Uterine artery Doppler velocimetry in pregnant women with hypertension

Comparison of Placental Location on Ultrasound in Preeclampsia and Normotensive Pregnancy in Third Trimester

Background

Hypertensive disorders in pregnancy account for 15%-20% maternal and 20%-25% perinatal mortality. There is interest in predicting preeclampsia (PE) early in pregnancy to reduce PE and its subsequent complications. There is no cheap and easily available, reliable predictor for PE. Some studies have shown that the lateral location of placenta is associated with adverse pregnancy outcomes due to PE. The lateral placenta is yet to be proven as a strong predictor of PE to initiate preventive measures. Placental localization can be easily done on routine ultrasonography during pregnancy. In the light of these observations, a prospective study was done to study any association between PE and placental location by ultrasound in third trimester. Research Question: Is there any association between placental location on ultrasound and preeclampsia in third trimester? The objective is to study association between location of placenta and preeclampsia and compare placental location in normotensive pregnancies with that in PE in third trimester.

Methods

A prospective comparative, case-control, observational study was conducted in the Department of Obstetrics and Gynecology at North DMC Medical College and Hindu Rao Hospital, Delhi, India, from August 2019 to April 2020. The study population included 200 pregnant women with singleton pregnancy in third trimester, without any medical disorders such as diabetes mellitus, hypertension, renal disease, cardiac disease, and coagulation disorder or smoking. One hundred women had preeclampsia and 100 were normotensive controls. Ultrasound was done after filling F form as per the Government of India guidelines to rule out sex determination, and placenta was localized by ultrasound. Placenta was classified as central when it was equally distributed between the right and left sides of the uterus irrespective of anterior, posterior, or fundal position and lateral when 75% or more of the placental mass was on one side of the midline. Placental location was compared in hypertensive and normotensive pregnancies.

Results

Out of the total 200 women, 152 (76%) had central and 48 (24%) had lateral placenta. Ninety-two percent of controls and 60% of cases had central placenta. Forty percent of cases and only 8% normotensive women had lateral placenta. Lateral placenta was five times more frequent in presence of PE as compared to normotensive controls. Out of 152 women with central placenta, 92 (60.5%) women were normotensive but with lateral placenta, only 8 (16.7%) had normal blood pressure. PE was present in 83% of women with lateral placenta and in only 39.47% with central placenta. This difference was statistically significant as P < 0.0001 as per Chi-square test. This reflects a significant association between lateral position of placenta and occurrence of PE. As per odds ratio (0.1304) patients without lateral placenta had 90% protection against preeclampsia.

Conclusion

Central placenta is more common than lateral placenta. Lateral placenta is seen five times more frequently among hypertensive women and this difference is statistically significant. The absence of lateral placenta provides 90% protection against PE but the severity of PE was not affected by placental location..

A mathematical model of vascular and hemodynamics changes in early and late forms of preeclampsia

Preeclampsia-eclampsia syndrome is a leading cause of maternal mortality. The precise etiology of preeclampsia is still not well-defined and different forms exist, including early and late forms or preeclampsia, which may arise via distinctly different mechanisms. Low-dose aspirin administered at the end of the first trimester in women identified as high risk has been shown to reduce the incidence of early, but not late, preeclampsia; however, current risk factors show only fair predictive capability. There is a pressing need to develop accurate descriptions for the different forms of preeclampsia. This paper presents 1D fluid, solid, growth, and remodeling models for pregnancies complicated with early and late forms of preeclampsia. Simulations affirm a broad set of literature results that early forms of preeclampsia are characterized by elevated uterine artery pulsatility index (UA-PI) and total peripheral resistance (TPR) and lower cardiac output (CO), with modestly increased mean arterial blood pressure (MAP) in the first half of pregnancy, with elevation of TPR and MAP beginning at 20 weeks. Conversely, late forms of preeclampsia are characterized by only slightly elevated UA-PI and normal pre-term TPR, and slightly elevated MAP and CO throughout pregnancy, with increased TPR and MAP beginning after 34 weeks. Results suggest that preexisting arterial stiffness may be elevated in women that develop both early forms and late forms of preeclampsia; however, data that verify these results are lacking in the literature. Pulse wave velocity increases in early- and late-preeclampsia, coincident with increases in blood pressure; however, these increases are mainly due to the strain-stiffening response of larger arteries, rather than arterial remodeling-derived changes in material properties. These simulations affirm that early forms of preeclampsia may be associated with abnormal placentation, whereas late forms may be more closely associated with preexisting maternal cardiovascular factors; simulations also highlight several critical gaps in available data.

Meta-analysis to Assess the Association of Lateral Location of Placenta on Ultrasound with Preeclampsia

Introduction

Several studies have shown association between lateral placenta on ultrasound and preeclampsia (PE).This meta-analysis aims to review majority of the articles published between 1990 and 2020 and analyze the data extracted from them to find whether such an association really exists.

Objective

To conduct a meta-analysis to determine the degree of the association of lateral placenta on ultrasound with preeclampsia.

Methods

We searched electronic databases keeping filters for human studies and published in the English language, between the year 1990 and 2020. Studies were reviewed by reviewers and studies which were analytical in nature, having focused research question and where odds ratio could be derived were identified, and included in the metanalysis.

Result

Out of 16 included studies, 15 studies showed positive association (OR > 1) out of which 13 were statistically significant and only one study showed negative association. Eight studies showed extremely significant statistical positive association. The meta-analysis points toward positive association with OR 3.48 and Mantel-Haenszel Chi square 325.82 with relatively narrow 95% confidence interval around OR as 3.03-3.99 which clearly indicates a positive association between laterally placed placenta and preeclampsia. The findings of the individual studies in terms of OR and 95% confidence interval were plotted as individual line for each study, one aggregate estimate with summary OR and its 95% confidence interval was plotted on the Forest Plot.

Conclusion

The Forest plot revealed association between lateral placenta on ultrasound and preeclampsia (PE).Hence it can be concluded that there is an association between lateral placenta on ultrasound and preeclampsia.

Utilization of Uterine and Umbilical Artery Doppler in the Second and Third Trimesters to Predict Adverse Pregnancy Outcomes: A Nigerian Experience

Objective: To assess the utility of uterine and umbilical artery Doppler in the second and third-trimester in predicting adverse pregnancy outcomes.

Methodology: In a prospective longitudinal study, the demographic, clinical, Doppler ultrasound parameters of the uterine and umbilical arteries of 84 consecutive women attending the antenatal clinic at 22–24 weeks and 116 women at 30–34 weeks gestation and pregnancy outcomes were documented and analyzed.

Results: Pregnant women with adverse pregnancy outcomes had significantly higher second-trimester mean uterine systolic/diastolic (S/D) ratio (p = 0.001), pulsatility index (PI; p = 0.003), umbilical artery S/D (p = 0.016), and resistivity index (RI; p = 0.041) as well as higher third-trimester uterine S/D and PI. While pregnancies with adverse fetal outcomes showed significantly higher uterine artery S/D and PI at the second trimester, third-trimester uterine showed higher S/D, RI, and PI and umbilical artery PI than in women with normal fetal outcomes. The combination of uterine PI and early diastolic notch were predictors of maternal outcomes and correctly predicted 73% (p < 0.001) in the second trimester. By the third trimester, the uterine PI alone was the best predictor and accurately predicted about 62% of maternal outcomes (p = 0.028). In addition, the second-trimester uterine S/D and early diastolic notch and uterine PI in the third trimester correctly predicted 79% and 78% of fetal outcomes, respectively.

Conclusion: Among unselected pregnant women population, the second-trimester Doppler parameters are better predictors of maternal adverse pregnancy outcomes, while adverse fetal outcome prediction by uterine and umbilical Doppler at the second- and the third-trimester parameters are comparable.

Lateral placentation and adverse perinatal outcomes

Lateral placentation may compromise placental perfusion, and we aimed to assess whether it impacts pregnancy outcomes. This single-center retrospective study included 1203 singleton pregnancies, categorized into two groups according to placental location. Women with lateral placenta had significantly higher risk of preterm birth <37 weeks (aOR 2.99) and <34 weeks (aOR 3.92), and gestational diabetes (aOR 2.72), compared to women with central placenta. Mean birth weight and small for gestational age (SGA) rates were similar between groups. Our findings suggest that lateral placenta may be associated with increased risk for preterm birth but not for SGA.

Preeclampsia – Prediction and Monitoring Factors

Preeclampsia is one of the leading causes of maternal and perinatal morbidity and mortality, usually characterized by hypertension and proteinuria. Despite high incidence of preeclampsia the pathophysiological basis of preeclampsia is still not clear and there are a number of mechanisms and signaling pathways that intertwine. It is very important to develop specific and reliable predictive algorithms in order to enable early initiation of therapy due to facts that incidence of preeclampsia has upward trend and that cause adverse maternal and fetal outcome. Some of the most commonly used methods for prediction of preeclampsia include uterine artery Doppler velocimetry, determination of some microRNA, such as miR-210, and assessment of various pro-angiogenic and anti-angiogenic factors from blood. Angiogenic factors that possibly have most important role in pathogenesis of preeclampsia are vascular endothelial growth factor (VEGF) and placental growth factor (PlGF), which promote angiogenesis, and soluble fms-like tyrosine kinase-1 (sFlt1) and soluble form of endoglin (s-Eng), which exhibit anti-angiogenic properties. Aggravating circumstance is that preeclampsia has heterogeneous origin, and due to this fact, the value of individual markers can vary significantly. There is a constant tendency for creating comprehensive algorithm for prediction of preeclampsia which would be sufficiently specific and sensitive, and in the same time cheap and available. In that sense, new clinical studies are needed to show the most effective combination of parameters in the predeclampsia prediction.

Placental Location and the Development of Hypertensive Disorders of Pregnancy

OBJECTIVES

Abnormal placentation is an important factor in the pathogenesis of preeclampsia. As a result of diminished blood flow, the incidence of preeclampsia might be higher in patients with laterally located placentas compared to patients with centrally located placentas. The objective of this study was to evaluate the relationship between placental location and the development of hypertensive disorders of pregnancy.

METHODS

Patients with singleton pregnancies who were seen in our ultrasound unit and delivered at our institution from October 2014 to April 2015 were included. The incidence of hypertensive disorders was compared in those with a lateral placental location and those with centrally located placentas (placental locations other than lateral). Baseline characteristics and pregnancy outcomes were compared between groups. The χ² test, Fisher exact test, Mann-Whitney U test, and t test were used when appropriate. P < .05 was considered significant.

RESULTS

We included 464 patients; 411 (88.57%) had centrally located placentas, and 53 (11.42%) had laterally located placentas. The incidence of hypertensive disorders of pregnancy was similar between groups (21% versus 19%; P = .71). Gestational age at delivery (P = .73), and small for gestational age (P = .96) were also similar between our study groups.

CONCLUSIONS

In our study, there was no difference in the rate of hypertensive disorders of pregnancy between patients with central and laterally located placentas.

Pathophysiology of placental-derived fetal growth restriction

Placental-related fetal growth restriction arises primarily due to deficient remodeling of the uterine spiral arteries supplying the placenta during early pregnancy. The resultant malperfusion induces cell stress within the placental tissues, leading to selective suppression of protein synthesis and reduced cell proliferation. These effects are compounded in more severe cases by increased infarction and fibrin deposition. Consequently, there is a reduction in villous volume and surface area for maternal-fetal exchange. Extensive dysregulation of imprinted and nonimprinted gene expression occurs, affecting placental transport, endocrine, metabolic, and immune functions. Secondary changes involving dedifferentiation of smooth muscle cells surrounding the fetal arteries within placental stem villi correlate with absent or reversed end-diastolic umbilical artery blood flow, and with a reduction in birthweight. Many of the morphological changes, principally the intraplacental vascular lesions, can be imaged using ultrasound or magnetic resonance imaging scanning, enabling their development and progression to be followed in vivo. The changes are more severe in cases of growth restriction associated with preeclampsia compared to those with growth restriction alone, consistent with the greater degree of maternal vasculopathy reported in the former and more extensive macroscopic placental damage including infarcts, extensive fibrin deposition and microscopic villous developmental defects, atherosis of the spiral arteries, and noninfectious villitis. The higher level of stress may activate proinflammatory and apoptotic pathways within the syncytiotrophoblast, releasing factors that cause the maternal endothelial cell activation that distinguishes between the 2 conditions. Congenital anomalies of the umbilical cord and placental shape are the only placental-related conditions that are not associated with maldevelopment of the uteroplacental circulation, and their impact on fetal growth is limited.

Uterine artery Doppler velocimetry in hypertensive disorder of pregnancy in Nigeria

Aim of the study

To evaluate the value of uterine artery Doppler indices and waveform pattern in predicting fetuses at risk for intrauterine growth restriction in hypertensive disorders of pregnancy.

Materials and methods

This was a prospective cross-sectional study including 80 pregnant subjects with hypertensive disorders of pregnancy and two control groups. Uterine artery Doppler sonography was performed in all study participants. Uterine artery Doppler indices across the groups were compared using the analysis of variance (ANOVA) while the presence of prediastolic notch was analyzed with the Chi Square test.

Results

For the hypertensive disorders of pregnancy group, resistivity index > 0.66 had a sensitivity of 50.0%, specificity of 69.1% and a positive predictive value of 22.2% for predicting intrauterine growth restriction. The odds ratio was 2.2 with a 95% confidence interval of 0.6–7.8. The presence of prediastolic notching had a sensitivity of 100.0%, specificity of 96.0% and a positive predictive value of 80.0% for predicting intrauterine growth restriction. The odds ratio was 22.7 with a 95% confidence interval of 7.5–68.5.

Conclusion

Uterine artery Doppler sonography is useful for predicting fetuses at risk for intrauterine growth restriction in hypertensive disorder of pregnancy. Prediastolic notching is more sensitive and more specific than uterine artery resistivity index in predicting fetuses at risk of intrauterine growth restriction in established hypertensive disorder of pregnancy.

Fetal growth restriction: current knowledge

BACKGROUND

Fetal growth restriction (FGR) is a condition that affects 5-10% of pregnancies and is the second most common cause of perinatal mortality. This review presents the most recent knowledge on FGR and focuses on the etiology, classification, prediction, diagnosis, and management of the condition, as well as on its neurological complications.

METHODS

The Pubmed, SCOPUS, and Embase databases were searched using the term "fetal growth restriction".

RESULTS

Fetal growth restriction (FGR) may be classified as early or late depending on the time of diagnosis. Early FGR (<32 weeks) is associated with substantial alterations in placental implantation with elevated hypoxia, which requires cardiovascular adaptation. Perinatal morbidity and mortality rates are high. Late FGR (≥32 weeks) presents with slight deficiencies in placentation, which leads to mild hypoxia and requires little cardiovascular adaptation. Perinatal morbidity and mortality rates are lower. The diagnosis of FGR may be clinical; however, an arterial and venous Doppler ultrasound examination is essential for diagnosis and follow-up. There are currently no treatments to control FGR; the time at which pregnancy is interrupted is of vital importance for protecting both the mother and fetus.

CONCLUSION

Early diagnosis of FGR is very important, because it enables the identification of the etiology of the condition and adequate monitoring of the fetal status, thereby minimizing risks of premature birth and intrauterine hypoxia.

Correlation between maternal serum-amniotic fluid anti-angiogenic factors and uterine artery Doppler indices

PURPOSE

Elevated sFlt-1 and sEng is usually a clue for impending preeclampsia and intrauterine growth restriction. Likewise, uterine artery Doppler ultrasound is being investigated for prediction of similar conditions. In this study, we aimed to explore the possible relations of these two proteins in different body compartments with uterine artery Doppler indices (UtAD) in a healthy second trimester obstetric population.

METHODS

Levels of sFlt-1 and sEng were measured in serum and amniotic fluid samples of 43 patients. UtAD were measured on the days of sample collections. Findings were then analyzed for possible correlation.

RESULTS

There was a positive correlation between the levels of maternal serum sFlt-1 (MSsFlt-1) and sEng levels (MSsEng) (r= 0.516, p< 0.001). The negative correlation between MSsFlt-1 and UtAD was disappeared after elimination of poor obstetric outcome pregnancies (r= -0.371, p= 0.016). No correlation was found between UtAD and studied protein levels in amniotic fluid. Mean MSsFlt-1 level was 305.2 ± 220.1 pg/ml and mean AFsFlt-1 was 48.9 ± 11.8 ng/ml. Mean MSsEng level was 4.5 ± 1.3 ng/ml, mean AFsEng level was found 0.7 ± 0.3 ng/ml. Mean values for UtAD were 1.3 ± 0.4, 0.6 ± 0.1 and 3.5 ± 1.3 for PI, RI, and S/D, respectively.

CONCLUSION

In normal second trimester pregnancies, there is a positive correlation between serum levels of sFlt-1 and sEng levels. Amniotic fluid levels of sEng and sFlt-1 are not correlated with UtAD in uncomplicated pregnancies.

Diminishing Exposure to Doppler Ultrasound

Diagnostic ultrasound has an unblemished record for safety. The introduction of pulsed Doppler may involve higher intensities exceeding 1 W/cm2 (SPTA). These intensities must cause concern for fetal exposure, and the FDA has introduced strict guidelines to limit such exposure. Presented here are practical ways in which sonography can minimize exposure. These include the use of Doppler only when clinically indicated or part of an approved research protocol, knowledge of the emitted intensity, and how to attenuate this to prudent levels. It is desirable to use sensitive equipment and increase the TGC before increasing power. Such prudent use will allow ultrasound to be used in these new applications without hazard.

Reference range for uterine artery Doppler pulsatility index using transvaginal ultrasound at 20-24w6d of gestation in a low-risk Brazilian population

OBJECTIVE

To establish reference range for uterine artery (UtA) Doppler pulsatility index (PI) using transvaginal ultrasound at 20-24w6d of gestation in a Brazilian population.

MATERIAL AND METHODS

A retrospective cross-sectional study in 847 low-risk pregnant women undergoing routine second trimester ultrasound examination was conducted from February 2012 through March 2015. The mean UtA PI was calculated using color Doppler ultrasound with UtA gated at the level of the internal os. Mean±standard deviation and ranges for UtA Doppler PI in relation to gestational age (GA) are reported. Polynomial regression was used to obtain the best fit using mean UtA Doppler PI and GA (weeks) with adjustments performed using determination coefficient (R(2)). The 5(th), 50(th), and 95(th) percentiles for the mean UtA Doppler PI in relation to GA were determined.

RESULTS

The mean UtA Doppler PI ranged from 1.14 at 20 weeks to 0.95 at 24 weeks of gestation. The best-fit curve of mean UtA Doppler PI as a function of GA was a first-degree polynomial regression: mean UtA Doppler PI=1.900-0.038×GA (R(2)=0.01).

CONCLUSION

In summary, when the mean UtA PI Doppler values were measured by transvaginal ultrasound at 20-24w6d of gestation, decrease in UtA Doppler PI values with advancing GA was observed. Reference range for the mean UtA Doppler PI at 20-24w6d of gestation using the transvaginal ultrasound in a low-risk Brazilian population was established. We believe that this reference range may be of clinical value in daily obstetric practice.

Predictive accuracy of second-trimester uterine artery Doppler indices for stillbirth: a systematic review and meta-analysis

OBJECTIVE

To assess the predictive accuracy for stillbirth of second-trimester uterine artery Doppler.

METHODS

We searched MEDLINE, EMBASE and The Cochrane Library databases from inception until March 2015 without language restrictions. The included studies were those that assessed the association of abnormal uterine artery Doppler parameters and stillbirth. Two independent reviewers selected the studies, extracted data and assessed quality. Results for studies that were performed in the second trimester were pooled and summary estimates of sensitivity, specificity, likelihood ratios and their 95% confidence intervals were obtained. An overall summary of test accuracy was provided by the diagnostic odds ratio. Subgroup analysis was performed according to whether the study population was high risk or unselected.

RESULTS

Literature searches returned 338 relevant citations with 32 considered in full. Thirteen studies met our search criteria (85 845 women, 508 stillbirths) and were included in the review. Bivariate pooled estimate for sensitivity was 65% (95% CI, 38-85%) and for specificity 82% (95% CI, 72-88%). The positive likelihood ratio was 3.5 (95% CI, 2.3-5.5) and negative likelihood ratio 0.43 (95% CI, 0.22-0.85). The diagnostic odds ratio was 8.3 (95% CI, 3.0-22.4). Heterogeneity was high in the studies of high-risk women.

CONCLUSIONS

Abnormal uterine artery Doppler indices are associated with a three- to four-fold increase in the risk of stillbirth. The heterogeneity was particularly high in the high-risk group rendering it impossible to draw firm conclusions. In view of this, there is a role for individual patient data meta-analysis to define which Doppler parameter and threshold value should be measured.

Chronic hypertension and pregnancy outcomes: systematic review and meta-analysis

OBJECTIVE

To provide an accurate assessment of complications of pregnancy in women with chronic hypertension, including comparison with population pregnancy data (US) to inform pre-pregnancy and antenatal management strategies.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Embase, Medline, and Web of Science were searched without language restrictions, from first publication until June 2013; the bibliographies of relevant articles and reviews were hand searched for additional reports.

STUDY SELECTION

Studies involving pregnant women with chronic hypertension, including retrospective and prospective cohorts, population studies, and appropriate arms of randomised controlled trials, were included.

DATA EXTRACTION

Pooled incidence for each pregnancy outcome was reported and, for US studies, compared with US general population incidence from the National Vital Statistics Report (2006).

RESULTS

55 eligible studies were identified, encompassing 795,221 pregnancies. Women with chronic hypertension had high pooled incidences of superimposed pre-eclampsia (25.9%, 95% confidence interval 21.0% to 31.5 %), caesarean section (41.4%, 35.5% to 47.7%), preterm delivery <37 weeks' gestation (28.1% (22.6 to 34.4%), birth weight <2500 g (16.9%, 13.1% to 21.5%), neonatal unit admission (20.5%, 15.7% to 26.4%), and perinatal death (4.0%, 2.9% to 5.4%). However, considerable heterogeneity existed in the reported incidence of all outcomes (τ(2)=0.286-0.766), with a substantial range of incidences in individual studies around these averages; additional meta-regression did not identify any influential demographic factors. The incidences (the meta-analysis average from US studies) of adverse outcomes in women with chronic hypertension were compared with women from the US national population dataset and showed higher risks in those with chronic hypertension: relative risks were 7.7 (95% confidence interval 5.7 to 10.1) for superimposed pre-eclampsia compared with pre-eclampsia, 1.3 (1.1 to 1.5) for caesarean section, 2.7 (1.9 to 3.6) for preterm delivery <37 weeks' gestation, 2.7 (1.9 to 3.8) for birth weight <2500 g, 3.2 (2.2 to 4.4) for neonatal unit admission, and 4.2 (2.7 to 6.5) for perinatal death.

CONCLUSIONS

This systematic review, reporting meta-analysed data from studies of pregnant women with chronic hypertension, shows that adverse outcomes of pregnancy are common and emphasises a need for heightened antenatal surveillance. A consistent strategy to study women with chronic hypertension is needed, as previous study designs have been diverse. These findings should inform counselling and contribute to optimisation of maternal health, drug treatment, and pre-pregnancy management in women affected by chronic hypertension.

The utility of uterine artery Doppler velocimetry in prediction of preeclampsia in a low-risk population

OBJECTIVE

The underlying pathophysiology of preeclampsia is thought to be abnormal trophoblast invasion of the spiral arteries leading to maldevelopment of uteroplacental perfusion. We estimated whether uterine artery Doppler measurements made in the early second trimester would predict the subsequent development of preeclampsia.

METHODS

Uterine artery Doppler measurements before 21 weeks of gestation (median 16.6 weeks) were correlated with subsequent development of preeclampsia in a cohort of 2,188 low-risk nulliparous women in a randomized control trial of antioxidant supplementation for prevention of preeclampsia. Preeclampsia developed in 165 (7.5%) women.

RESULTS

Development of preeclampsia overall was associated with increased resistance index, pulsatility index, a pulsatility index or resistance index multiple of the median at or above the 75th percentile but not the presence of a notch or a bilateral notch before 21 weeks of gestation. The sensitivity was 43% (95% confidence interval [CI] 35-51) and specificity 67% (95% CI 65-69) for prediction of preeclampsia overall. The presence of a notch or bilateral notch, resistance index, and pulsatility index multiple of the median was significantly associated with early onset (before 34 weeks of gestation) compared with late onset or no preeclampsia (odds ratio [OR] 6.9, 95% CI 2.3-20.9; sensitivity 78%, 95% CI 52-94; specificity 66%, 95% CI 64-68). The presence of a notch or resistance index multiple of the median at or above the 75th percentile increased the odds of developing severe compared with mild or no preeclampsia (OR 2.2, 95% CI 1.4-3.7; sensitivity 53%, 95% CI 40-65; specificity 66%, 95% CI 64-68).

CONCLUSION

Our data show poor sensitivity of second-trimester Doppler ultrasound measurements for prediction of preeclampsia overall in a well-characterized, low-risk, nulliparous population. The technique has utility in identifying poor trophoblast invasion of spiral arteries of a magnitude that severely compromises uteroplacental blood flow and gives early-onset disease.

LEVEL OF EVIDENCE

II.

Placental laterality as a predictor for development of preeclampsia

OBJECTIVE

To find whether placental laterality as determined by ultrasound can be used as predictor for the development of preeclampsia.

METHODS

This prospective study was conducted in the Department of Obstetrics and Gynecology, Govt. Medical College, Jammu from 2006 to 2007. 150 pregnant women attending antenatal clinic both OPD and IPD at 18-24 weeks of gestation without any high risk factor were subjected to ultrasound examination, and placental location was determined. These cases were followed for the development of signs and symptoms of preeclampsia.

RESULT

Out of the total 150 women, 84 (56 %) had laterally located placenta and of them, 56 (66.6 %) developed preeclampsia, while the remaining 66 (44 %) had centrally located placenta and of them, 24 (36.3 %) developed preeclampsia. So, the overall risk of developing preeclampsia with laterally located placenta was 5.09 (odds ratio) and 95 % confidence interval (2.40-10.88). The difference was found to be statistically significant, p value (0.00002) by χ(2) test.

CONCLUSION

From the above study, we concluded that females with laterally located placenta determined by USG at 18-24 weeks of gestation have five times greater risk of developing preeclampsia.

Should bilateral uterine artery notching be used in the risk assessment for preeclampsia, small-for-gestational-age, and gestational hypertension?

OBJECTIVE

The purpose of this study was to determine the value of bilateral uterine artery notching in the second trimester in the risk assessment for preeclampsia, gestational hypertension, and small-for-gestational-age (SGA) without preeclampsia.

METHODS

This prospective cohort study included 4190 singleton pregnancies that underwent ultrasound examination between 23 and 25 weeks' gestation. The 95th percentiles of the mean pulsatility index (PI) and resistive index (RI) of both uterine arteries were calculated. Multivariable logistic regression analyses were performed to determine if bilateral uterine artery notching is an independent explanatory variable for the occurrence of preeclampsia, early-onset preeclampsia (<or=34 weeks), late-onset preeclampsia (>34 weeks), gestational hypertension, and delivery of an SGA neonate without preeclampsia, while controlling for confounding factors.

RESULTS

(1) The prevalence of preeclampsia, early-onset preeclampsia, late-onset preeclampsia, SGA, and gestational hypertension were 3.4%, 0.5%, 2.9%, 10%, and 7.9%, respectively; (2) 7.2% of the study population had bilateral uterine artery notching; and (3) bilateral uterine artery notching was an independent explanatory variable for the development of preeclampsia (odds ratio [OR], 2.1; 95% confidence interval [CI],1.28-3.36), early-onset preeclampsia (OR, 4.47; 95% CI, 1.50-13.35), and gestational hypertension (OR, 1.50; 95% CI, 1.02-2.26), but not for late-onset preeclampsia or SGA.

CONCLUSIONS

Bilateral uterine notching between 23 and 25 weeks' gestation is an independent risk factor for the development of early-onset preeclampsia and gestational hypertension. Thus, bilateral uterine artery notching should be considered in the assessment of risk for the development of these pregnancy complications.

Effect of antihypertensive therapy with alpha-methyldopa on uterine artery Doppler in pregnancies with hypertensive disorders

OBJECTIVES

Antihypertensive drugs lower blood pressure by direct vascular effects or central vasodilatory mechanisms. Their effect on uterine artery Doppler resistance indices in hypertensive disorders of pregnancy is uncertain. This study aimed to evaluate the impact of antihypertensive therapy with alpha-methyldopa on maternal uterine artery Doppler pulsatility index (PI) and resistance index (RI) in women presenting with hypertensive disorders of pregnancy.

METHODS

This was a cross-sectional study of 51 women with pre-eclampsia, 29 with gestational hypertension and 80 matched normotensive controls. Uterine artery PI and RI were measured at recruitment (between 24 and 40 weeks' gestation) and, in the hypertensive groups, 24-48 h after starting alpha-methyldopa. Differences between mild and severe, and between early- and late-onset pre-eclampsia were compared using the Mann-Whitney test. The Wilcoxon rank sum test was used to compare measurements before and after treatment.

RESULTS

Prior to treatment, uterine artery PI and RI were significantly higher in women with pre-eclampsia compared with those with gestational hypertension and controls (P < 0.0001). The median uterine artery PI multiple of the median (MoM) was significantly higher (P < 0.0001) in early-onset than in late-onset pre-eclampsia (1.83 (range, 0.88-3.65) vs. 1.19 (range, 0.91-1.72)) and in severe compared with mild disease (2.26 (range, 2.02-3.65) vs. 1.29 (range, 0.88-2.9)). Uterine artery PI- and RI-MoMs in both pre-eclampsia and gestational hypertension, before and after 34 weeks' gestation, were not affected by alpha-methyldopa treatment.

CONCLUSIONS

Antihypertensive therapy using alpha-methyldopa in women presenting with hypertensive disorders of pregnancy has no significant effect on uterine artery resistance to blood flow, suggesting that it does not impair uteroplacental circulation in these cases.

Plasma soluble vascular endothelial growth factor receptor-1 concentration is elevated prior to the clinical diagnosis of pre-eclampsia

OBJECTIVE

Accumulating evidence suggests that the balance between vascular endothelial growth factor (VEGF), placental growth factor (PIGF), and their receptors is important for effective vasculogenesis, angiogenesis, and placental development. Recently, the soluble form of VEGFR-1 (sVEGFR-1), an antagonist to VEGF and PIGF, has been implicated in the pathophysiology of pre-eclampsia. Plasma sVEGFR-1 concentration is elevated in pre-eclampsia at the time of clinical diagnosis and correlates with the severity of the disease. The purpose of this study was to determine whether the concentrations of sVEGFR-1 in plasma of pre-eclamptic patients change prior to the clinical manifestations of the disease.

METHODS

A longitudinal case-control study was conducted in normal pregnant women (n = 44) and patients with pre-eclampsia (n = 44). Blood sampling was performed at six intervals: (1) 7-16 weeks; (2) 16-24 weeks; (3) 24-28 weeks; (4)28-32 weeks; (5) 32-36 weeks; and (6) more than 37 weeks of gestation. To examine the relationship between plasmasVEGFR-1 concentration and interval to clinical diagnosis of pre-eclampsia, plasma samples of pre-eclamptic patients at different gestational ages were stratified according to the interval from blood sampling to clinical development of the disease into five groups: (1) at clinical manifestation; (2) 2-5 weeks; (3) 6-10 weeks; (4) 11-16 weeks; and (5) 17-25 weeks before clinical manifestations. Plasma concentrations of sVEGFR-1 were determined by enzyme-linked immunoassay. Parametric statistics and repeated measure procedures were used for the analysis.

RESULTS

The mean plasma sVEGFR-1 concentration in pre-eclamptic patients before the clinical manifestation of the disease was significantly higher than in normal pregnant women at 24-28, 28-32, and 32-37 weeks of gestation (p = 0.02,p < 0.001, and p < 0.001, respectively). In contrast, no significant differences in the mean plasma sVEGFR-1 concentration between patients with pre-eclampsia and normal pregnant women were observed both at 7-16 weeks and 16-24 weeks of gestation (p= 0.1 and p= 0.9). Similarly, the mean plasma sVEGFR-1 concentration was significantly higher in pre-eclamptic patients than in normal pregnant women at clinical manifestation, at 2-5 weeks (mean 3.8 weeks), and at 6-10 weeks (mean 8.2 weeks) prior to the development of clinical pre-eclampsia (p < 0.001, p < 0.001, and p = 0.002,respectively). Among patients with early-onset pre-eclampsia (defined as gestational age of 34 weeks or less), the mean plasma sVEGFR-1 concentration was significantly higher in pre-eclampsia (before clinical diagnosis) than in normal pregnant women at 24-28 (mean 26.4) weeks of gestation (p = 0.008). In contrast, among patients with the late-onset disease(defined as gestational age of more than 34 weeks), plasma sVEGFR-1 concentration in pre-clinical pre-eclampsia was significantly higher than in normal pregnant women at 28-32 (mean 30.2) weeks of gestation (p < 0.001).

CONCLUSIONS

Plasma sVEGFR-1 concentration is elevated in pre-eclampsia prior to the clinical diagnosis of the disease. This elevation began 6-10 weeks prior to the clinical manifestations, and the increase was more pronounced at 2-5 weeks before the diagnosis, as well as at clinical presentation. Furthermore, in early-onset pre-eclampsia, plasma concentration ofsVEGFR-1 is elevated earlier than the late-onset disease.

Evaluation of the utero-placental circulation by three-dimensional Doppler ultrasound in the second trimester of normal pregnancy

OBJECTIVE

To define normative data with three-dimensional (3D) Doppler ultrasound in the second trimester spiral arteries and placental volume blood flow.

METHODS

An entry criterion was a documented singleton pregnancy at 14-25 weeks with normal outcome. Each patient had a 3D power Doppler exam. Automatic volume acquisition of the placental and spiral arteries blood flow was obtained. We calculated vascularization index (VI), flow index (FI) and vascularization flow index (VFI). The patients were further divided into subgroups based on two gestational week intervals. The outcome measure was normal pregnancy outcome.

RESULTS

One hundred ninety-nine patients were included in this study. Placental and spiral arteries vascular indices slowly increased indicating progressive development of vascular network and increase in the volume blood flow. The range for placental VI was 11.43-14.63, FI was 37.44-40 and VFI was 4.77-6.06. The range for spiral arteries VI was 19-20.91, FI was 39.66-41.1 and VFI was 8.49-8.92. The mean gestational age at delivery was 38.18 weeks.

CONCLUSION

We defined normal 3D power Doppler vascular indices in pregnancies between 14 and 25 weeks of singleton gestation. The study indicated that placental and spiral arteries volume blood flow increased with the advancement of gestational age.

Ultrasound of the placenta: a systematic approach. Part II: functional assessment (Doppler)

Doppler velocimetry is the ideal clinical tool to assess placental performance in high-risk pregnancies. It also has value in predicting later complications and outcome in pregnancies which appear uncomplicated. All three circulations (fetal, placental and maternal) may be interrogated by Doppler technology. In the following review, we present basic physics aspects of Doppler and discuss mainly Doppler investigation of the fetal-placental circulation (umbilical artery, intraplacental circulation) as well as the uterine arteries. The assessment of umbilical blood flow provides information on blood perfusion of the fetal-placental unit. The diastolic blood flow velocity component in umbilical artery increases with advancing gestation. In pregnancies complicated by placental dysfunction, there may be a reduction in the number of functional villi and/or small blood vessels with, as a result, increased impedance, reflected, mainly, by a decrease in end-diastolic velocity. When the resistance increases even more, there is no diastolic forward velocity (absent end-diastolic velocity). Further increase in the resistance causes reversed end-diastolic velocity, which is considered a late step in the cascade of events leading to intrauterine fetal demise. Doppler assessment of the umbilical arteries was found to improve outcome of high-risk pregnancies, and reduce hospital admissions. On the contrary, routine Doppler ultrasound in low risk or unselected populations does not seem to confer benefit on mother or newborn. Uterine artery Doppler is a useful test in predicting pregnancies at high risk of developing complications related to uteroplacental insufficiency. It identifies women who may benefit from increased antenatal surveillance or prophylactic therapy. Three-dimensional power Doppler sonography can provide new insights into placental pathophysiology.

The maternal plasma soluble vascular endothelial growth factor receptor-1 concentration is elevated in SGA and the magnitude of the increase relates to Doppler abnormalities in the maternal and fetal circulation

OBJECTIVES

The soluble form of vascular endothelial growth factor receptor-1 (sVEGFR-1), an antagonist to vascular endothelial growth factor and placental growth factor, has been implicated in the pathophysiology of preeclampsia. Preeclampsia and pregnancy complicated with small for gestational age (SGA) fetuses share some pathophysiologic derangements, such as failure of physiologic transformation of the spiral arteries, endothelial cell dysfunction, and leukocyte activation. The objectives of this study were to: (1) determine whether plasma concentrations of sVEGFR-1 in mothers with SGA fetuses without preeclampsia at the time of diagnosis are different from those in patients with preeclampsia or normal pregnant women, and (2) examine the relationship between plasma concentrations of sVEGFR-1 and Doppler velocimetry in uterine and umbilical arteries in patients with preeclampsia and those with SGA.

STUDY DESIGN

A cross-sectional study was conducted to determine the concentrations of the soluble form of VEGFR-1 in plasma obtained from normal pregnant women (n = 135), women with SGA fetuses (n = 53), and patients with preeclampsia (n = 112). Patients with SGA fetuses and those with preeclampsia were sub-classified according to the results of uterine and umbilical artery Doppler velocimetry examinations. Plasma concentrations of sVEGFR-1 were determined by an ELISA. Since these concentrations change with gestational age, differences among various subgroups were statistically estimated with the delta value, defined as the difference between the observed and expected plasma sVEGFR-1 concentration. The expected values were derived from regression analysis of plasma sVEGFR-1 concentrations in normal pregnancy. Regression analysis and univariate and multivariate analysis were employed.

RESULTS

(1) Mothers with SGA fetuses had a mean plasma concentration of sVEGFR-1 higher than normal pregnant women (p < 0.001), but lower than patients with preeclampsia (p < 0.001). (2) Among patients with SGA fetuses, only those with abnormal uterine artery Doppler velocimetry had a mean plasma sVEGFR-1 concentration significantly higher than normal pregnant women (p < 0.001). (3) Among mothers with SGA fetuses in whom Doppler velocimetry was performed (n = 41), those with abnormalities in both the uterine and umbilical artery velocimetry had the highest mean delta of sVEGFR-1 plasma concentration (mean +/- standard deviation (SD): 0.69 +/- 0.29). Conversely, patients who had normal Doppler velocimetry in both uterine and umbilical arteries had the lowest mean delta (mean +/- SD: 0.09 +/- 0.29) of sVEGFR-1 plasma concentrations (ANOVA; p < 0.001). (4) Among patients with preeclampsia in whom Doppler velocimetry was performed (n = 69), those with abnormalities in both the uterine and umbilical artery velocimetry had the highest mean delta sVEGFR-1 plasma concentration (mean +/- SD: 1.01 +/- 0.22) among all groups classified (ANOVA; p < 0.001). (5) Among patients with SGA and those with preeclampsia, there was a relationship (Chi-square for trend p < 0.001 for both) between the severity of Doppler velocimetry abnormalities and the proportion of patients who had high delta sVEGFR-1 plasma concentrations (defined as a concentration two standard deviations (2SD) above the mean delta of normal pregnant women). (6) Multiple regression analysis suggested that the diagnostic category (e.g., SGA or preeclampsia), Doppler abnormalities, and gestational age at blood sampling were associated with an increase in plasma sVEGFR-1 concentrations (p < 0.001).

CONCLUSIONS

These observations provide support for the participation of the soluble receptor of vascular endothelial growth factor in the pathophysiology of SGA with abnormal uterine artery Doppler velocimetry and preeclampsia. An excess of sVEGFR-1 is released into the maternal circulation of patients with preeclampsia and those with SGA fetuses, as abnormalities of impedance to blood flow involve uterine and umbilical circulation.

Maternal total vascular resistance and concentric geometry: a key to identify uncomplicated gestational hypertension

OBJECTIVE

To evaluate the prognostic impact of elevated total vascular resistance (TVR) on the outcome of pregnancy in early mild gestational hypertension (EMGH).

DESIGN

Prospective observational study.

SETTING

Data collected from women with EMGH referred to the obstetrics outpatient clinic of Tor Vergata University from June 2003 to June 2005.

POPULATION

A total of 268 women with EMGH (systolic and diastolic blood pressure [BP] 140-150 mmHg and 90-99 mmHg, respectively, without significant proteinuria).

METHODS

Women had a maternal echocardiographic examination and BP examination within 24 hours of diagnosis. From this, the TVR was calculated and the geometric pattern of the left ventricle assessed.

MAIN OUTCOME MEASURES

Fetal/maternal adverse outcomes (pre-eclampsia, preterm delivery, placental abruption, other maternal medical problems, fetal distress, neonatal low birthweight, admittance to neonatal intensive care unit and perinatal death).

RESULTS

Ninety-two out of the 268 pregnancies showed adverse outcomes (34.3%). The best independent predictor for the composite of maternal and fetal complications was TVR (OR 64.4, 95% CI 25.9-160.1). The cutoff value was 1340 dyn seconds/cm(5) with a sensitivity and a specificity of 90 and 91%, respectively. Concentric geometry of the left ventricle was also an independent predictor (OR 4.72, 95% CI 1.85-12.04).

CONCLUSIONS

Echocardiography could help in identifying women with EMGH who subsequently develop maternal and fetal complications, allowing a classification in high-risk (TVR > 1340 dyn seconds/cm(5), concentric geometry of the left ventricle) and low-risk women (TVR < 1340 dyn seconds/cm(5), nonconcentric geometry of the left ventricle) for adverse outcomes of pregnancy.

Qual o melhor período para a realização do doppler das artérias uterinas na predição de complicações da gestação?

OBJETIVO: Avaliar, prospectivamente, qual o melhor período para a realização do Doppler das artérias uterinas na predição de complicações da gestação. MATERIAIS E MÉTODOS: Foi conduzido estudo prospectivo em 45 pacientes primigestas, sem história de doenças crônicas. O Doppler das artérias uterinas foi realizado entre 18-20, 24-26, 28-30 e 34-36 semanas, com determinação do índice de resistência, índice de pulsatilidade, relação A/B e a presença ou ausência de incisura na onda de velocidade de fluxo, assim como o resultado da gestação. RESULTADOS: Os índices Doppler apresentaram decréscimo com o decorrer da gestação, mais pronunciado nas gestações normais quando estas foram comparadas com aquelas que tiveram complicações, de maneira mais acentuada no exame realizado entre 24-26 semanas. A melhor relação entre sensibilidade e especificidade para a detecção de complicações durante a gestação foi obtida no exame realizado entre 24-26 semanas. CONCLUSÃO: O melhor período para a realização do Doppler das artérias uterinas na predição de complicações da gestação é o intervalo entre 24-26 semanas.

Normal and abnormal transformation of the spiral arteries during pregnancy

This article reviews the anatomy and physiology of the uterine circulation, with emphasis on the remodeling of spiral arteries during normal pregnancy, and the timing and anatomical pathways of trophoblast invasion of the spiral arteries. We review the definitions of the placental bed and basal plate of the placenta, their relevance to the study of the physiologic transformation of the spiral arteries, as well as the methods to obtain and examine placental bed biopsy specimens. We also examine the role of the extravillous trophoblast in normal and abnormal pregnancies, and the criteria used to diagnose failure of physiologic transformation of the spiral arteries. Finally, we comment on the use of uterine artery Doppler velocimetry as a surrogate marker of chronic uteroplacental ischemia.

The relation of increased uterine artery blood flow resistance and impaired trophoblast invasion in pre-eclamptic pregnancies

OBJECTIVE

To assess the association between histopathologically confirmed vascular abnormalities developed during pre-eclampsia and abnormal arterial blood flows recorded during Doppler sonographies.

MATERIALS AND METHODS

From pregnant women who attended our clinic between 01/03/2002 and 01/07/2002, a detailed medical history was obtained and routine biochemical blood tests, fetal ultrasonography and UA Doppler scans were performed. In addition, from pre-eclamptic and normal pregnant women who underwent cesarean sections, placental bed biopsies were taken. Thirty two pre-eclamptic [12 mild, 20 severe cases according to American College of Obstetricians and Gynecologists (ACOG) criteria] cases and as a control group 20 normal pregnancies were included in the study. In our study trophoblast invasion into decidual spiral arteries was observed in 75% of mild (9/12), and 55% of severe (11/20) pre-eclampsias. In the control group all the cases demonstrated trophoblast invasion in decidual spiral arteries. Trophoblast invasion in myometrial spiral arteries was noted in 50% (6/12) of mild and 25% (5/20) of severe pre-eclamptic pregnancies. It was seen in 16 cases out of 20 (80%) pregnancies. In the control group, decidual spiral artery invasion manifests significant differences (P<0.01) among groups studied. Invasion in decidual spiral arteries was seen in all normal pregnancies of the control group. There is not any significant difference between mild and severely pre-eclamptic groups (P>0.05).

CONCLUSION

Doppler ultrasonography is not only a non-invasive method for evaluating fetal status in pre-eclamptic pregnancies, but it also correlates with partial trophoblastic invasion in spiral arteries, which contributes to the pathophysiologic mechanisms involved in pre-eclampsia.

Effect of maternal age on uterine flow impedance

PURPOSE

This study was conducted to determine possible maternal age-related changes in uterine artery impedance in normal late pregnancy.

PATIENTS AND METHODS

In a cross-sectional design study, Doppler velocimetry of the uterine vessels was performed in 884 pregnant women with normal, late, singleton pregnancies. We hypothesized that maternal age is associated with changes in uterine blood flow Doppler parameters. We tested for univariate associations and for an adjusted relationship between these factors using a multivariate model to control for confounders.

RESULTS

We found a statistically significant, nonlinear relationship between mean uterine artery impedance (pulsatility index) and maternal age, with an increase of the pulsatility index in women above the age of 35. This association continued to be significant even when adjusted for gestational age and parity as confounders.

CONCLUSIONS

In normal pregnancy, an increase in uterine artery impedance was noted in women above the age of 35. This finding may be related to the physiologic process of aging and may partly explain why pregnancies in older women are associated with diverse complications more often than those in younger women.

Serum leptin levels and uterine Doppler flow velocimetry at 20 weeks' gestation as markers for the development of pre-eclampsia

Altered Doppler flow velocimetry of the uterine arteries during the second trimester is correlated with the risk of developing pre-eclampsia. Serum levels of leptin, a protein regulating body weight and secreted by the placenta, are higher in women with severe pre-eclampsia. We investigated whether alterations of uterine arteries' Doppler flow velocimetry during the early second-trimester scan were accompanied by changes in leptin levels, and whether these changes might be an early risk factor for pre-eclampsia. We retrospectively selected 50 women with altered uterine artery velocimetry at the second-trimester scan who subsequently developed pre-eclampsia (group A) and 100 women who did not develop pre-eclampsia, divided into two groups: 50 women with normal velocimetry at the second-trimester scan (group B) and 50 women with altered velocimetry at the second-trimester scan (group C). Serum leptin levels during the second and third trimesters and bilateral uterine artery resistance index during the second trimester were evaluated. No differences were observed in serum leptin levels in the second trimester among the three groups. During the third trimester, women in group A showed significantly higher serum leptin levels in comparison with women in groups B and C (p < 0.01). Serum leptin levels do not seem to be a useful early marker for the development of pre-eclampsia in the presence of altered uterine blood flow, and may be a late compensatory mechanism or reflect a generalized response of the trophoblast to hypoxic stimuli.

The value of uterine artery Doppler ultrasound in the prediction of severe complications in a risk population

AIM

The aim of this prospective study was to assess the role of uterine artery color Doppler waveform analysis in the prediction of adverse pregnancy outcome such as preeclampsia, intrauterine growth retardation, placental abruption or a combination of outcome parameters in risk pregnancies (n=52).

METHODS

Various uterine artery Doppler ultrasound parameters (resistance index (RI)>0.58, RI>0.7 and uni/bilateral or bilateral notching) were tested. The mean time of delivery was 37+1 weeks' gestation. Six newborns (12%) were delivered before 34 weeks of gestation. The mean birth weight was 2,910 g. Dystrophic fetuses (<10% percentile) were registered in 7 cases (13%). In 11 of the 52 women (21%) a cesarean section was performed because of abnormal fetal heart recording.

RESULTS

Preeclampsia was diagnosed in 4 cases (8%). In 4 cases (8%) an intrauterine fetal death was diagnosed. Placental abruption did not occur. The sensitivity of notching for the prediction of preeclampsia and for the prediction of a severe pregnancy complication was 75 and 69% with relative risks of 2.7 and 2.0. The sensitivity of notching in the uterine arteries for developing an intrauterine growth retardation (IUGR) was 71% with a relative risk of 2.2. The sensitivity of RI>0.58 in the uterine arteries for developing an IUGR was 67% with a relative risk of 5.4. The sensitivity of RI>0.58 for the prediction of preeclampsia, of intrauterine death and for the prediction of a severe pregnancy complication was 50, 75 and 80% with relative risks of 2.7, 8.1 and 10.9 respectively.

CONCLUSION

The results of this study suggest that Doppler ultrasound of the uterine artery in the second trimester of gestation is a useful method to predict abnormal outcomes in risk pregnancies, with high negative predictive values.

End tidal carbon monoxide levels are lower in women with gestational hypertension and pre-eclampsia

BACKGROUND

The possible role of heme oxygenase and its byproduct carbon monoxide (CO) in the regulation of blood pressure is under investigation. The aim of this study was to compare end tidal breath CO (ETCO) levels in women with gestational hypertension (GH) or pre-eclampsia to the levels in healthy pregnant and nonpregnant women.

MATERIALS AND METHODS

We prospectively performed ETCO measurements corrected for ambient CO (ETCOc) in two medical centers (Stanford, CA and Cleveland, OH). A Natus CO-Stat End Tidal Breath Analyzer (Natus Medical Inc., San Carlos, CA) was used. The study group included a convenience sample of 31 women with GH/pre-eclampsia (PE). Control groups included 46 nonpregnant healthy women, 44 first-trimester and 48 third-trimester pregnant healthy women.

RESULTS

Mean+/-SD ETCOc measurements were significantly lower in the GH/PE group compared to first-trimester (p=0.004) and third-trimester (p=0.001) normotensive pregnant and nonpregnant women (p=0.002) (1.36+/-0.30 vs 1.76+/-0.47, 1.72+/-0.42 and 1.78+/-0.54 ppm, respectively). The ETCOc values were < or =1.6 ppm in 89% of GH/PE women compared with, respectively, only 45, 54, and 46% of nonpregnant, first- and third-trimester normotensive pregnant women (p<0.05). ETCO measurements were not influenced by maternal age, parity, ethnicity, body mass index, gestational age or presence of household smokers. In the two centers, the controls had a similar mean ETCOc and the differences found remained significant when results for each center were analyzed separately.

CONCLUSIONS

ETCOc levels were found to be significantly lower in women with GH/PE. Further investigation is required to determine if the lower CO levels reflect a deficient compensatory response to the increase in blood pressure or whether these are primary changes of significance to our understanding of the pathogenesis of GH/PE.

Maternal and fetal artery Doppler findings in women with chronic hypertension who subsequently develop superimposed pre-eclampsia

OBJECTIVE

To carry out a prospective study of Doppler velocimetry of the fetomaternal circulation in women with chronic hypertension, to evaluate whether the subsequent development of superimposed pre-eclampsia can be predicted.

STUDY DESIGN

Serial Doppler studies of the maternal uterine and renal arteries, and fetal middle cerebral and umbilical arteries, were performed at 16-20 and at 28-32 weeks' gestation in 56 women with chronic hypertension. Pulsatility indices were compared using the Wilcoxon rank sum method. A p value of < 0.05 was considered significant.

RESULTS

Uterine artery impedance was significantly elevated as early as 16-20 and at 28-32 weeks' gestation, while the cerebroplacental ratio was lower at 28-32 weeks' gestation, in the 14 women who developed superimposed pre-eclampsia. The maternal renal artery impedance remained constant throughout gestation, regardless of the development of pre-eclampsia.

CONCLUSIONS

Uterine artery Doppler velocimetry at 16-20 and at 28-32 weeks' gestation showing increased impedance is predictive for the development of superimposed pre-eclampsia in women with chronic hypertension. The cerebroplacental ratio suggested early fetal brain sparing at 28-32 weeks' gestation in these women.

Uterine artery blood flow velocity waveforms during uterine contractions

OBJECTIVE

No quantitative or qualitative Doppler velocimetry classification of vascular flow resistance covering all stages of forward and reversed flows exists. The objective of this study was to characterize uterine artery (UtA) flow velocity waveforms (FVWs) obtained during an oxytocin challenge test (OCT) and compare them to FVWs in spontaneous normal labor.

METHODS

Uterine artery Doppler velocimetry was performed during and between uterine contractions in 61 high-risk pregnancies subjected to an OCT and in 20 normal pregnancies undergoing spontaneous labor. FVWs were classified relative to the presence of forward/absent/reversed flow during systole and diastole, and the time-averaged flow velocity over the heart cycle.

RESULTS

Eleven different FVW classes were identified. No relationship between FVWs recorded during uterine inertia and contractions was found (P >/= 0.2). In both groups, only forward FVWs were recorded between contractions, whereas during contractions flow reversal was more common in the OCT group (P </= 0.002). In cases of predominantly reversed flow, a reciprocal relationship to FVW classes recorded in the contralateral artery was found.

CONCLUSIONS

UtA FVW patterns recorded during uterine contractions were not predicted by flow patterns recorded during uterine inertia. Reversal of flow direction was more common during oxytocin-induced uterine contractions than during spontaneous contractions. In cases of predominantly reversed flow, domains of the uterus may be supplied by blood from the contralateral UtA. These observations give new insights into the circulatory dynamics of the uterus during labor, and also point to a possible vasoconstrictory effect in the UtAs of oxytocin at high concentrations.

[Uteroplacental haemodynamics and uterine artery Doppler practice at 12 weeks gestation]

Last years, feasibility and possible interest of uterine artery Doppler during the third month of gestation were confirmed. Doppler flow velocity waveforms can be obtained and assessed in both uterine arteries using abdominal ultrasonography at 12-14 weeks' gestation. The no notch group (one third of women) has a low risk for hypertension, intra-uterine growth restriction, abruptio placentae. The "protecting" effect of the absence of uterine artery notch is as high as this physiological change occurs earlier.

Left ventricular concentric geometry as a risk factor in gestational hypertension

In the past, an adverse prognostic significance of an altered left ventricular geometry in essential hypertension has been demonstrated. There are no data on the prognostic significance of an altered cardiac structure during pregnancy. The present study was designed to evaluate the prognostic impact on the outcome of pregnancy of an altered geometry of the left ventricle in mild gestational hypertension. One hundred forty-eight consecutive, pregnant, mild gestational hypertensive women (systolic and diastolic blood pressure, 140 to 150 mm Hg and 90 to 99 mm Hg, respectively) were included in the study. Patients were monitored until term to detect subsequent fetal and/or maternal adverse outcomes (preeclampsia, preterm delivery, abruptio placentae, other maternal medical problems, fetal distress, neonatal low birth weight, admittance to neonatal intensive care unit). One hundred one gestational hypertensive patients (68.2%) had an uneventful pregnancy; 47 patients (31.8%) showed a subsequent development of maternal and/or fetal complications. Concentric geometry was prevalent among patients with the subsequent development of complicated gestational hypertension (37 out of 47 patients) compared with the uneventful gestational hypertensive patients (31 out of 101 patients; 78.7% versus 30.1%; P=0.0001). The multivariate analysis showed concentric geometry as an independent predictor of adverse outcomes (odds ratio, 3.65; 95% confidence interval, 1.30 to 10.27; P=0.014). In patients with gestational hypertension, blood pressure values alone appear to be insufficient to identify the effective risk of adverse events. Ventricular geometry gives additional prognostic information, possibly improving our clinical ability to follow and eventually treat these patients.

Doppler velocimetry in the evaluation of fetal hypoxia

Knowledge of fetal hemodynamic physiology has developed enormously during the last two decades due to Doppler ultrasound. Some of this knowledge has been utilized for routine surveillance of high-risk pregnancies. The prediction of fetal hypoxia before the development of life lasting sequel is of major importance, especially in the very premature case with absent end-diastolic blood flow in the umbilical artery before lung maturity. This review gives an overview of the present knowledge in this field.

Intrauterine growth restriction (IUGR): biometric and Doppler assessment

Intrauterine growth restriction (IUGR) is a common complication in pregnancy and influences morbidity and mortality at all stages of life. Historically, the management of IUGR has been dependent on antenatal biophysical testing and umbilical artery Doppler studies. With recent Doppler studies of the fetal central circulation, including intracardiac flows and the ductus venosus, better timing of delivery to minimize morbidity may be possible. This review will provide the reader with tools to diagnose IUGR, more accurately date the IUGR pregnancy with poor dating criteria, and better assess the condition of the IUGR fetus. A brief review of animal models of IUGR is presented to demonstrate research directions for answering human clinical questions and potentially carrying therapeutic intervention from the bench to the bedside.

Intervillous blood flow in the third trimester gravid rhesus monkey (Macaca mulatta): use of sonographic contrast agent and harmonic imaging

A properly implanted and functioning placenta is essential for the normal outcome of pregnancy. As pregnancy advances, an increasing supply of maternal blood, which reaches the intervillous space of the placenta via the spiral arteries, is necessary for continued growth and development of the fetus. Presumably, deficient blood flow to the intervillous space can lead to placental ischaemia and an unfavourable outcome, such as pre-eclampsia. In this study, we used a primate model, where echocontrast-enhanced harmonic imaging was utilized to demonstrate placental intervillous blood flow without visualization of fetal blood circulation within the chorionic villi. We propose that this technique, which requires further assessment of efficacy and safety prior to use in humans, is a potentially useful non-invasive clinical tool for assessing intervillous blood flow in the third trimester of pregnancy.

The effect of gestational age and placental location on the prediction of pre-eclampsia by uterine artery Doppler velocimetry in low-risk nulliparous women

OBJECTIVE

To assess how placental position and gestational age can influence the value of a diastolic notch of the uterine arteries as a screening test for pre-eclampsia, in a low-risk population of healthy nulliparous women.

METHODS

Color Doppler ultrasound was used to examine both uterine arteries in 654 healthy nulliparas at 4-week intervals between 20 and 32 weeks. The only criterion for an abnormal result was the presence of an early diastolic notch. In each subject the placental position was also recorded. The major end points were pre-eclampsia and pre-eclampsia requiring delivery before the 34th week.

RESULTS

Ninety-eight women (15%) had abnormal flow velocity waveforms at their first visit. Twenty-one out of 654 women developed pre-eclampsia (3.2%). The sensitivity of the test became lower as gestational age advanced and ranged from 81% at 20 weeks, to 71.4% at 32 weeks. In contrast, the specificity and positive predictive value increased significantly. Eleven out of 12 women who delivered before 34 weeks had abnormal waveforms at the 24th week. In women with a full lateral placenta, the predictive value of the test was extremely low, especially in cases with unilateral notches.

CONCLUSION

Pre-eclampsia can be more accurately predicted if, along with the presence of a notch, both gestational age and placental position are taken into account. At week 24 the test maintains a high sensitivity (76.1%), but also has an improved specificity (95.1%) and positive predictive value (34%), which allow the clinician to intervene with a potential preventive treatment.

Quantification of the diastolic notch in Doppler ultrasound screening of uterine arteries

OBJECTIVE

To investigate a new method of quantification of the diastolic notch of the flow velocity waveforms of uterine arteries in the prediction of hypertensive disorders of pregnancy.

METHODS

Pulsed-wave Doppler was used to obtain flow velocity waveforms (FVWs) from the uterine arteries at 21-22 weeks of gestation from 531 nulliparous women and 94 multiparous women at high risk. From the FVWs, both the pulsatility index (PI) and the notch index (NI) were calculated and the predictive values for both indices were compared using logistic regression analysis for mild and severe early onset hypertensive pregnancy complications.

RESULTS

Both the PI and the NI were poor predictors for mild gestational hypertension and pre-eclampsia; predictive values for severe early onset disease, however, were much better. Logistic regression analysis showed the NI has no additional value compared with the PI in the prediction of either mild or severe disease.

CONCLUSIONS

The NI offers the possibility to quantify the diastolic notch in uterine artery analysis. Compared to the PI, this does not lead to better predictive values for hypertensive disorders of pregnancy.

Comprehensive analysis of uterine artery flow velocity waveforms for the prediction of pre-eclampsia

OBJECTIVES

To evaluate the performance of velocimetric indices of uterine artery flow velocity waveforms (FVW's) at 20 weeks' gestation, alone or in combination with qualitative analysis, and establish the optimal screening method for the prediction of pre-eclampsia.

METHODS

A total of 614 primiparous women had color flow/pulsed Doppler (CFPD) imaging of both uterine arteries at 20 weeks gestation. Receiver operator characteristic (ROC) curves were created for the systolic/end-diastolic (A/B) ratio, resistance index (RI) and systolic/early diastolic (A/C) ratio for placental and non-placental uterine arteries, individually or in combination with the presence of unilateral or bilateral notches. Based on data from ROC curves, the sensitivity of each method was compared with the false-positive rate set at 17 and 11%.

RESULTS

The highest sensitivity (88%) and specificity of (83%) was obtained using bilateral notches/mean RI > or = 0.55 (50th centile) and unilateral notches/mean RI > or = 0.65 (80th centile). When the false-positive rate was set at 17%, the inclusion of bilateral notches significantly improved the sensitivity of RI (P < 0.001), placental RI (P < 0.01), placental A/C ratio (P < 0.05), mean A/C ratio (P < 0.01) and mean A/B ratio (P < 0.05). Bilateral notches/mean RI or A/B cut-offs were also superior to the persistence of a notch in either artery combined with RI (P < 0.01) or A/B ratio (P < 0.05). When the false-positive rate was set at 11%, the inclusion of bilateral notches did not improve the sensitivity of the A/C (P = 1.00) or A/B ratio (P > 0.10). Placental velocimetric indices performed better than mean indices but the differences in sensitivity at the set false-positive rates were not statistically significant.

CONCLUSION

At 20 weeks' gestation, bilateral notches with mean RI cut-offs is the best screening method if further screening later in pregnancy is proposed. The A/C ratio is complementary to bilateral notches when the false-positive rate is set at 17% and an effective quantitative substitute when the false-positive rate is set at 11%.