First-trimester uterine artery Doppler indices in the prediction of small-for-gestational age pregnancy and intrauterine growth restriction

First-trimester uterine artery Doppler and adverse pregnancy outcome: a meta-analysis involving 55,974 women

OBJECTIVES

To determine the accuracy with which uterine artery Doppler in the first trimester of pregnancy predicts pre-eclampsia and fetal growth restriction, particularly early-onset disease.

METHODS

We searched MEDLINE (1951-2012), EMBASE (1980-2012) and the Cochrane Library (2012) for relevant citations without language restrictions. Two reviewers independently selected studies that evaluated the accuracy of first-trimester uterine artery Doppler to predict adverse pregnancy outcome and performed data extraction to construct 2 × 2 tables. We synthesized sensitivity and specificity for various Doppler indices using a bivariate random-effects model.

RESULTS

From 1866 citations, we identified 18 studies (55,974 women). The sensitivity and specificity of abnormal uterine artery flow velocity waveform (FVW) in the prediction of early-onset pre-eclampsia were 47.8% (95% CI: 39.0-56.8) and 92.1% (95% CI: 88.6-94.6), and in the prediction of early-onset fetal growth restriction were 39.2% (95% CI: 26.3-53.8) and 93.1% (95% CI: 90.6-95.0), respectively. The sensitivities for predicting any pre-eclampsia and fetal growth restriction were 26.4% (95% CI: 22.5-30.8) and 15.4% (95% CI: 12.4-18.9), respectively, and the specificities were 93.4% (95% CI: 90.4-95.5%) and 93.3% (95% CI: 90.9-95.1), respectively. The number needed to treat (NNT) with aspirin to prevent one case of early-onset pre-eclampsia fell from 1000 to 173 and from 2500 to 421 for background risks varying between 1% and 0.4%, respectively.

CONCLUSIONS

First-trimester uterine artery Doppler is a useful tool for predicting early-onset pre-eclampsia, as well as other adverse pregnancy outcomes. Based on the NNT, abnormal uterine artery Doppler in low-risk women achieves a sufficiently high performance to justify aspirin prophylaxis in those who test positive.

First-trimester screening for early and late small-for-gestational-age neonates using maternal serum biochemistry, blood pressure and uterine artery Doppler

OBJECTIVE

To assess the effectiveness of first-trimester screening for early and late small-for-gestational-age (SGA) neonates using maternal serum biochemistry, blood pressure and uterine artery Doppler.

METHODS

This was a prospective study of 4970 women with a singleton pregnancy who underwent routine first-trimester screening between 2009 and 2011. A logistic regression-based predictive model for SGA, defined as birth weight < 10(th) percentile, divided into early- or late-onset based on gestational age at delivery before or after 34 weeks' gestation, was constructed. The model included maternal baseline characteristics: serum levels of pregnancy-associated plasma protein-A and free β-human chorionic gonadotropin at 8-12 weeks and blood pressure and uterine artery Doppler at 11 + 0 to 13 + 6 weeks.

RESULTS

The prevalence of early and late SGA was 0.6% and 7.9%, respectively. Association with pre-eclampsia was 67% and 8%, respectively. At a false-positive rate of 15%, the detection rate for early SGA was 73%; however it differed substantially for cases with and without pre-eclampsia (90% vs 40%). For late SGA, at false-positive rates of 15 and 50%, detection rates were 32% and 70%, respectively, and did not substantially differ between cases with and without pre-eclampsia.

CONCLUSIONS

First-trimester screening predicts early SGA mainly because of its strong association with pre-eclampsia. Although prediction of late SGA was poorer, at a high false-positive rate it might be considered as part of a first-trimester strategy to select women requiring ultrasound assessment in the third trimester.

Third-trimester abnormal uterine artery Doppler findings are associated with adverse pregnancy outcomes

OBJECTIVES

To evaluate the association between third-trimester abnormal uterine artery Doppler findings and pregnancy outcomes.

METHODS

A prospective study was designed, including 198 consecutive singleton pregnancies between 27 and 41 weeks' gestation. In the study population, 144 had normal uterine artery Doppler waveforms, 37 had unilateral pathologic waveforms, and 17 had bilateral pathologic waveforms. Eighty patients had intrauterine growth restriction (IUGR), preeclampsia toxemia, or both, and 118 had no complications and served as a control group. The uterine artery Doppler waveform was considered abnormal when a notch or pulsatility index above the 90th percentile was noted.

RESULTS

In patients with bilateral pathologic uterine artery Doppler waveforms, the rates of cesarean delivery, small-for-gestational-age (SGA) neonates, preterm delivery, and low Apgar scores were increased compared to patients with normal or pathologic unilateral waveforms (P = .009; P > .001; P = .007; P > .001, respectively). The incidence rates for SGA neonates, cesarean delivery, and preterm delivery were significantly higher among patients without IUGR or preeclampsia toxemia when associated with pathologic bilateral waveforms in comparison to normal waveforms (P = .01 for all). A bilateral pathologic waveform was found to be an independent risk factor for cesarean delivery and SGA neonates. The incidence rates for SGA neonates and preterm delivery were significantly higher among patients with IUGR and/or preeclampsia toxemia when associated with bilateral abnormalities in comparison to normal waveforms (P = .01 for both).

CONCLUSIONS

Third-trimester abnormal uterine artery Doppler findings are associated with worse perinatal outcomes among patients both with and without pregnancy complications.

Decidual natural killer cell interactions with trophoblasts are impaired in pregnancies at increased risk of preeclampsia

Transformation of the uterine spiral arteries (SAs) during pregnancy is critical to support the developing fetus, and is impaired in some pregnancy disorders, including preeclampsia. Decidual natural killer (dNK) cells play a role in SA remodeling, although their interactions with fetal trophoblast remain unclear. A uterine artery Doppler resistance index (RI) in the first trimester of pregnancy can be used as a proxy measure of the extent of SA remodeling; we have used this technique to characterize dNK cells from pregnancies with normal (normal RI) and impaired (high RI) SA remodeling, which display least and highest risk of developing preeclampsia, respectively. We examined the impact of dNK cell secreted factors on trophoblast motility, chemoattraction, and signaling pathways to determine the contribution of dNK cells to SA transformation. We demonstrated that the chemoattraction of the trophoblast by dNK cells is impaired in pregnancies with high RI, as is the ability to induce trophoblast outgrowth from placental villous explants. These processes are dependent on activation of the extracellular signal-regulated kinase 1/2 and phosphatidylinositol 3-kinase-Akt signaling pathways, which were altered in trophoblasts incubated with secreted factors from dNK cells from high RI pregnancies. Therefore, by characterizing pregnancies using uterine artery Doppler RI before dNK cell isolation, we have identified that impaired dNK-trophoblast interactions may lead to poor placentation. These findings have implications for pregnancy pathological conditions, such as preeclampsia.

Uterine artery Doppler velocimetry and obstetric outcomes in connective tissue diseases diagnosed during the first trimester of pregnancy

OBJECTIVE

To evaluate the effect of connective tissue disease (CTD) diagnosed during the first trimester on uterine arteries (UtA) Doppler velocities and on pregnancy outcomes.

METHOD

Pregnant women were screened for CTDs during the first trimester, using a questionnaire, testing for autoantibodies, rheumatologic examination and UtA Doppler evaluations.

RESULTS

Out of 3932 women screened, 491 (12.5%) were screened positive at the questionnaire; of them, 165(33.6%) tested positive for autoantibodies, including 66 eventually diagnosed with undifferentiated connective tissue disease (UCTD), 28 with a definite CTD and 71 with insufficient criteria for a diagnosis. Controls were 326 women screened negative for autoantibodies. In logistic analysis, women diagnosed with either UCTD (OR = 7.9, 95% CI = 2.3-27.3) or overt CTD (OR = 24.9, 95% CI = 6.7-92.4), had increased rates of first trimester bilateral UtA notches compared with controls. The rates of bilateral UtA notches persisting in the second (15/94 vs 0/326, p < 0.001) and third trimesters (7/94 vs 0/326, p < .001) were higher among women with CTDs than in controls. The risk of complications (preeclampsia, fetal growth restriction, prematurity, diabetes, fetal loss) was higher (OR = 7.8, 95% CI = 3.6-17.0) among women with CTDs than in controls.

CONCLUSION

Women with undiagnosed CTDs have higher rates of bilateral UtA Doppler notches throughout pregnancy and increased rates of adverse pregnancy outcomes than controls.

Comparison of two different sites of measurement for transabdominal uterine artery Doppler velocimetry at 11-13 weeks

OBJECTIVES

To compare the feasibility of two transabdominal approaches for performing first-trimester uterine artery (UtA) Doppler and to evaluate the correlation with pulsatility index (PI) in the second trimester.

METHODS

This was a prospective longitudinal Doppler study of the uterine arteries at 11-13 and 21-22 weeks' gestation. Transabdominal ultrasound and color Doppler were used to measure the UtA-PI of the ascending branch of the uterine artery at the level of the internal cervical os (Site A) and at the level of the apparent crossover with the external iliac artery (Site B) at 11-13 weeks, and at Site B only at 21-22 weeks. In all cases the measured left and right PI were converted to a multiple of the median (MoM) for gestational age, and the intercorrelation between the measurements at different sites and gestational ages was calculated using non-parametric analysis (Spearman's rank correlation).

RESULTS

Satisfactory measurements were obtained at 11-13 weeks from both uterine arteries in all 81 women at Site A and in 50 (62%; 95% CI, 50-72%) at Site B (P < 0.01). Measurements were obtained at Site B at 21-22 weeks in all cases. In the 50 cases with measurements from both sites at 11-13 weeks, the correlation of PI-MoMs between Sites A and B at 11-13 weeks was only moderate (ρ = 0.61). The correlation between first-trimester UtA-PI MoMs at Site A and second-trimester UtA-PI MoMs was stronger than that between first-trimester UtA-PI MoMs at Site B and second-trimester UtA-PI MoMs (ρ = 0.73 vs ρ = 0.47, P < 0.01).

CONCLUSION

Evaluation of UtA-PI at 11-13 weeks can be achieved at the level of the internal cervical os in a greater proportion of women than at the level of the apparent crossover with the external iliac vessels, and the measurements obtained correlate better with second-trimester UtA-PI.

Preventing Low Birthweight: 25 years, prenatal risk, and the failure to reinvent prenatal care

In 2010, Preventing Low Birthweight celebrated it 25th anniversary. The report, one of the most influential policy statements ever issued regarding obstetric health care delivery, linked prenatal care to a reduction in low birthweight (LBW). Medicaid coverage for prenatal care services was subsequently expanded and resulted in increased prenatal care utilization. However, the rate of LBW failed to decrease. This well-intentioned expansion of prenatal care services did not change the structure of prenatal care. A single, standardized prenatal care model, largely ineffective in the prevention of LBW, was expanded to a heterogeneous group of patients with a variety of medical and psychosocial risk factors. Reinventing prenatal care as a flexible model, with content, frequency, and timing tailored to maternal and fetal risk, may improve adverse birth outcomes. Risk-appropriate prenatal care may improve the effectiveness of prenatal care for high-risk patients and the efficiency of prenatal care delivery for low-risk patients.

Comparison of uterine artery Doppler in pregnant women with thrombophilia treated by LMWHs and without thrombophilia

OBJECTIVE

The aim of this study was to use uterine artery Doppler ultrasonography to investigate the cases of women with thrombophilia who used LMWH during the 18-22-week period of gestation.

METHODS

This retrospective study was conducted at our university between January 2005 and July 2010. 64 patients were treated with low-dose LMWHs (enoxaparine 40 mg) from the beginning of pregnancy until 36 weeks of gestation. Fifty control subjects were also included in this study. Transabdominal ultrasound examination and bilateral uterine artery Doppler measurements pulsatility index (PI), resistive index (RI), and systole/diastole measurement (S/D) were performed during the 18-22-weeks period of gestation.

RESULTS

No significant differences were found between the groups with respect to maternal age or gestational age at the time of uterine artery Doppler. However, the mean PI (1.07 ± 0.46 for LMWH group and 0.91 ± 0.31 for control, p = 0.036) and the mean RI (0.59 ± 0.12 for LMWH group and 0.54 ± 0.10 for control, p = 0.021) were significantly higher in the trombophilia group.

CONCLUSION

Women with trombophilia still have an increased mean PI and RI, as determined by uterine artery Doppler ultrasonography during the 18-22-week period of gestation, even if they use LMWH.

GRK2 levels in umbilical arteries of pregnancies complicated by gestational hypertension and preeclampsia

BACKGROUND

G-Protein coupled receptor kinase 2 (GRK2) represents a regulator of cell function in different cardiovascular conditions, including high blood pressure. The relationship between elevated GRK2 levels and impaired vasorelaxant responses is causative of hypertension through the increase in vascular resistances. The aim of this study is to ascertain if this feature is present in the fetal placental vasculature of pregnancies complicated by hypertensive disorders.

METHODS

We have assessed GRK2 levels in the umbilical arteries (UA) of 21 preeclamptic or gestational hypertensive and 23 normotensive women at time of delivery.

RESULTS

GRK2 levels were increased in the hypertensive group (0.83 ± 0.14 vs. 0.48 ± 0.06 densitometry units; P < 0.05). GRK2 levels were in correlation and in linear regression with systolic, diastolic, and mean arterial pressure (P < 0.05, r(2) = 0.12, r(2) = 0.11, r(2) = 0.12). Correlations did not reach a significant value for other clinical parameters such as gestational age at birth, umbilical artery pulsatility index, maternal proteinuria, and neonatal birth weight. Out of the 21 hypertensive women, 7 who developed a preeclampsia associated with early preterm delivery (before 34 weeks) had a significantly lower GRK2 levels compared to the remaining 14 (0.51 ± 0.12 vs. 1.08 ± 0.20 densitometry units, P < 0.05).

CONCLUSIONS

We conclude that elevated GRK2 levels in the umbilical vasculature is correlated to elevated blood pressure levels, with a likely compensatory rather than causative role since the lack of protective effect of elevated GRK2 levels may negatively affect the outcome of the hypertensive state.

Evaluation of 7 serum biomarkers and uterine artery Doppler ultrasound for first-trimester prediction of preeclampsia: a systematic review

Preeclampsia (PE) affects 1% to 2% of pregnant women and is a leading cause of maternal and perinatal morbidity and mortality worldwide. The clinical syndrome of PE arises in the second half of pregnancy. However, many underlying factors including defective placentation may already be apparent in the first and early second trimester in many patients. In clinical practice, there is currently no reliable screening method in the first trimester of pregnancy with sufficient accuracy to identify women at high risk to develop PE. Early identification of high-risk pregnancy may facilitate the development of new strategies for antenatal surveillance or prevention and thus improve maternal and perinatal outcome. The aim of this systematic review was to study the literature on the predictive potential of first-trimester serum markers and of uterine artery Doppler velocity waveform assessment (Ut-A Doppler). Literature on the 7 most studied serum markers (ADAM12, fβ-hCG, Inhibin A, Activin A, PP13, PlGF, and PAPP-A) and Ut-A Doppler was primarily selected. In the selected literature, a combination of these markers was analyzed, and where relevant, the value of maternal characteristics was added. Measurements of serum markers and Ut-A Doppler were performed between week 8 + 0 and 14 + 0 GA. Low levels of PP13, PlGF, and PAPP-A and elevated level of Inhibin A have been found to be significantly associated with the development of PE later in pregnancy. The detection rates of single markers, fixed at 10% false-positive rate, in the prediction of early-onset PE were relatively low, and ranged from 22% to 83%. Detection rates for combinations of multiple markers varied between 38% and 100%. Therefore, a combination of multiple markers yields high detection rates and is promising to identify patients at high risk of developing PE. However, large scale prospective studies are required to evaluate the power of this integrated approach in clinical practice.

TARGET AUDIENCE

Obstetricians and Gynecologists, Family physicians Learning Objectives: After completion of this article, the reader should be better able to appraise the recent literature on the development of preeclampsia in the first-trimester, evaluate the predictive value of first-trimester markers and use first-trimester markers, either individually or in combination, to assess the risk of preeclampsia.

Imaging and assessment of placental function

The placenta is the vital support organ for the developing fetus. This article reviews current ultrasound (US) methods of assessing placental function. The ability of ultrasound to detect placental pathology is discussed. Doppler technology to investigate the fetal, placental, and maternal circulations in both high-risk and uncomplicated pregnancies is discussed and the current literature on the value of three-dimensional power Doppler studies to assess placental volume and vascularization is also evaluated. The article highlights the need for further research into three-dimensional ultrasound and alternative methods of placental evaluation if progress is to be made in optimizing placental function assessment.

Pulse pressure and arterial compliance prior to pregnancy and the development of complicated hypertension during pregnancy

We examined the relationship between prepregnant pulse pressure (PP), mean arterial pressure (MAP), cardiac output (CO)/PP, a measure of arterial compliance, and development of complicated hypertension (CH) during pregnancy with the goal of identifying a potential predictor of CH. Twenty nulliparous participants were studied before pregnancy; 17 had normal pregnancies (control; CTL) and 3 CH. Blood pressure monitoring was performed using tonometry. Cardiac output was determined by Doppler echocardiograph. Data are expressed as mean +/- SD. Prepregnant PP was significantly higher in CH participants (CH: 58.3 +/- 6.3, CTL: 46.2 +/- 1.7 mm Hg; P = .02). Cardiac output /pulse pressure was significantly lower in CH participants (CH: 6.9 +/- 1.8, CTL: 10.6 +/- 2.8; P = .04). Mean arterial pressure was not significantly different. Increased PP before pregnancy may suggest increased risk for CH. With accurate prediction of CH before pregnancy, initiation of preventative measures could begin earlier, either prior to or in early pregnancy, potentially increasing preventative efficacy and decreasing CH.

Pre-eclampsia: fitting together the placental, immune and cardiovascular pieces

The success of pregnancy is a result of countless ongoing interactions between the placenta and the maternal immune and cardiovascular systems. Pre-eclampsia is a serious pregnancy complication that arises from multiple potential aberrations in these systems. The pathophysiology of pre-eclampsia is established in the first trimester of pregnancy, when a range of deficiencies in placentation affect the key process of spiral artery remodelling. As pregnancy progresses to the third trimester, inadequate spiral artery remodelling along with multiple haemodynamic, placental and maternal factors converge to activate the maternal immune and cardiovascular systems, events which may in part result from increased shedding of placental debris. As we understand more about the pathophysiology of pre-eclampsia, it is becoming clear that the development of early- and late-onset pre-eclampsia, as well as intrauterine growth restriction (IUGR), does not necessarily arise from the same underlying pathology.

First-trimester placental volume and vascularization measured by 3-dimensional power Doppler sonography in pregnancies with low serum pregnancy-associated plasma protein a levels

OBJECTIVE

The purpose of this study was to investigate the first-trimester placental volume and 3-dimensional (3D) power Doppler vascularization of pregnancies with low serum pregnancy-associated plasma protein A (PAPP-A) levels and to relate these findings to pregnancy outcomes.

METHODS

Three-dimensional power Doppler sonography of the placenta was performed at gestational ages of 11 weeks to 13 weeks 6 days in 84 pregnancies with PAPP-A concentrations of less than 0.4 multiple of the median (MoM). With a standardized setting, the placental volume and vascularization index (VI), flow index (FI), and vascularization-flow index (VFI) were calculated and related to pregnancy outcomes.

RESULTS

Pregnancy outcomes were as follows: 57 pregnancies with birth weights at or above the 10th percentile (group A), 16 pregnancies with birth weights below the 10th percentile and normal Doppler findings in the umbilical artery throughout gestation (group B), and 11 pregnancies with birth weights below the 10th percentile and abnormal umbilical Doppler findings later in gestation (group C). No differences were found in PAPP-A levels among groups. Placental volume values were significantly lower than reference limits, but no differences were found between groups. In groups A and B, there were no significant differences in 3D Doppler indices. However, these indices were significantly lower in group C (VI mean difference, -1.904; P < .001; FI mean difference, -1.939; P < .001; VFI mean difference, -1.944; P < .001). Placental vascular indices were significantly related to the severity of intrauterine growth restriction (IUGR; VI, r = 0.438; P < .001; FI, r = 0.482; P < .001; VFI, r = 0.497; P < .001) but not to the PAPP-A MoM and placental volume values.

CONCLUSIONS

Low serum maternal PAPP-A levels are associated with altered 3D placental Doppler indices, and these changes are related to subsequent development of IUGR and adverse pregnancy outcomes.