles, and 497 were available for evaluation using customized centiles. There was no difference in the first-trimester 3DPD indices between patients with growth-restricted and normally grown neonates using either curve.

CONCLUSION

Three-dimensional power Doppler indices of the uteroplacental circulation space in the first trimester are similar between neonates who develop growth restriction and those who will grow normally.

Second-trimester placental volume and vascular indices in the prediction of small-for-gestational-age neonates

OBJECTIVE

To evaluate the ability of second-trimester placental volume and vascular indices to predict small-for-gestational-age (SGA) birth weight pregnancies.

MATERIAL AND METHODS

Women with singleton pregnancies were prospectively evaluated at 17-20 weeks of gestation. Second-trimester placental volume and vascular indices were obtained and calculated using volume organ computer-aided analysis and three-dimensional (3D) power Doppler ultrasound. Participants were followed until delivery and their medical records were reviewed, including maternal age, parity and pregestational body weight and body height, as well as the gestational age, birth weight and gender of the fetus.

RESULTS

Of the 163 women with complete follow-up, 20 gave birth to SGA and 143 to appropriate-for-gestational-age (AGA) neonates. The mean second-trimester placental volume was significantly lower in the SGA than in the AGA group (170.6 ± 49.8 vs. 213.5 ± 75.8 cm(3), p = 0.015). None of the vascular indices, including the vascularization index, flow index and vascularization flow index, differed significantly between the two groups. We also found that the optimum cutoff for placental volume at a gestational age of 17-18 weeks was 189.7 cm(3).

DISCUSSION

Second-trimester placental volume was positively correlated with neonatal birth weight. Second-trimester placental volume measured on 3D ultrasound may be predictive of SGA neonates.

[Placental 3D Doppler angiography: current and upcoming applications]

The placental dysfunction, which seems to be caused by a defect of trophoblastic invasion and impaired uterine vascular remodeling since the first trimester, is responsible in a non-exclusive way for the chronic placental hypoxia, resulting secondarily in the intra-uterine growth restriction (IUGR) and/or pre-eclampsia (PE). The quality of utero-placental vasculature is essential for a proper fetal development and a successful progress of pregnancy. However, the in vivo assessment of placental vascularization with non-invasive methods is complicated by the small size of placental terminal vessel and its complex architecture. Moreover, imaging with contrast agent is not recommended to pregnant women. Until recently, the fetal and maternal vascularization could only be evaluated through pulse Doppler of uterine arteries during pregnancy, which has little clinical value for utero-placental vascularization defects assessment. Recently, a non-invasive study, without use of contrast agent for vasculature evaluation of an organ of interest has become possible by the development of 3D Doppler angiography technique. The objective of this review was to make an inventory of its current and future applications for utero-placental vasculature quantification. The main findings of the literature on the assessment of utero-placental vascularization in physiological situation and major placental vascular dysfunction pathologies such as PE and IUGR were widely discussed.

Three-dimensional placental volume and mean grey value: Normal ranges in a Turkish population and correlation with maternal serum biochemistry and Doppler parameters

The aim of this study is to evaluate the relationship between three-dimensional (3D) ultrasound measurements of placenta at 11-13(6) weeks' gestation and maternal serum levels of pregnancy associated plasma protein-A (PAPP-A), free beta human chorionic gonadotrophin (fβhCG), Doppler parameters in early pregnancy. This prospective study consisted of 334 singleton pregnancies at 11-13(6) weeks' gestation. Placental volume and placental volumetric mean grey values were evaluated. The placental volume (cm(3)) was analysed using the Virtual Organ Computer-aided AnaLysis (VOCAL) imaging program and 3D histogram was used to calculate the volumetric mean grey value (%). Mean maternal age was 28.35 ± 7.55. Mean gestational age was 12.29 ± 0.68 weeks. Placental volume was 77.04 ± 35.74 cm(3). Mean grey value of the placenta was 34.38 ± 8.02%. Correlation analysis revealed that placental volume was significantly correlated with the crown-rump length (r = 0.173, p = 0.002), gestational week (r = 0.116, p = 0.036), ductus venosus pulsatility index (r = -0.101, p = 0.04) and maternal weight (r = 0.099, p = 0.037). There was a significant relation between the mean grey value of the placenta and maternal age (r = 0.131, p = 0.02), nuchal translucency (r = -0.109, p = 0.048), PAPP-A (r = 0.108, p = 0.04) and fβhCG (r = 0.104, p = 0.042). Volumetry of the placenta can be carried out with a high percentage of 1st trimester pregnancies. Volumetry during the 1st trimester could be helpful because of the less advanced state of placentation. This examination is easy to perform and the measurements can be acquired correctly and quickly.

Role of 3-dimensional power Doppler sonography in differentiating pregnant women with threatened preterm labor from those with an asymptomatic short cervix

OBJECTIVES

To compare cervical volumes and vascularization indices using 3-dimensional power Doppler sonography among singleton pregnancies with threatened preterm labor and an asymptomatic short cervix.

METHODS

Three hundred asymptomatic healthy pregnant women between 24 and 34.6 gestational weeks were prospectively scanned for cervical length. If cervical length was short, defined as below the 10th percentile for gestational age, the cervical volume and vascularization indices (vascularization index [VI], vascularization-flow index [VFI], and flow index [FI]) were measured. Women receiving any treatment for preterm delivery prevention were excluded. During this period, the same sonographic parameters were measured among patients with threatened preterm labor admitted to our institution during the first 24 hours after admission. Multiple pregnancies and fetal or maternal pathologic conditions, were exclusion criteria. Data on body mass index, maternal age, smoking, parity, family history of preterm birth, mother who was born preterm, and previous preterm birth among the pregnant women were recorded. Sonographic and medical history parameters were compared between the two groups.

RESULTS

Twenty-nine asymptomatic healthy women (9.6%) had a short cervix. Additionally, 71 pregnancies with threatened preterm labor were scanned. There were no statistically significant differences between the groups in medical history parameters or cervical length. The cervical volume was smaller in threatened preterm cases (12.90 versus 17.168 cm(3); P = .005). The VI and VFI were lower in women with an asymptomatic short cervix (VI, 4.369% versus 15.939%; P < .001; VFI, 1.514 versus 4.878; P < .001). The FI was higher in the short cervix group (33.581 versus 30.311; P = .006).

CONCLUSIONS

Three-dimensional transvaginal sonography reveals differences in cervical volume and vascularization indices between pregnancies with an asymptomatic short cervix and cases with threatened preterm labor, although cervical length is similar in both groups.

Quantitative assessment of placental vasculature and placental volume in normal pregnancies with the use of 3D Power Doppler

PURPOSE

The aim of the study was to determine reference values for placental vascular indices and placental volume according to gestational age.

MATERIAL/METHODS

The assessment of placental vascular indices and placental volume using 3D Power Doppler and the Virtual Organ Computer-aided Analysis (VOCAL) technique was performed on 100 normal fetuses between 22 and 41 weeks of gestation. In this study the method of the individual setting of the power Doppler gain value was used. Only patients with entirely visualized placenta were included in the study.

RESULTS

No statistically relevant difference in the values of placental vascular indices and placental volume between different localizations of the placenta was detected. No statistically significant changes to placental vascular indices depending on gestational age were found. It enabled to determine the 10th, 50th and 90th percentile values for the vascularization index (VI), flow index (FI), vascularization-flow index (VFI), which are independent of gestational age. No correlation was found between placental volume and placental vascular indices.

CONCLUSIONS

The values of placental vascular indices are constant between the 22nd and 41st week of a normal pregnancy. Placental volume measured with the use of the VOCAL program increases between 22nd and 41st week of a normal pregnancy. In a normal pregnancy the placental vasculature increases adequately to the increase of its volume. The method of the individual setting of the power Doppler gain value makes it possible to achieve comparable values of placental vascular indices regardless of the distance between the probe and the placenta.

MANAGEMENT OF REDUCED FETAL MOVEMENTS

Reduced fetal movement (RFM) is commonly defined as any reduction in maternal perception of fetal activity. Perceived fetal activity may be movement of limbs, trunk or head movement, but excludes fetal hiccoughs (as this is involuntary movement). The perception of fetal movement by an expectant mother is the first, and ongoing, non-sonographic indicator of fetal viability. The “normal” pattern of fetal movements varies from pregnancy to pregnancy, and often does not become established until 28 weeks’ gestation. Many babies have particularly active periods of the day, usually corresponding to periods of maternal rest and inactivity (which may in itself reflect increased maternal awareness of fetal movement). A variable percentage of sonographically observed fetal movements are perceived by prospective mothers (commonly 30–40%, although some studies report rates as high as 80%).

Sildenafil citrate increases fetal weight in a mouse model of fetal growth restriction with a normal vascular phenotype

Fetal growth restriction (FGR) is defined as the inability of a fetus to achieve its genetic growth potential and is associated with a significantly increased risk of morbidity and mortality. Clinically, FGR is diagnosed as a fetus falling below the 5(th) centile of customised growth charts. Sildenafil citrate (SC, Viagra™), a potent and selective phosphodiesterase-5 inhibitor, corrects ex vivo placental vascular dysfunction in FGR, demonstrating potential as a therapy for this condition. However, many FGR cases present without an abnormal vascular phenotype, as assessed by Doppler measures of uterine/umbilical artery blood flow velocity. Thus, we hypothesized that SC would not increase fetal growth in a mouse model of FGR, the placental-specific Igf2 knockout mouse, which has altered placental exchange capacity but normal placental blood flow. Fetal weights were increased (by 8%) in P0 mice following maternal SC treatment (0.4 mg/ml) via drinking water. There was also a trend towards increased placental weight in treated P0 mice (P = 0.056). Additionally, 75% of the P0 fetal weights were below the 5(th) centile, the criterion used to define human FGR, of the non-treated WT fetal weights; this was reduced to 51% when dams were treated with SC. Umbilical artery and vein blood flow velocity measures confirmed the lack of an abnormal vascular phenotype in the P0 mouse; and were unaffected by SC treatment. (14)C-methylaminoisobutyric acid transfer (measured to assess effects on placental nutrient transporter activity) per g placenta was unaffected by SC, versus untreated, though total transfer was increased, commensurate with the trend towards larger placentas in this group. These data suggest that SC may improve fetal growth even in the absence of an abnormal placental blood flow, potentially affording use in multiple sub-populations of individuals presenting with FGR.

Endothelial eNOS/arginase imbalance contributes to vascular dysfunction in IUGR umbilical and placental vessels

Placental vascular tone is critically influenced by nitric oxide (NO) derived from endothelial NO synthase (eNOS) activity. Placental vessels from pregnancies complicated with intrauterine growth restriction present altered NOS-dependent vasodilation. Arginase-2 competes with eNOS for l-arginine and counteracts the NOS-dependent relaxation in umbilical vessels from normal pregnancies. However there is no data regarding the contribution of arginase activity on the impaired endothelial function in IUGR placenta. We studied whether arginase-2 participates in IUGR-related placental vascular dysfunction counteracting eNOS-dependent relaxation, and the regulation of arginase-2 and eNOS expression in endothelial cells from IUGR umbilical arteries (HUAEC) and veins (HUVEC). In IUGR-derived umbilical arteries (UA) and veins (UV), and chorionic arteries (CA), NOS-dependent vasoactive response in the presence and absence of BEC (arginase inhibitor) was studied. Protein levels of eNOS (total and Ser(1177)-P-eNOS), arginase-2 and arginase activity were determined in IUGR HUAEC and HUVEC. In IUGR vessels eNOS-dependent relaxation was reduced, being improved by BEC. This effect was higher in arteries than veins, and in chorionic compared with umbilical vessels. In cultured IUGR endothelial cells, arginase-2 protein expression and activity were increased in HUVEC, without changes in HUAEC. In IUGR-derived endothelium there was a generalized reduction in the in vitro eNOS activation (Ser(1177)-P-eNOS/eNOS), and therefore a decreased eNOS/arginase activity ratio. Here we provide ex vivo and in vitro evidence for a vascular role of arginase throughout placental vasculature, negatively controlling NOS activity. This effect seems to be crucial in the pathophysiology of endothelial dysfunction present in IUGR feto-placental vessels.

Two-dimensional and three-dimensional Doppler assessment of fetal growth restriction with different severity and onset

OBJECTIVES

To investigate the role of three-dimensional (3D) power Doppler ultrasonography in the assessment of fetal growth-restriction (FGR) with various degrees of severity and onset, and compare the results with the analysis of two-dimensional (2D) Doppler.

STUDY DESIGN

Vascular indices extracted from 3D Doppler measurements of the placenta were compared with indices of flow-velocity waveforms extracted from 2D Doppler measurements of the major sites of the fetal circulation between FGR (study group) and uncomplicated pregnancies (control group) from 25 to 38 weeks' gestation.

RESULTS

Three-dimensional indices were significantly lower in pregnancies complicated by FGR compared with uncomplicated pregnancies. When measured in placental periphery, vascularization index was 9.4 ± 9.6 in FGR pregnancies compared with 16 ± 14.7, P = 0.04. Flow index was 33.9 ± 6.9 compared with 38.7 ± 4.9, P = 0.03 and the vascularization-flow index was 3.8 ± 4.3 compared with 6.5 ± 6, respectively, P = 0.03. Among the conventional 2D indices, umbilical artery and middle cerebral artery pulsatility indices were not significantly different between the FGR and control groups. Higher rate of maternal or fetal compartment vascular lesions were detected in the FGR group.

CONCLUSIONS

Three-dimensional Doppler was found to be more strongly associated with placental vascular compromise than conventional 2D Doppler, regardless of severity and onset of fetal growth restriction.