The value of uterine artery Doppler in the prediction of uteroplacental complications in multiparous women

A Comparison of Changes in the Mean Arterial Blood Pressure and Mean Uterine Artery Pulsatility Index from 11-14 to 19-24 + 6 Gestation Weeks in Low-Risk and High-Risk Asian Indian Pregnant Women

Aim  The aim of this study was to determine the changes in the mean arterial blood pressure (MAP) and mean uterine artery (UtA) pulsatility index (PI) from 11-14 to 19-24 + 6 gestation weeks in Asian Indian pregnant women. Methods  Clinical and demographic details, MAP, and mean UtA PI measures were ascertained for pregnant women at 11 to 14 gestation weeks and 19-24 + 6 gestation weeks. Women were categorized as a high-or-low risk for preterm preeclampsia using the Fetal Medicine Foundation algorithm and 1 in 150 cutoff. High-risk pregnant women were recommended low-dose aspirin 150 mg daily at bedtime. Changes in MAP and mean UtA PI were compared for gestational age intervals and high-and-low risk women using nonparametric tests. Results  The study analyzed the results of 1,163 pregnant women. Both MAP (mean difference: 5.14, p  < 0.001) and mean UtA PI (mean difference: 0.14, p  < 0.001) remained significantly higher at the second-trimester assessment in high-risk pregnant women compared to low-risk pregnant women. Seventy-seven (35.16%) of the 219 pregnant women with abnormal mean UtA PI in the first trimester had an abnormal mean UtA PI in the second-trimester assessment. One hundred (10.59%) of the 944 pregnant women with normal mean UtA PI in the first trimester had an abnormal mean UtA PI in the 19-24 + 6 weeks assessment. Seventy-seven pregnant women (6.62% of 1,163 women, 95% confidence interval: 5.33, 8.20) had an abnormal mean UtA PI at both gestation age intervals. High-risk pregnant women taking low-dose aspirin daily showed a larger reduction in mean UtA PI compared to high-risk pregnant women that did not report the use of low-dose aspirin (0.89 vs. 0.62, p <0.001) Conclusion  MAP and mean UtA PI decreased significantly from the first to the second trimester of pregnancy. Sequential assessment of the MAP and mean UtA PI in the first and second trimesters of pregnancy will be useful for fetal radiologists in India to identify a subgroup of women with abnormal mean UtA PI at both trimesters that may need more intense surveillance and follow-up till childbirth.

Association Between Serum Matrix Metalloproteinase-2 Levels and Mean Doppler Pulsatility Index of Uterine Arteries in Patients with Preeclampsia

Background: Мatrix metalloproteinase-2 (MMP-2) is an enzye from the gelatinases family involved mainly in collagen degradation. It is also known as a key regulator of normal vascular remodelling during a healthy pregnancy. Failure of regulation of MMP-2 has been associated with abnormal vasodilation, placentation, uterine expansion and development of preeclampsia (PE). Aims: (1) determine serum MMP-2 levels in women with PE and healthy pregnancy, (2) evaluate mean uterine arteries Doppler pulsatility index (UtA PI) and (3) investigate the a possible association between these parameters.

Materials and methods: This was a case-control study. Fifty-five women with PE (mean age 24.9 ± 6 years) and a control group of 35 women with normal pregnancies (mean age 24.7 ± 5.4 years) were examined. An enzyme-linked immunosorbent assay (ELISA) was used to determine serum levels of MMP-2. Mean UtA PI were evaluated by Doppler velocimetry.

Results: Serum ММР-2 levels in preeclampsia were significantly higher than in women with normal pregnancy 11.7 (9.1÷15.5) vs. 7.7 ng/ml (6.5÷13.4) (p = 0.016). Mean UtA PI was significantly higher in preeclampsia than in healthy pregnant women: 1.12 (0.82÷1.5) vs. 0.75 (0.69÷0.85); (p = 0.024). ММР-2 correlated with UtA PI (r = 0.214; p = 0.043). Cutoff value at 14 ng/ml for MMP-2 was found to discriminate between PE and healthy pregnancy.

Conclusion: Our data showed an association between serum MMP-2 and Mean UtA PI. We suggest that MMP-2 could have a potential imply on maternal uterine arteries’ structure, favoring their constriction, increased resistance and abnormal uterine vascular remodeling. Further studies are warranted to clarify whether determination of MMP-2 cutoff value might contribute in the diagnosic work-out strategy for PE.

Third trimester uterine artery Doppler for prediction of adverse perinatal outcomes

PURPOSE OF REVIEW

Abnormal uterine artery Doppler (UtAD) studies early in gestation have been associated with adverse pregnancy outcomes. However, their association with complications in the third trimester is weak. We aim to review the prediction ability for perinatal complications of these indices in the third trimester.

RECENT FINDINGS

Abnormal UtAD waveforms in the third trimester are associated with preeclampsia, small-for-gestational age infants (SGA), preterm birth, perinatal death, and other perinatal complications, such as cesarean section for fetal distress, 5 min low Apgar score, low umbilical artery pH, and neonatal admission to the ICU, particularly in SGA infants. UtAD prediction performance is improved by the addition of maternal characteristics as well as biochemical markers to prediction models and is more precise if the evaluation is made closer to delivery or diagnosis.

SUMMARY

This review shows that the prediction accuracy of UtAD for adverse pregnancy outcomes during the third trimester is moderate at best. UtAD have limited additive value to prediction models that include PlGF and sFlt-1. Serial assessments rather than a single third trimester evaluation may enhance the prediction performance of the UtAD combined models.

A Review of Roles of Uterine Artery Doppler in Pregnancy Complications

The invasion of trophoblasts into the uterine decidua and decidual vessels is critical for the formation of placenta. The defects of placentation are related to the etiologies of preeclampsia (PE), fetal growth restriction (FGR), and small-for-gestational age (SGA) neonates. It is possible to predict significant vascular events during pregnancy through uterine artery Doppler (UAD). From the implantation stage to the end of pregnancy, detecting changes in uterine and placental blood vessels can provide a favorable diagnostic instrument for pregnancy complications. This review aims to collect literature about the roles of UAD in pregnancy complications. We consider all relevant articles in English from January 1, 1983 to October 30, 2021. Predicting pregnancy complications in advance allows practitioners to carry out timely interventions to avoid or lessen the harm to mothers and neonates. Administering low-dose aspirin daily before 16 weeks of pregnancy can significantly reduce the incidence of pregnancy complications. From early pregnancy to late pregnancy, UAD can combine with other maternal factors, biochemical indicators, and fetal measurement data to identify high-risk population. The identification of high-risk groups can also lessen maternal mortality. Besides, through moderate risk stratification, stringent monitoring for high-risk pregnant women can be implemented, decreasing the incidence of adversities.

Personalising cardiovascular network models in pregnancy: A two-tiered parameter estimation approach

Uterine artery Doppler waveforms are often studied to determine whether a patient is at risk of developing pathologies such as pre-eclampsia. Many uterine waveform indices have been developed, which attempt to relate characteristics of the waveform with the physiological adaptation of the maternal cardiovascular system, and are often suggested to be an indicator of increased placenta resistance and arterial stiffness. Doppler waveforms of four patients, two of whom developed pre-eclampsia, are compared with a comprehensive closed-loop model of pregnancy. The closed-loop model has been previously validated but has been extended to include an improved parameter estimation technique that utilises systolic and diastolic blood pressure, cardiac output, heart rate, and pulse wave velocity measurements to adapt model resistances, compliances, blood volume, and the mean vessel areas in the main systemic arteries. The shape of the model-predicted uterine artery velocity waveforms showed good agreement with the characteristics observed in the patient Doppler waveforms. The personalised models obtained now allow a prediction of the uterine pressure waveforms in addition to the uterine velocity. This allows for a more detailed mechanistic analysis of the waveforms, eg, wave intensity analysis, to study existing clinical indices. The findings indicate that to accurately estimate arterial stiffness, both pulse pressure and pulse wave velocities are required. In addition, the results predict that patients who developed pre-eclampsia later in pregnancy have larger vessel areas in the main systemic arteries compared with the two patients who had normal pregnancy outcomes.

Pravastatin plus L-arginine prevents adverse pregnancy outcomes in women with uteroplacental vascular dysfunction

BACKGROUND

Uteroplacental vascular dysfunction, characterized by diminished uterine artery (UtA) blood flow in the second trimester is a clinically useful predictor of the further development of preeclampsia, fetal growth restriction and stillbirth. Efforts to develop effective treatments to protect pregnancies with abnormal UtA Dopplers would be of significant clinical benefit for mothers and their fetuses.

OBJECTIVE

The aim of this pilot non randomized control study was to use pravastatin +L-arginine to improve uteroplacental haemodynamics and prevent adverse maternal and neonatal outcomes in women with abnormal Dopplers and high risk for developing adverse pregnancy outcomes.

STUDY DESIGN

This study was performed between 2015 and 2018. All women received primary care at OB/GYN Polyclinic Jurisic and Narodni Front University Hospital, University of Belgrade Medical School, Serbia. Approval for investigational drug use was obtained and all women gave informed consent. 10 pregnant women with a poor obstetric history that developed uteroplacental dysfunction (UtA pulsatility index (PI) above the 95th percentile and notching) at 20.5 weeks IQR [17.7-22] gave consent to be treated daily with pravastatin (40 mg) and L-arginine (1.5 g) to improve placental blood flow and pregnancy outcomes. 5 women remained untreated after diagnosis at 21 weeks [20-22] (control group). Due to presence of risk factors for pregnancy complications, close maternal and fetal monitoring was undertaken in all patients. Doppler examinations were performed to monitor changes in placental vascular resistance and fetal well-being and growth.

RESULTS

PRAV+L-arginine improved uteroplacental haemodynamics, increased fetal growth and prevented early onset preeclampsia leading to delivery close to term (delivery date: median 38 weeks, IQR[36.5-39]) and appropriate weight for gestational age compared to controls, in which placental blood flow did not improve and 2 women developed severe early onset preeclampsia. Neonates from the control group were born preterm (25 weeks IQR[23.5-25]), growth restricted and spent several months at NICU. Two neonates died due to prematurity-associated complications. PRAV+L-arginine treatment prolonged pregnancies for 4.1 months, compared to 26 days in the untreated group, preventing neonatal complications associated with prematurity. The infants are now 1-3 years old and show normal growth and development.

CONCLUSION

This study describes the successful management with pravastatin+L-arginine of 10 pregnant patients with uteroplacental vascular dysfunction and high risk of adverse maternal and fetal outcomes. A larger study is being organized to confirm these observations.

Uterine Artery Doppler Ultrasonography for First Trimester Prediction of Preeclampsia in Individuals at Risk from Low-Resource Settings

Background and objectives: The objective of this study was to evaluate the potential of first trimester uterine artery Doppler ultrasonography for the early prediction of preeclampsia (PE), in at-risk pregnant women. Materials and Methods: This was a prospective longitudinal study, including 120 Caucasian pregnant women with risk factors for PE. The potential of pulsatility indexes (PI) and notch was assessed as a tool for preeclampsia screening. Results: Doppler examination of the uterine artery performed early at 11-14 WA allows the detection of pregnancies that will develop PE with a sensitivity of 61.5% and a specificity of 63.8% based on PI analysis. Predictive power increases slightly by adding bilateral notch (sensitivity = 65.4%; specificity = 66%). Conclusions: Uterine artery Doppler examination is an effective non-invasive screening test for the development of PE in pregnancies at risk, particularly appropriate in health systems with limited means of evaluating other biomarkers.

Prognostic role of uterine artery Doppler in early- and late-onset preeclampsia with severe features

OBJECTIVE

To correlate uterine artery Doppler findings with maternal and neonatal outcomes in early- and late-onset preeclampsia with severe features.

METHODOLOGY

Doppler scan was done in both uterine arteries. Maternal and neonatal outcomes in women with abnormal and normal Doppler results were compared.

RESULTS

Abnormal Doppler results were present in 45 women (75%). Thirty-four (56.7%) women had abnormal RI, 19 (31.6%) had abnormal PI, and 36 (60%) had diastolic notch. Of the women who participated in the study, 21.6% developed maternal complications, and the majority belonged to the early-onset severe preeclampsia group. Diastolic notch was twofold more frequent in the early group. RI was abnormal in 63% of the early-onset and 50% of the late-onset group.

CONCLUSION

Pregnancies with early-onset preeclampsia who had abnormal uterine artery Doppler findings were at high risk for both maternal and neonatal complications, whereas those who had late-onset preeclampsia with abnormal Doppler findings only had an increased risk of perinatal complications.

No. 197a-Fetal Health Surveillance: Antepartum Consensus Guideline

OBJECTIVE

This guideline provides new recommendations pertaining to the application and documentation of fetal surveillance in the antepartum period that will decrease the incidence of birth asphyxia while maintaining the lowest possible rate of obstetrical intervention. Pregnancies with and without risk factors for adverse perinatal outcomes are considered. This guideline presents an alternative classification system for antenatal fetal non-stress testing to what has been used previously. This guideline is intended for use by all health professionals who provide antepartum care in Canada.

OPTIONS

Consideration has been given to all methods of fetal surveillance currently available in Canada.

OUTCOMES

Short- and long-term outcomes that may indicate the presence of birth asphyxia were considered. The associated rates of operative and other labour interventions were also considered.

EVIDENCE

A comprehensive review of randomized controlled trials published between January 1996 and March 2007 was undertaken, and MEDLINE and the Cochrane Database were used to search the literature for all new studies on fetal surveillance antepartum. The level of evidence has been determined using the criteria and classifications of the Canadian Task Force on Preventive Health Care (Table 1).

SPONSOR

This consensus guideline was jointly developed by the Society of Obstetricians and Gynaecologists of Canada and the British Columbia Perinatal Health Program (formerly the British Columbia Reproductive Care Program or BCRCP) and was partly supported by an unrestricted educational grant from the British Columbia Perinatal Health Program. RECOMMENDATION 1: FETAL MOVEMENT COUNTING: RECOMMENDATION 2: NON-STRESS TEST: RECOMMENDATION 3: CONTRACTION STRESS TEST: RECOMMENDATION 4: BIOPHYSICAL PROFILE: RECOMMENDATION 5: UTERINE ARTERY DOPPLER: RECOMMENDATION 6: UMBILICAL ARTERY DOPPLER.

A data-driven model to study utero-ovarian blood flow physiology during pregnancy

In this paper, we describe a mathematical model of the cardiovascular system in human pregnancy. An automated, closed-loop 1D-0D modelling framework was developed, and we demonstrate its efficacy in (1) reproducing measured multi-variate cardiovascular variables (pulse pressure, total peripheral resistance and cardiac output) and (2) providing automated estimates of variables that have not been measured (uterine arterial and venous blood flow, pulse wave velocity, pulsatility index). This is the first model capable of estimating volumetric blood flow to the uterus via the utero-ovarian communicating arteries. It is also the first model capable of capturing wave propagation phenomena in the utero-ovarian circulation, which are important for the accurate estimation of arterial stiffness in contemporary obstetric practice. The model will provide a basis for future studies aiming to elucidate the physiological mechanisms underlying the dynamic properties (changing shapes) of vascular flow waveforms that are observed with advancing gestation. This in turn will facilitate the development of methods for the earlier detection of pathologies that have an influence on vascular structure and behaviour.

Prenatal air pollution exposure, smoking, and uterine vascular resistance

Supplemental Digital Content is available in the text.

Background:

Prenatal exposure to air pollution and smoking increases the risk of pregnancy complications and adverse birth outcomes, but pathophysiologic mechanisms are still debated. Few studies to date have examined the influence of air pollution on uterine vascular resistance, and no studies have examined the independent impact of these exposures. We aimed to assess the impact of prenatal exposure to traffic-related air pollution and smoking on uterine vascular resistance.

Methods:

Our study included 566 pregnant women recruited between 1993 and 1996 in Los Angeles who completed visits at three gestational ages. Information on smoking was collected, and uterine vascular resistance was measured at each visit by Doppler ultrasound. We calculated three resistance indices: the resistance index, the pulsatility index, and the systolic/diastolic ratio. We estimated exposure to NO₂ at the home address of the mother using a land use regression model and to nitrogen oxides using CALINE4 air dispersion modeling. We used generalized linear mixed models to estimate the effects of air pollution and smoking on uterine vascular resistance indices.

Results:

Land use regression–derived NO₂ and CALINE4-derived nitrogen oxides exposure increased the risk of high uterine artery resistance in late pregnancy. Smoking during pregnancy also increased the risk of higher uterine resistance and contributed to bilateral notching in mid-pregnancy.

Conclusion:

Our results suggest that uterine vascular resistance is a mechanism underlying the association between smoking and air pollution and adverse birth outcomes.

Risk Factors for Adverse Fetal Outcome in Hemodialysis Pregnant Women

Introduction

Pregnancy in women on dialysis is associated with a higher risk of adverse events, and the best care for this population remains to be established.

Methods

In this series, we aimed to identify factors associated with the risk of adverse fetal outcomes among 93 pregnancies in women on hemodialysis. Dialysis dose was initially assigned according to the presence of residual diuresis, body weight, and years on dialysis. Subsequent adjustments on dialysis dose were performed according to several parameters.

Results

The overall successful delivery rate was 89.2%, with a dialysis regimen of 2.6 ± 0.7 h/d, 15.4 ± 4.0 h/wk, and mean weekly standard urea Kt/V of 3.3 ± 0.6. In the logistic models, preeclampsia, lupus, primigravida, and average midweek blood urea nitrogen (BUN) level were positively related to the risk of a composite outcome of perinatal death or extreme prematurity, whereas polyhydramnios was inversely related to it. In multivariable linear regression, preeclampsia, polyhydramnios, primigravida, average midweek BUN, and residual diuresis remained significantly and independently related to fetal weight, which is a surrogate marker of fetal outcome. An average midweek BUN of 35 mg/dl was the best value for discriminating the composite outcome, and BUN ≥35 mg/dl was associated with a significant difference in a Kaplan-Meier curve (P = 0.01).

Conclusion

Our results showed that a good fetal outcome could be reached and that preeclampsia, lupus, primigravida, residual diuresis, polyhydramnios, and hemodialysis dose were important variables associated with this outcome. In addition, we suggested that a midweek BUN <35 mg/dl might be used as a target for adjusting dialysis dose until hard data were generated.

Maternal uterine artery Doppler in the first and second trimesters as screening method for hypertensive disorders and adverse perinatal outcomes in low-risk pregnancies

Objective

To assess the maternal demographic characteristics and uterine artery (UA) Doppler parameters at first and second trimesters of pregnancy as predictors for hypertensive disorders (HDs) and adverse perinatal outcomes.

Methods

This prospective cohort study comprised 162 singleton low-risk women undergoing routine antenatal care. The left and right UA were assessed by color and pulsed Doppler and the mean pulsatility and resistance indices as well as the presence of a bilateral protodiastolic notch were recorded at 11 to 14 and 20 to 24 weeks' gestation. Multilevel regression analysis was used to determine the effects of maternal characteristics and abnormal UA Doppler parameters on the incidence of HD, small for gestational age newborn, cesarean section rate, Apgar score <7 at 1st and 5th minute, and admission to the neonatal intensive care unit.

Results

Fifteen women (9.2%) developed HD. UA mean resistance index (RI), UA mean pulsatility index, and parity were independent predictors of HD. Compared to the pregnancies with a normal UA mean RI at the first and second trimesters, pregnancies with UA mean RI >95th percentile only at the first trimester showed an increased risk for HD (odds ratio, 23.25; 95% confidence interval, 3.47 to 155.73; P<0.01). Similar result was found for UA mean pulsatility index >95th percentile (odds ratio, 9.84; 95% confidence interval, 1.05 to 92.10; P=0.05). The model including maternal age, maternal and paternal ethnicity, occupation, parity and UA mean RI increased the relative risk for HD (area under receiver operating characteristics, 0.81).

Conclusion

A first-trimester screening combining maternal characteristics and UA Doppler parameters is useful to predict HD in a low-risk population.

Pregnancy in patients with chronic kidney disease: Maternal and fetal outcomes

Chronic kidney diseases (CKD) adversely affects fetal and maternal outcomes during pregnancy. We retrospectively reviewed the renal, maternal and fetal outcomes of 51 pregnancies in women with CKD between July 2009 and January 2012. Of the 51 subjects (mean age 27.8 ± 7.04), 32 had 19 had estimated glomerular filtration rate (eGFR) <60 ml/min. There was significantly greater decline in eGFR at 6 weeks (55.8 ± 32.7 ml/min) after delivery as compared to values at conception (71.7 ± 27.6 [P < 0.001]). The average decline of GFR after 6 weeks of delivery was faster in patients with GFR < 60 ml/min/1.73 m(2) at -18.8 ml/min (stage 3, n = 13, -20.2 ml/min; stage 4, n = 6, -15.8 ml/min) as compared to -15.1 ml/min in patients with GFR ≥ 60 ml/min/1.73 m(2). Three of the six patients (50%) in stage 4 CKD were started on dialysis as compared to none in earlier stages of CKD (P = 0.002). At the end of 1 year, all patients in stage 4 were dialysis dependent, while only 2/13 in stage 3 were dialysis dependent (Odds ratio 59.8, 95% confidence interval 2.8-302, P = 0.001). Preeclampsia (PE) was seen in 17.6%. Only 2/32 (6.25%) patients with GFR ≥ 60 ml/min/1.73 m(2) developed PE while 7/19 (36.84%) patients with GFR < 60 ml/min developed PE. Of the 51 pregnancies, 15 ended in stillbirth and 36 delivered live births. Eleven (21.56%) live-born infants were delivered preterm and 7 (13.72%) weighed < 2,500 g. The full-term normal delivery was significantly high (50%) in patients with GFR ≥ 60 ml/min/1.73 m(2) (P = 0.006) and stillbirth was significantly high - 9/19 (47.36%) patients with GFR < 60 ml/min/1.73 m(2). To conclude, women with CKD stage 3 and 4 are at greater risk of decline in GFR, PE and adverse maternal and fetal outcomes as compared to women with earlier stages of CKD.

Could first-trimester assessment of placental functions predict preeclampsia and intrauterine growth restriction? A prospective cohort study

OBJECTIVE

To examine the role of first-trimester uterine artery Doppler, serum β-hCG and pregnancy-associated placental protein-A (PAPP-A) in prediction of preeclampsia and IUGR.

METHODS

A total of 100 pregnant women in the 11-14 weeks' gestation were examined using uterine artery Doppler, serum β-hCG and PAPP-A. All women were followed-up for development of preeclampsia or IUGR.

RESULTS

A total of 94 women completed the study of which 7 (7.4%) developed complications. Uterine artery PI and RI were significantly higher whereas serum β-hCG and PAPP-A levels were significantly reduced in patients who developed complications when compared with those who did not. Uterine artery PI had the highest sensitivity (100%) but a low specificity (56% and 45%) in prediction of preeclampsia and IUGR, respectively. Adding PAPP-A to uterine artery PI elevated the specificity into 94.44% and 95.51%, respectively. Combined PI and β-hCG elevated the specificity into 88.89% and 89.89%, respectively.

CONCLUSION

Our study suggests that first-trimester uterine artery impedance, as measured by Doppler ultrasound as well as low serum biomarkers (β-hCG and PAPP-A) can be used for prediction of preeclampsia and IUGR. The most sensitive is uterine artery PI. Adding β-hCG to PI improves specificity in prediction of both preeclampsia and IUGR. Uterine artery PI plus PAPP-A is the best combination for prediction of both preeclampsia and IUGR.

Uterine Artery Doppler of the Gravid Uterus as a Predictor Identifying At-Risk Pregnancies

Uterine artery Doppler has been a useful aid in the sonographic evaluation of uteroplacental hemodynamics of the gravid uterus. Pulsatility index, resistive index, and systolic/diastolic ratio can be calculated and interpreted in the evaluation of blood flow. The waveform itself can be evaluated for diastolic notching and used to interpret the qualitative appearance of the blood flow. In addition to the hemodynamic characteristics, practitioners have incorporated maternal serum tests to attempt to isolate at-risk candidates. This article summarizes the effectiveness of each methodology, with a primary focus on an at-risk population, since studies of low-risk populations have not demonstrated significant sensitivity for prediction of complications such as pre-eclampsia, placental abruptia, or fetal demise.

Uterine artery Doppler longitudinal changes in pregnancies complicated with intrauterine growth restriction without preeclampsia

OBJECTIVE

The objective of this article is to evaluate the longitudinal changes in uterine artery Doppler pulsatility index (UtA-PI) in pregnancies complicated with early onset intrauterine growth restriction (IUGR).

METHOD

Case-control study comparing UtA-PI from 20 to 34 weeks gestation in pregnancies affected by IUGR at 20 to 28 weeks and confirmed at delivery (cases), matched with 1000 controls. Multivariable analyses were used to estimate the UtA-PI as a function of both gestational age and IUGR severity. Finally, bootstrapping technique was used to internally validate the models.

RESULTS

We retrospectively retrieved 53 cases and 1000 controls. Regression line having log10 UtA-PI as dependent variable was a function of both gestational age and IUGR. UtA-PI decreased with gestational age in both groups. In IUGR group, UtA-PI was higher from 20 weeks onward and the difference with controls increased with gestational age. In fact, at 20 weeks, the UtA-PI ratio between cases and controls was 1.84, but at 30 weeks it rose to 2.05. Finally, the weight at delivery in the IUGR group was also inversely correlated with the UtA-PI values.

CONCLUSION

We presented a reliable multivariable statistical model to evaluate the temporal changes of UtA-PI values as a function of both gestational age and IUGR.

Aspirin and preeclampsia prevention in patients with abnormal uterine artery blood flow

Background:

Preeclampsia is one of the leading causes of maternal mortality and morbidity. Its prevalence varies between 10-25% among high-risk pregnant patients.

Objectives:

The aim of this study was to determine whether treatment with acetylsalicylic acid (ASA) reduces the incidence of preeclampsia among pregnant women with abnormal uterine artery flow.

Patients and Methods:

In this double-blind, placebo controlled trial, 80 high-risk pregnant women with preeclampsia, who had abnormal findings on Doppler ultrasonography at 12-16 weeks of pregnancy (unilateral notch with RI ≥ 0.65 or bilateral notch with RI ≥ 0.55), were randomly divided into two groups; the intervention group was treated with ASA tablet 80 mg, one tablet per day, and the control group was given placebo. Then patients were followed until the end of their pregnancy period, and pregnancy outcomes, including development of preeclampsia, the intrauterine growth retardation (IUGR), prematurity, type of delivery, birth weight, and Apgar score at one and five minutes were assessed. Data were analyzed using the student's t-test, chi-square or Fisher's exact test, and multivariate logistic regression. P values less than 0.05 were considered statistically significant.

Results:

There were no significant differences between the two groups in terms of baseline characteristics. There was a significant difference between the ASA and placebo groups in the incidence of preeclampsia (2.5% versus 22.5%), adjusting for the neonatal and maternal covariates.

Conclusions:

ASA prophylaxis can be used for prevention of preeclampsia in high-risk patients with abnormal uterine artery.

Second-trimester prediction of delivery of a small-for-gestational-age neonate: integrating sequential Doppler information, fetal biometry, and maternal characteristics

OBJECTIVE

The aim of this study was to investigate the predictive accuracy of second-trimester ultrasound parameters, maternal characteristics, and sequential Doppler changes between first and second trimesters for the prediction of small-for-gestational-age (SGA) infants (birth weight < 10th percentile).

METHODS

We conducted a prospective study of singleton pregnancies enrolled in the first trimester with subsequent second-trimester follow-up. Maternal characteristics, uterine artery (UtA) pulsatility index (PI), fetal biometry, and umbilical artery (UA)-PI were ascertained. UtA and UA-PI change from first to second trimester was calculated (ΔUtA-PI and ΔUA-PI). These parameters were tested for their ability to predict delivery of an SGA infant.

RESULTS

Among 1982 women, 172 delivered an SGA neonate. African-American ethnicity, nulliparity, tobacco use, and low abdominal circumference (AC) z-score were independent predictors of SGA. No difference was found in the magnitude of ΔUtA-PI and ΔUA-PI between SGA and no-SGA. Receiver-operating characteristics curve analysis yielded an area under the curve of 0.700 for AC z-score. The combination of low AC and bilateral notching had high specificity (99%) but low sensitivity (7%) for SGA prediction.

CONCLUSIONS

A small second-trimester fetal AC is a specific marker for SGA when found with bilateral UtA notching. Only a small proportion is predicted by the factors studied, suggesting a small contributory role or later evolution of SGA.

Second- and third-trimester placental hemodynamics and the risks of pregnancy complications: the Generation R Study

Characteristics of the uterine and umbilical artery blood flow patterns are indirect measures of uteroplacental circulation. We examined whether uterine and umbilical artery resistance indices are influenced by maternal demographic and lifestyle characteristics, track from the second trimester to the third, and are associated with the risk of pregnancy complications. This analysis was embedded among 7,660 pregnant women in the Generation R Study (Rotterdam, the Netherlands, 2001-2005). Placental resistance indices were assessed in the second and third trimesters. Information about pregnancy outcomes was obtained from medical records. Maternal characteristics affected second- and third-trimester placental resistance indices. Correlation coefficients for correlation between the second and third trimesters were 0.50 and 0.32 for uterine artery resistance index and umbilical artery pulsatility index, respectively. Higher placental resistance indices in the second and third trimesters and persistence in the highest tertile of uterine artery resistance index from the second trimester to the third were associated with the risks of preeclampsia, preterm birth, and small size for gestational age at birth (all P's < 0.05). Our study shows that placental resistance indices are influenced by maternal demographic and lifestyle characteristics and track moderately from the second trimester to the third. Increased placental resistance indices in the second and third trimesters are associated with increased risks of adverse pregnancy outcomes.

First trimester growth restriction and uterine artery blood flow in the second trimester as predictors of adverse pregnancy outcome

OBJECTIVES

To investigate if fetuses with first trimester growth restriction have poorer perfusion of the placenta compared to a control group, and to investigate whether first trimester growth restriction in combination with poor flow in the uterine arteries in the second trimester can be used to predict poor outcome.

STUDY DESIGN

Women with singleton pregnancies, where the gestational age estimated by crown-rump length (CRL) at the first trimester scan was 7 days or more smaller than the gestational age estimated by last menstrual period, and a control group of women, where the gestational age was either equal to or 1 day larger than the gestational age estimated by last menstrual period, were invited to join the study. The study entailed the routine scans; Down syndrome screening in gestational week 11-14 and an anomaly scan in gestational week 18-21. In addition to the routine scans the participants were offered a growth scan in gestational week 23-24. At the anomaly scan and growth scan, umbilical and uterine artery Doppler flows were measured.

RESULTS

182 cases and 230 controls were included in the study. The case and control groups showed no significant differences in placental blood flow characteristics at 18-21 weeks or 23-24 weeks. In our logistic regression models the only outcome that showed a significant association to the case group was birth weight below 2500 g. Having a CRL 7 days or more smaller than expected increased the risk of having a child with a birth weight below 2500 g with an odds ratio of 3.29.

CONCLUSIONS

We were unable to demonstrate a link between first trimester growth restriction and poor placental perfusion. The case group had increased risk of birth weight below 2500 g, but only with an odds ratio of 3. Therefore we do not recommend implementation of uterine or umbilical artery flow measurements specifically for fetuses with first trimester growth restriction.

Significance of uteroplacental Doppler at midtrimester in patients with favourable obstetric history

OBJECTIVE

To reassess the usefulness of midtrimester uterine Doppler in low-risk multiparous women.

METHODS

We prospectively recruited low-risk pregnant women at 20-22 weeks attending our clinic. Among those, women with a favourable obstetric history (group A) were distinguished from nulliparous (group B) and of each group we measured uterine artery Doppler (pulsatility index (PI)). We evaluated the accuracy of uterine artery Doppler in the prediction of preeclampsia and small for gestational age (SGA) neonates.

RESULTS

Between January 2009 and October 2010, 382 women were included in the study of which 147 in group A and 235 in group B. Overall, 26/382 (6.8%) women presented preeclampsia and SGA occurred in 59/382 (15.4%) cases. In our population, at a 10% false positive rate (FPR) uterine artery Doppler showed a detection rate (DR) of 19.2% for preeclampsia and of 37.3% for SGA, with a higher sensitivity for SGA neonates delivered ≤ vs. >34 weeks (87% vs. 29.4%). The univariable receiver operating characteristics (ROC) curve by uterine artery PI yielded a significant prediction only for SGA in nulliparous women (areas under the curve (AUC) of 0.70; 95% CI 0.60-0.79).

CONCLUSIONS

Our data confirmed that midtrimester uterine artery Doppler is not an efficient strategy in anticipating the risk of pregnancy complications among low-risk multiparous women.

Left ventricular midwall mechanics at 24 weeks' gestation in high-risk normotensive pregnant women: relationship to placenta-related complications of pregnancy

OBJECTIVES

Most studies during pregnancy have assessed maternal left ventricular (LV) function by load-dependent indices, assessing only chamber function. The aim of this study was to assess afterload-adjusted LV myocardial and chamber systolic function at 24 weeks' gestation and 6 months postpartum in high-risk normotensive pregnant women.

METHODS

A group of 118 high-risk women with bilateral notching of the uterine arteries underwent an echocardiographic examination to evaluate midwall mechanics (midwall shortening (mFS%) and stress-corrected midwall shortening (SCmFS%)) of the LV at 24 weeks' gestation and 6 months postpartum. Patients were followed until delivery and pregnancies were classified retrospectively as uneventful (uncomplicated outcome) or complicated. A control group of 54 low-risk women with uneventful pregnancies without bilateral notching was also enrolled.

RESULTS

The pregnancy was uneventful in 74 (62.7%) women, whereas 44 (37.3%) developed complications. At 24 weeks' gestation, mFS% and SCmFS% were greater in the uncomplicated-outcome compared with the complicated-outcome group (25.9 ± 4.8 vs 18.8 ± 5.0%, P < 0.001 and 107.9 ± 18.4 vs 77.9 ± 20.7%, P < 0.001, respectively). At 6 months postpartum, SCmFS% remained greater in the uncomplicated-outcome compared with the complicated-outcome group (100.4 ± 21.6 vs 87.8 ± 19.1, P < 0.05). In the uncomplicated-outcome group, SCmFS% was higher during pregnancy than it was postpartum, whereas in the complicated-outcome group, it was lower during pregnancy than it was postpartum (P < 0.05).

CONCLUSIONS

Maternal cardiac midwall mechanics appear to be enhanced (SCmFS% increased compared with controls) during pregnancy compared with postpartum in high-risk patients with uncomplicated pregnancy, whereas midwall mechanics are depressed both during pregnancy and postpartum in patients with pregnancy complications.

High-end arteriolar resistance limits uterine artery blood flow and restricts fetal growth in preeclampsia and gestational hypertension at high altitude

The reduction in infant birth weight and increased frequency of preeclampsia (PE) in high-altitude residents have been attributed to greater placental hypoxia, smaller uterine artery (UA) diameter, and lower UA blood flow (Q(UA)). This cross-sectional case-control study determined UA, common iliac (CI), and external iliac (EI) arterial blood flow in Andeans residing at 3,600-4,100 m, who were either nonpregnant (NP, n = 23), or experiencing normotensive pregnancies (NORM; n = 155), preeclampsia (PE, n = 20), or gestational hypertension (GH, n = 12). Pregnancy enlarged UA diameter to ~0.62 cm in all groups, but indices of end-arteriolar vascular resistance were higher in PE or GH than in NORM. Q(UA) was lower in early-onset (≤34 wk) PE or GH than in NORM, but was normal in late-onset (>34 wk) illness. Left Q(UA) was consistently greater than right in NORM, but the pattern reversed in PE. Although Q(CI) and Q(EI) were higher in PE and GH than NORM, the fraction of Q(CI) distributed to the UA was reduced 2- to 3-fold. Women with early-onset PE delivered preterm, and 43% had stillborn small for gestational age (SGA) babies. Those with GH and late-onset PE delivered at term but had higher frequencies of SGA babies (GH=50%, PE=46% vs. NORM=15%, both P < 0.01). Birth weight was strongly associated with reduced Q(UA) (R(2) = 0.80, P < 0.01), as were disease severity and adverse fetal outcomes. We concluded that high end-arteriolar resistance, not smaller UA diameter, limited Q(UA) and restricted fetal growth in PE and GH. These are, to our knowledge, the first quantitative measurements of Q(UA) and pelvic blood flow in early- vs. late-onset PE in high-altitude residents.

Antithrombotic therapy for improving maternal or infant health outcomes in women considered at risk of placental dysfunction

BACKGROUND

Pregnancy complications such as pre-eclampsia and eclampsia, intrauterine growth restriction and placental abruption are thought to have a common origin related to abnormalities in the development and function of the placenta.

OBJECTIVES

To compare, using the best available evidence, the benefits and harms of antenatal antithrombotic therapy to improve maternal or infant health outcomes in women considered at risk of placental dysfunction, when compared with other treatments, placebo or no treatment.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (March 2010).

SELECTION CRITERIA

Randomised controlled trials comparing antenatal antithrombotic therapy (either alone or in combination with other agents) with placebo or no treatment, or any other treatment in the antenatal period to improve maternal or infant health outcomes in women considered at risk of placental dysfunction.

DATA COLLECTION AND ANALYSIS

Two review authors evaluated trials under consideration for appropriateness for inclusion and methodological quality without consideration of their results according to the prestated eligibility criteria. We used a fixed-effect meta-analysis for combining study data if the trials were judged to be sufficiently similar. We investigated heterogeneity by calculating I(2) statistic, and if this indicated a high level of heterogeneity among the trials included we used a random-effects model.

MAIN RESULTS

Our search strategy identified 14 reports of 10 studies for consideration, of which five met the inclusion criteria, involving 484 women. Four studies compared heparin (alone or in combination with dipyridamole) with no treatment; and one compared trapidil (triazolopyrimidine). While there were no statistically significant differences identified for the primary outcomes following heparin treatment, it was associated with a reduction in the risk of pre-eclampsia, eclampsia, and infant birthweight less than the 10th centile for gestational age.

AUTHORS' CONCLUSIONS

The review identified no significant differences for the primary outcomes perinatal mortality, preterm birth less than 34 weeks' gestation, and childhood neurodevelopmental handicap, although the number of studies and participants was small. While treatment with heparin appears promising with a reduction in pre-eclampsia, eclampsia, and infant birthweight less than the 10th centile for gestational age, the number of studies and participants included was small, and to date important information about serious adverse infant and long-term childhood outcomes is unavailable. Further research is required.

Clinical and ultrasound work-up and follow-up of preeclampsia

Hypertensive disorders are frequent during pregnancy and are related with an important morbidity and mortality worldwide. In this review we aim to provide the reader with a comprehensive overview of the clinical aspects of and the diagnostic tools used in the primary assessment and the (long term) follow-up of preeclampsia. The focus in this review will lay on the clinical follow-up of both the mother and the fetus aiming at the prevention of severe maternal complications as well as preventing growth restriction and prematurity in the child.

Platelet activation and endogenous thrombin potential in pre-eclampsia

INTRODUCTION

Platelets and the coagulation system may be involved in the pathogenesis of pre-eclampsia. We investigated whether platelet and coagulation activation markers, are elevated in pre-eclampsia.

MATERIALS/METHODS

Case-control study in which activated platelets, platelet-monocyte/ neutrophil aggregates, platelet microparticles (measured by flow cytometry) and four markers of thrombin generation capacity (endogenous thrombin potential (ETP), peak height, lag time and time to peak) using the Calibrated Automated Thrombogram system were assessed in pregnant women of similar gestational age with (n=46) and without (n=46) pre-eclampsia, and in healthy non-pregnant women (n=42).

RESULTS

The percentage of, CD62P+ platelets (p=0.013), CD62P+ platelet microparticles (p=0.029) and platelet-monocyte aggregates (p=0.019) were significantly higher in women with pre-eclampsia than the pregnant controls. Both groups of pregnant women had significantly higher ETP and peak height (p <0.001) than the healthy non pregnant group and the women with pre-eclampsia had significantly higher ETP and peak height (p<0.001) than the normotensive pregnant controls.

CONCLUSION

In the most comprehensive laboratory analysis to date, we found evidence of both platelet and coagulation activation in women with pre-eclampsia.

Relationship between prepregnancy and early pregnancy uterine blood flow and resistance index

We evaluated the relationship between prepregnancy and early pregnancy uterine blood flow (UBF) and resistance index (RI). Nineteen nulliparous participants were studied during cycle day 8 + 4, and early pregnancy (13.4 + 1.6 weeks). Color Doppler ultrasound of both uterine arteries and maternal heart was performed to calculate uterine RI, volumetric UBF, and cardiac output (CO), respectively. We observed a strong negative association of uterine RI with prepregnancy UBF (r = -.82, P < .001) that weakened, but remained significant in early pregnancy (r =-.48, P = .04). Prepregnancy uterine index (UBF/CO) was significantly associated with early pregnancy uterine index; r = .48, P = .04). There was also a trend associating prepregnancy and early pregnancy volumetric UBF (r = .44, P = .068). Prepregnancy UBF may be a determinant of early pregnancy UBF and UBF may have independent value as a predictor of adverse pregnancy outcome.

Uterine artery Doppler flow studies in obstetric practice

The advent of sonography has changed the practice of obstetrics by providing a window to the womb through which the anatomic structure of the fetus can be evaluated. The addition of Doppler flow studies of maternal and fetal vessels has provided a tool where the physiology of the maternal-fetal unit can be assessed. This information can provide the physician and the patient with vital information for a subsequent approach to the pregnancy. The use of fetal Doppler blood flow studies has become common in the evaluation and management of pregnancies complicated by conditions such as suspected fetal growth restriction and red blood cell isoimmunization to guide intrauterine therapy and delivery. The most commonly assessed Doppler flow studies of the fetus are the umbilical artery and middle cerebral artery (MCA). Doppler flow studies of the MCA are used in the assessment of the fetus at risk for anemia and growth-restricted fetus. Doppler flow studies of the umbilical artery can reflect abnormalities in "down-stream" or the fetal side of placental resistance, and the assessment of the maternal vasculature evaluates "up-stream" blood flow or the maternal side of placental resistance. The purpose of this review is to describe the clinical utility of uterine artery Doppler flow studies in the prediction of adverse pregnancy outcomes in low and high risk populations.

Pulse wave analysis: a preliminary study of a novel technique for the prediction of pre-eclampsia

OBJECTIVE

To investigate whether first-trimester arterial pulse wave analysis (PWA) can predict pre-eclampsia.

DESIGN

This was a prospective screening study.

SETTING

The Homerton University Hospital, a London teaching hospital.

POPULATION

Two hundred and ten low-risk women with a singleton pregnancy were analysed.

METHODS

Radial artery pulse waveforms were measured between the 11(+0) and 13(+6) weeks of gestation and the aortic waveform derived by applying a generalised transfer function. Augmentation pressure (AP) and augmentation index at heart rate of 75 beats per minute (AIx-75), measures of arterial stiffness, were calculated. The multiple of the gestation-specific median in controls for AP and AIx-75 were calculated. Logistic regression models were developed and their predictive ability assessed using the area under the receiver operator curve.

MAIN OUTCOME MEASURES

Prediction of pre-eclampsia by AIx-75.

RESULTS

Fourteen (6.7%) women developed pre-eclampsia, and 196 remained normotensive. Eight of the 14 women developed pre-eclampsia before 34 weeks of gestation (early-onset pre-eclampsia). For a false-positive rate of 11%, AIx-75 had a detection rate of 79% for all cases of pre-eclampsia and 88% for early-onset pre-eclampsia.

CONCLUSION

First-trimester arterial PWA can play a significant role in understanding the pathophysiology of pre-eclampsia and may play a role in early screening.

Modified myocardial performance index for evaluation of fetal cardiac function in pre-eclampsia

OBJECTIVE

To assess cardiac function by means of the modified myocardial performance index (Mod-MPI) in fetuses of pre-eclamptic mothers without intrauterine growth restriction and to compare this with values from normal controls.

METHODS

A cross-sectional study was conducted including a total of 72 fetuses at between 26 and 40 weeks' gestation. Forty fetuses of healthy mothers were assigned as the control group (Group I) while 15 fetuses of mildly pre-eclamptic mothers constituted Group II and 17 fetuses of severely pre-eclamptic mothers constituted Group III. Two-dimensional gray-scale and Doppler fetal echocardiography was used to exclude cardiac anomalies and calculate the Mod-MPI.

RESULTS

The mean+/-SD Mod-MPI values of Groups I, II and III were 0.43+/-0.045, 0.44+/-0.064 and 0.44+/-0.064, respectively (P=0.680). The mean aortic peak systolic velocity (PSV), the mean mitral valve early ventricular filling (E-wave) and active atrial filling (A-wave) peak velocities were significantly lower in fetuses of severely pre-eclamptic mothers than in fetuses of mildly pre-eclamptic mothers and control fetuses.

CONCLUSION

The fetal global myocardial function assessed by Mod-MPI does not seem to change in mild or severe pre-eclampsia. The lower mitral E-wave and A-wave peak velocities and the lower aortic PSV seem to reflect the increased cardiac afterload against which the fetal heart has to work, rather than systolic or diastolic cardiac dysfunction, in the fetuses of severely pre-eclamptic mothers.

Prediction of superimposed preeclampsia using uterine artery Doppler velocimetry in women with chronic hypertension

OBJECTIVE

To assess the role of uterine artery (UtA) Doppler to predict superimposed preeclampsia in women with chronic hypertension.

METHODS

In a cohort of 182 women with chronic hypertension, UtA Doppler studies were performed before 25 weeks (mean 19.7 +/- 2.1 weeks) and repeated later in pregnancy (mean 28.5 +/- 3.7 weeks).

RESULTS

The incidence of preeclampsia was 13% (24/182). Rates of preeclampsia increased with advancing gestation of abnormal UtA Doppler: 7% when UtA Doppler were normal at early exam, 18% when abnormal at early exam, and 28% when abnormal at late exam (Chi-square for trend: P < 0.001). The rate of preeclampsia among 40 women with abnormal early but normal late UtA Doppler was similar to that of women with normal findings at early exam (8 vs 7%; P = 1.00). Logistic regression analysis showed that the ability of UtA Doppler to predict preeclampsia was independent from other variables [Odds Ratio (OR) 7.1, 95% Confidence Interval (CI) 2.6-18.9). Receiver operating characteristic (ROC) curve identified a UtA value of 0.58 as the optimal threshold for the prediction of preeclampsia.

CONCLUSION

The later in pregnancy the abnormal UtA Doppler findings are observed, the greater the risk of preeclampsia. Normalization of UtA Doppler after 25 weeks reduces the risk of preeclampsia to 8%.

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.

Monitoring of fetal well-being: role of uterine artery Doppler

Doppler interrogation of the uterine arteries provides information on the physiologic transformation of the spiral arteries during pregnancy. Lack or suboptimal conversion of such arteries by the late second or third trimester of pregnancy is a strong indicator of increased risk for adverse pregnancy outcome, in particular, iatrogenic prematurity due to severe fetal growth restriction or preeclampsia. Uterine artery Doppler can thus play a role in the presence of medical conditions antedating pregnancy, which have greater risk of abnormal placentation, like chronic hypertension, to identify the subgroup with increased pregnancy complications and adverse outcome. In the presence of pregnancy complications related to inadequate placentation, such as fetal growth restriction or preeclampsia, uterine artery Doppler also plays a role, as abnormal findings signal increased severity of the disease and thus greater likelihood of unfavorable perinatal outcome.

An animal model of placental insufficiency-induced intrauterine growth restriction

Intrauterine growth restriction (IUGR), often associated with functional placental insufficiency, results in increased perinatal mortality and morbidity. For obvious reasons, many questions regarding the progression of IUGR pregnancies cannot be addressed experimentally in humans, predicating the use of animal models. Although no animal model fully recapitulates human pregnancy, the pregnant sheep has been used extensively to investigate maternal-fetal interactions. In sheep, surgical placement of catheters in both the maternal and fetal vasculature allows repeated sampling from nonanesthetized pregnancies. Considerable insight has been gained on placental oxygen and nutrient transfer and utilization from use of pregnant sheep, often confirmed in the human once appropriate technologies became available. This review will focus on one sheep model, used to examine the impact of placental insufficiency-induced IUGR on oxygen and nutrient transport and utilization.

Serial hemodynamic measurement in normal pregnancy, preeclampsia, and intrauterine growth restriction

OBJECTIVE

The study hypothesis was that hemodynamic measurements in conjunction with uterine artery Doppler could enable selection of women at risk for the development of preeclampsia or fetal growth restriction.

STUDY DESIGN

Systolic (SBP) and diastolic blood pressure, heart rate (RR), cardiac output (CO), total peripheral resistance (TPR), phase difference of SBP and RR interval were measured serially before, during, and after pregnancy. At 20 weeks, uterine artery Doppler measurement was performed. Outcome was classified as preeclampsia (PE) or gestational hypertension (GH) with or without fetal growth restriction (FGR), FGR without PE or GH, and normal pregnancy (NP). Differences between these groups were assessed by 1-way analysis of variance and discriminant analysis.

RESULTS

In early pregnancy, in comparison with NP (n = 28), PE/GH had a higher SBP and phase difference of SBP-RR interval. CO was higher in PE/GH without FGR (n = 5) but not PE/GH with FGR (n = 5). FGR, either with or without PE/GH (n = 4), was associated with higher TPR. Conjunction with uterine Doppler allowed selection of 93% of women with an abnormal outcome with a specificity of 100%.

CONCLUSION

The study supports our hypothesis that in early pregnancy, hemodynamic parameters differ from normal in women predisposed to develop preeclampsia or fetal growth restriction.

Total vascular resistance and left ventricular morphology as screening tools for complications in pregnancy

We evaluated the predictive value of elevated total vascular resistance on the outcome of pregnancy in normotensive high-risk primigravidas with bilateral notching of the uterine artery Doppler. A total of 526 high-risk primigravidas referred to the obstetrics outpatient clinic of Tor Vergata University with bilateral notching of the uterine artery at 20 to 22 weeks' gestation were submitted to a maternal echocardiographic examination and uterine artery Doppler evaluation at 24 weeks' gestation. Blood pressure was recorded at the time of the examination, total vascular resistance was calculated, and the geometric pattern of the left ventricle was assessed. Patients were followed until the end of pregnancy to detect fetal/maternal adverse outcomes (gestational hypertension, preeclampsia, abruptio placentae, fetal growth restriction, perinatal death, etc). A total of 111 of the 526 pregnancies showed a bilateral notch at 24 weeks' gestation, and 97 had an adverse outcome (18.44%). The best independent predictor for maternal and fetal complications was total vascular resistance (odds ratio: 91.25; 95% CI: 39.64 to 210.05; P<0.001). The cutoff value was 1400 dynes x s x cm(-5), with a sensitivity and a specificity of 89% and 94%, respectively. A high relative wall thickness of the left ventricle (>0.37; odds ratio: 2.47; 95% CI: 1.12 to 5.44) and a hypertrophized ventricle (left ventricular mass >130 g; odds ratio: 2.52; 95% CI: 1.12 to 5.64) were also independent predictors (P<0.05). Echocardiography might identify at 24 weeks' gestation patients who subsequently develop maternal and fetal complications through the assessment of maternal hemodynamics and left ventricular geometry.

The pregnant sheep as a model for human pregnancy

Successful outcome of human pregnancy not only impacts the quality of infant life and well-being, but considerable evidence now suggests that what happens during fetal development may well impact health and well-being into adulthood. Consequently, a thorough understanding of the developmental events that occur between conception and delivery is needed. For obvious ethical reasons, many of the questions remaining about the progression of human pregnancy cannot be answered directly, necessitating the use of appropriate animal models. A variety of animal models exist for the study of both normal and compromised pregnancies, including laboratory rodents, non-human primates and domestic ruminants. While all of these animal models have merit, most suffer from the inability to repetitively sample from both the maternal and fetal side of the placenta, limiting their usefulness in the study of placental or fetal physiology under non-stressed in vivo conditions. No animal model truly recapitulates human pregnancy, yet the pregnant sheep has been used extensively to investigate maternal-fetal interactions. This is due in part to the ability to surgically place and maintain catheters in both the maternal and fetal vasculature, allowing repeated sampling from non-anesthetized pregnancies. Considerable insight has been gained on placental oxygen and nutrient transfer and utilization from use of pregnant sheep. These findings were often confirmed in human pregnancies once appropriate technologies became available. The purpose of this review is to provide an overview of human and sheep pregnancy, with emphasis placed on placental development and function as an organ of nutrient transfer.

The 20-week scan: beyond biometry and anatomy

The "definition" of the 20-week scan should now be significantly expanded. Traditionally, the objectives of such an examination were the determination of gestational age, the detection of congenital morphologic defects, and the cursory evaluation of placental location and amniotic fluid volume. Remarkable progress has been made in intervening years. Great technical strides have been accomplished in sonographic resolution. Along with proper training of personnel improved diagnostic accuracy for anomaly detection can be anticipated. It is likely that the more recent applications of ultrasound such as uterine artery Doppler velocimetry and cervical status evaluation could equal or eclipse the significance and clinical benefits of anomaly detection.

Uterine artery Doppler velocimetry at 11-14 weeks in singleton pregnancies conceived by assisted reproductive technology

OBJECTIVE

Singleton pregnancies resulting from assisted reproductive technologies (ART) have an increased risk of preterm delivery, pre-eclampsia and intrauterine growth restriction. The aim of the present study was to determine whether first-trimester trophoblastic invasion, as assessed by uterine artery Doppler velocimetry, is different in singleton pregnancies resulting from ART compared to those conceived naturally.

METHODS

Case-control study on 31 singleton ART pregnancies (26 in-vitro fertilization-embryo transfer, five intracytoplasmic sperm injection) and 62 matched pregnancies conceived spontaneously. Doppler velocimetry was performed at 11-14 weeks of gestation.

RESULTS

The mean resistance index (coefficient of variation) was 0.70 (17%) and 0.70 (18%) in ART and controls, respectively (P = 0.92). The corresponding values for mean pulsatility index were 1.40 (44%) and 1.47 (44%) in ART and controls, respectively (P = 0.58). Pregnancies with no, unilateral or bilateral diastolic notches were 48%, 26%, 26% and 36%, 37%, 27%, in ART and controls, respectively (P = 0.43).

CONCLUSION

There are no differences in uterine artery Doppler indices between pregnancies obtained by invasive ART and naturally conceived matched controls. This finding suggests that there is no major difference in trophoblastic invasion of the maternal spiral arteries between ART and spontaneous pregnancies.

Circulating angiogenic factors and abnormal uterine artery Doppler velocimetry in the second trimester

OBJECTIVE

Circulating angiogenic growth factors (such as vascular endothelial growth factor [VEGF] and placental growth factor [PlGF]) and their interaction may be associated with vascular remodeling of spiral arteries in normal pregnancy. Soluble Flt-1, an antagonist of both VEGF and PlGF, has been shown to be increased, while PlGF is decreased in women prior to the onset of preeclampsia. The purpose of this study was to compare maternal soluble Flt-1 and PlGF levels in the second trimester with a marker of abnormal placentation, abnormal uterine artery Doppler (UAD).

METHOD

A prospective cohort of women, 16 to 24 weeks estimated gestational age (EGA), with singleton pregnancies, underwent UAD and phlebotomy. Maternal soluble Flt-1 and free PlGF were measured by ELISA in samples from women with abnormal UAD with a group, controlled for EGA, with normal UAD. Mann-Whitney Rank-Sum test was used to compare maternal serum levels of both soluble Flt-1 and PlGF between women with abnormal uterine artery Doppler versus women with normal uterine artery Doppler.

RESULTS

Of the 222 study subjects enrolled, 34 (15%) had abnormal UAD. The mean EGA at enrollment of subjects in each group was 18 weeks. There was no difference in PlGF between subjects with abnormal UAD (median, 191 pg/mL; range, 187 to 337 pg/mL) versus controls (median, 171 pg/mL; range, 169 to 289 pg/mL) (p = 0.59) or soluble Flt-1 (median, 780 pg/mL; range, 280 to 3200 pg/mL) or between subjects with abnormal UAD versus controls (median, 720 pg/mL; range, 220 to 1980 pg/mL) (p = 0.36).

CONCLUSION

Concentrations of maternal soluble Flt-1 and free PlGF in the second trimester do not appear to be altered in women with abnormal UAD. This suggests that these biochemical markers are independent of the increased placental resistance seen with abnormal uterine artery Doppler.

Sequential changes in uterine artery blood flow pattern between the first and second trimesters of gestation in relation to pregnancy outcome

OBJECTIVE

To describe sequential changes in uterine artery waveform between the first and second trimesters of gestation and to analyze their association with the subsequent risk of hypertensive disorders and fetal growth restriction (IUGR).

METHODS

Sequential uterine artery Doppler recordings were obtained in a final cohort of 870 singleton pregnancies over two gestational age intervals: 11-14 weeks and 19-22 weeks. The left and right uterine arteries were examined by color and pulsed Doppler and the mean pulsatility index (PI) as well as the presence of a bilateral protodiastolic notch were recorded during both intervals. Pregnancies were followed for occurrence of hypertensive disorders and IUGR.

RESULTS

Mean uterine artery PI showed a significant linear decrease within each of the two intervals considered, while the prevalence of a bilateral notch showed decreasing values only throughout 11-14 weeks of gestation. Sixty-four (7.3%) pregnancies developed a hypertensive disorder and/or IUGR, including three (0.34%) cases of gestational hypertension, 24 cases of pre-eclampsia (2.75%) and 37 (4.25%) of IUGR. Compared with pregnancies with a normal outcome, complicated pregnancies showed a significantly higher prevalence of a bilateral notch and a higher mean PI in each of the two intervals studied. Compared with normal pregnancies, complicated pregnancies had a significantly higher persistence of a bilateral notch (30% vs. 8%), a higher proportion of women with an abnormal first-trimester uterine artery PI shifting to normal in the second trimester (14% vs. 4%) and a higher incidence of a normal first-trimester mean PI that shifted to abnormal in the second trimester (13% vs. 4%). Persistence of an abnormal mean PI from the first to the second trimester identified the group with the greatest risk for adverse perinatal outcome (OR, 10.7; 95% CI, 3.7-30.9). In addition, women in whom the uterine artery mean PI shifted from abnormal to normal between the two trimesters and women in whom the reverse shift occurred showed a similar intermediate risk (OR, 5; 95% CI, 2.1-10.6), comparable to that in women with persistence of a bilateral notch (OR, 5.6; 95% CI, 2.9-10.7).

CONCLUSIONS

The sequence of changes in uterine flow between the first and second trimesters correlates with the subsequent development of hypertensive disorders and IUGR. Women with a persistent abnormal mean PI represent the group with the greatest risk for adverse perinatal outcome.