Arterial and venous Doppler velocimetry in the severely growth-restricted fetus and associations with adverse perinatal outcome

Obstetric ultrasound: where are we and where are we going?

Diagnostic ultrasound (DUS) is, arguably, the most common technique used in obstetrical practice. From A mode, first described by Ian Donald for gynecology in the late 1950s, to B mode in the 1970s, real-time and gray-scale in the early 1980s, Doppler a little later, sophisticated color Doppler in the 1990s and three dimensional/four-dimensional ultrasound in the 2000s, DUS has not ceased to be closely associated with the practice of obstetrics. The latest innovation is the use of artificial intelligence which will, undoubtedly, take an increasing role in all aspects of our lives, including medicine and, specifically, obstetric ultrasound. In addition, in the future, new visualization methods may be developed, training methods expanded, and workflow and ergonomics improved.

Prenatally diagnosed congenital hemangioma with elevated middle cerebral artery peak systolic velocity mimicking the Kasabach-Merritt phenomenon: A case report

Congenital hemangioma is a rare vascular tumor that develops prenatally, and a large congenital hemangioma may be accompanied by the Kasabach-Merritt phenomenon. We present a case of prenatally diagnosed fetal congenital hemangioma through ultrasound and maternal anti-Jr(a) antibody alloimmunization with elevated middle cerebral artery peak systolic velocity. To investigate fetal anemia and hemostatic condition, we performed percutaneous umbilical blood sampling, which revealed no symptom of either Kasabach-Merritt phenomenon or sensitization to anti-Jr(a) antibody. Consequently, pregnancy could be continued without further intervention. After birth, congenital hemangioma was found on the infant's left thigh, and Kasabach-Merritt phenomenon was not shown. Percutaneous umbilical blood sampling could provide precise information prenatally in case of congenital hemangioma with maternal alloimmunization.

Assessment of the Fetal Cerebral Artery: Importance of Doppler Preset Settings

OBJECTIVES

The Doppler assessment of the middle cerebral artery (MCA) has a central role in the monitoring of high-risk pregnancies. The objective of this study was to investigate the importance of Doppler preset settings for measurement of the peak systolic velocity (PSV) and pulsatility index (PI) of the MCA.

METHODS

The PI and PSV of the MCA were determined prospectively in 350 healthy fetuses between 19 and 42 weeks of pregnancy. The first measurement of the MCA (MCA.S) was performed with the conventional settings and the second (MCA.O) with an optimized setting of the maximum achievable frame rate. For the MCA.O measurement, the width of the B-mode image and the color Doppler window were adjusted as narrowly as possible. In addition, the MCA was shown in optimized high-definition zoom. Resulting values were compared with commonly used reference values.

RESULTS

The PSV and PI values and frame rates of the MCA.O setting were noticeably greater than those of the MCA.S setting (P < .001 for all). For both settings, the PSV and PI values were increased compared to common reference values.

CONCLUSIONS

The assessment of the MCA with the optimized Doppler default setting yielded increased PSV and PI values compared to the commonly used measurement technique. Moreover, the resulting median curves differed from the established median reference curves. Therefore, an updated standardization for measuring the MCA should be set out, and current reference values should be adjusted.

Risk of fetal death in growth-restricted fetuses with umbilical and/or ductus venosus absent or reversed end-diastolic velocities before 34 weeks of gestation: a systematic review and meta-analysis

OBJECTIVE

The objective of the study was to establish the risk of fetal death in early-onset growth-restricted fetuses with absent or reversed end-diastolic velocities in the umbilical artery or ductus venosus.

DATA SOURCES

A systematic search was performed to identify relevant studies published in English, Spanish, French, Italian, or German using the databases PubMed, ISI Web of Science, and SCOPUS, without publication time restrictions.

STUDY ELIGIBILITY CRITERIA

The study criteria included observational cohort studies and randomized controlled trials of early-onset growth-restricted fetuses (diagnosed before 34 weeks of gestation), with information on the rate of fetal death occurring before 34 weeks of gestation and absent or reversed end-diastolic velocities in the umbilical artery and/or ductus venosus.

STUDY APPRAISAL AND SYNTHESIS METHODS

For quality assessment, 2 reviewers independently assessed the risk of bias using the Newcastle-Ottawa Scale for observational studies and the Cochrane Collaboration's tool for randomized trials. For the meta-analysis, odds ratio for both fixed and random-effects models (weighting by inverse of variance) were used. Heterogeneity between studies was assessed using tau², χ2 (Cochrane Q), and I² statistics. Publication bias was assessed by a funnel plot for meta-analyses and quantified by the Egger method.

RESULTS

A total of 31 studies were included in this meta-analysis. The odds ratios for fetal death (random-effects models) were 3.59 (95% confidence interval, 2.3-5.6), 7.27 (95% confidence interval, 4.6-11.4), and 11.6 (95% confidence interval, 6.3-19.7) for growth-restricted fetuses with umbilical artery absent end-diastolic velocities, umbilical artery reversed end-diastolic velocities, and ductus venosus absent or reversed end-diastolic velocities, respectively. There was no substantial heterogeneity among studies for any of the analyses.

CONCLUSION

Early-onset growth-restricted fetuses with either umbilical artery or ductus venosus absent or reserved end-diastolic velocities are at a substantially increased risk for fetal death.

Postnatal changes in cerebral blood flow velocity in term intra-uterine growth-restricted neonates

BACKGROUND

Intra-uterine growth-restricted (IUGR) fetuses are prone to hypoxic changes in the brain and neurodevelopmental sequelae in later life. Chronic hypoxaemia may also lead to polycythaemia in the fetal and neonatal period.

AIM

To evaluate venous haematocrit and cerebral blood flow velocity (CBFV) in term IUGR neonates in the immediate postnatal period.

METHODS

This was a prospective observational study of 54 clinically healthy term IUGR neonates as cases and 50 term, appropriate-for-gestational-age (AGA), healthy neonates as controls. IUGR was defined as birthweight <10th per centile for gestational age. Neonates with perinatal asphyxia, sepsis and other systemic diseases were excluded. Resistance index (RI), pulsatility index (PI), peak systolic velocity (PSV) and vascular diameter were measured in the internal carotid, vertebral and middle cerebral arteries by transcranial colour Doppler ultrasound between 48 and 72 hours of life, along with the estimation of venous haematocrit. Neonates were observed for development of any complications until discharge and followed up clinically and radiologically for a minimum 6 months.

RESULTS

Significantly higher resistance (RI and PI) and lower PSV was recorded in all the cerebral arteries of the IUGR than the AGA group whereas no difference was observed in vascular diameters. Mean haematocrit was significantly higher in the IUGR than in the AGA group [55·7 (4·22) vs 45·1 (2·79) g/dl]. Haematocrit was positively correlated with RI and PI, and negatively correlated with PSV. After discharge, three infants in the IUGR group showed hypertonia and delayed developmental milestones along with hypoxic changes in MRI of the brain.

CONCLUSIONS

Compared with their AGA counterparts, higher venous haematocrit and lower CBFV were observed in clinically healthy, term IUGR neonates during the early neonatal period. Delayed developmental milestones and hypoxic changes were detected by MRI in three infants. Since the study was limited by its sample size, larger studies are required to document the clinical significance of decreased CBFV and its usefulness as a marker of poor prognosis for future neurodevelopment.

Doppler assessment of the fetus with intrauterine growth restriction

OBJECTIVE

We sought to provide evidence-based guidelines for utilization of Doppler studies for fetuses with intrauterine growth restriction (IUGR).

METHODS

Relevant documents were identified using PubMed (US National Library of Medicine, 1983 through 2011) publications, written in English, which describe the peripartum outcomes of IUGR according to Doppler assessment of umbilical arterial, middle cerebral artery, and ductus venosus. Additionally, the Cochrane Library, organizational guidelines, and studies identified through review of the above were utilized to identify relevant articles. Consistent with US Preventive Task Force suggestions, references were evaluated for quality based on the highest level of evidence, and recommendations were graded.

RESULTS AND RECOMMENDATIONS

Summary of randomized and quasirandomized studies indicates that, among high-risk pregnancies with suspected IUGR, the use of umbilical arterial Doppler assessment significantly decreases the likelihood of labor induction, cesarean delivery, and perinatal deaths (1.2% vs 1.7%; relative risk, 0.71; 95% confidence interval, 0.52-0.98). Antepartum surveillance with Doppler of the umbilical artery should be started when the fetus is viable and IUGR is suspected. Although Doppler studies of the ductus venous, middle cerebral artery, and other vessels have some prognostic value for IUGR fetuses, currently there is a lack of randomized trials showing benefit. Thus, Doppler studies of vessels other than the umbilical artery, as part of assessment of fetal well-being in pregnancies complicated by IUGR, should be reserved for research protocols.

Early adverse perinatal complications in preterm growth-restricted fetuses

INTRODUCTION

Growth-restricted fetuses are at increased risk of adverse perinatal outcome when compared to their normally grown counterparts. The additional risks associated with growth restriction in preterm fetuses are not well quantified, and this meta-analysis serves to address this uncertainty.

MATERIALS AND METHODS

This is a meta-analysis and meta-regression of all relevant studies published since 1997 investigating perinatal outcome in preterm growth-restricted fetuses.

RESULTS

Growth-restricted fetuses across all gestational ages were found to be at significant risk of having low Apgar scores at 5 min, sepsis, intracranial haemorrhage, intrauterine and neonatal death, necrotising enterocolitis and respiratory complications. Although this risk reduced as gestation increased, it remained amplified in growth-restricted fetuses when compared to normally grown fetuses.

CONCLUSION

This large meta-analysis for the first time quantifies the additional perinatal risks associated with preterm fetal growth restriction and may help counsel parents about the complications these fetuses face following birth.

The importance of venous Doppler velocimetry for evaluation of intrauterine growth restriction

The management of growth-restricted fetuses requires accurate diagnosis to optimize the timing of delivery. Doppler velocimetry is the only noninvasive method for assessing the fetoplacental hemodynamic status. This review will give a critical overview of the current knowledge on fetal venous blood flow in pregnancies complicated by in-trauterine growth-restricted fetuses. Adaptation of the circulation in intrauterine growth-restricted fetuses is described. Normal and abnormal venous Doppler waveforms are presented. Correlations of abnormal waveforms with the presence of acidemia and perinatal outcomes are emphasized. Limitations of venous Doppler velocimetry for optimizing the time for delivery and the perinatal outcome are also presented.

Dopplervelocimetria fetoplacentária em gestantes hipertensas e resultados perinatais segundo a idade gestacional

OBJETIVO: Avaliar índices de pulsatilidade das artérias umbilical (IPAU) e cerebral média (IPACM) e relação do índice de pulsatilidade umbilico-cerebral (IPAU/IPACM) em fetos de gestantes hipertensas e presença de resultados perinatais adversos. MATERIAIS E MÉTODOS: Analisamos IPAU, IPACM e IPAU/IPACM de 289 fetos de gestantes hipertensas quanto à previsão dos resultados perinatais adversos. Os resultados foram comparados sem e com ajuste pela idade gestacional. RESULTADOS: O índice de Apgar < 7 no 5º minuto foi associado com resultados alterados após o ajuste por idade gestacional. O risco para recém-nascidos pequenos para a idade gestacional aumentou em três vezes após o ajuste, com significância estatística em todos os parâmetros do Doppler. Na síndrome da hipóxia neonatal o aumento do risco ajustado pela idade gestacional foi estatisticamente significante no IPAU e IPAU/IPACM. Não houve aumento no risco de síndrome do desconforto respiratório na análise ajustada. A mortalidade perinatal e o IPAU alterado apresentaram um risco três vezes maior e foram estatisticamente significantes após o ajuste. CONCLUSÃO: Em gestantes hipertensas, o IPAU apresentou melhor correlação com os resultados perinatais do que o IPACM ou relação IPAU/IPACM. O risco de resultados adversos deve considerar a idade gestacional.

Systematic review and meta-analysis of the test accuracy of ductus venosus Doppler to predict compromise of fetal/neonatal wellbeing in high risk pregnancies with placental insufficiency

OBJECTIVE

To evaluate the test accuracy of ductus venosus Doppler for prediction of compromise of fetal/neonatal wellbeing.

STUDY DESIGN

The search strategy employed searching of electronic databases (Medline, Embase, Cochrane library, Medion) from inception to May 2009, hand searching of journal and reference lists, contact with experts. Two reviewers independently selected articles in which the results of ductus venosus Doppler were associated with the occurrence of compromise of fetal/neonatal wellbeing. There were no language restrictions applied. Data were extracted on study characteristics, quality and results to construct 2 x 2 tables. Likelihood ratios for positive and negative test results, sensitivity, specificity and their 95% confidence intervals were generated for the different indices and thresholds.

RESULTS

Eighteen studies, testing 2267 fetuses met the selection criteria, all performed in a high risk population with placental insufficiency in second/third trimester. Meta-analysis showed moderate predictive accuracy. The best result was for the prediction of perinatal mortality, positive likelihood ratio 4.21 (95% CI 1.98-8.96) and negative likelihood ratio 0.43 (95% CI 0.30-0.61). For prediction of adverse perinatal outcome the results were positive likelihood ratio 3.15 (95% CI 2.19-4.54) and negative likelihood ratio 0.49 (95% CI 0.40-0.59).

CONCLUSION

Abnormal ductus venosus Doppler showed moderate predictive accuracy for compromise of fetal/neonatal wellbeing overall and perinatal mortality in high risk pregnancies with placental insufficiency.

ADEPT - Abnormal Doppler Enteral Prescription Trial

BACKGROUND

Pregnancies complicated by abnormal umbilical artery Doppler blood flow patterns often result in the baby being born both preterm and growth-restricted. These babies are at high risk of milk intolerance and necrotising enterocolitis, as well as post-natal growth failure, and there is no clinical consensus about how best to feed them. Policies of both early milk feeding and late milk feeding are widely used. This randomised controlled trial aims to determine whether a policy of early initiation of milk feeds is beneficial compared with late initiation. Optimising neonatal feeding for this group of babies may have long-term health implications and if either of these policies is shown to be beneficial it can be immediately adopted into clinical practice.

METHODS AND DESIGN

Babies with gestational age below 35 weeks, and with birth weight below 10th centile for gestational age, will be randomly allocated to an "early" or "late" enteral feeding regimen, commencing milk feeds on day 2 and day 6 after birth, respectively. Feeds will be gradually increased over 9-13 days (depending on gestational age) using a schedule derived from those used in hospitals in the Eastern and South Western Regions of England, based on surveys of feeding practice. Primary outcome measures are time to establish full enteral feeding and necrotising enterocolitis; secondary outcomes include sepsis and growth. The target sample size is 400 babies. This sample size is large enough to detect a clinically meaningful difference of 3 days in time to establish full enteral feeds between the two feeding policies, with 90% power and a 5% 2-sided significance level. Initial recruitment period was 24 months, subsequently extended to 38 months.

DISCUSSION

There is limited evidence from randomised controlled trials on which to base decisions regarding feeding policy in high risk preterm infants. This multicentre trial will help to guide clinical practice and may also provide pointers for future research.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN: 87351483.

Respiratory outcome in preterm small for gestational age fetuses with or without abnormal umbilical artery Doppler and/or maternal hypertension

OBJECTIVE

To study respiratory outcome in preterm small for gestational age (SGA) fetuses with or without signs of intrauterine growth restriction due to placental insufficiency, and with or without maternal hypertension.

METHODS

This was a retrospective study of 187 neonates with birth weight <10(th) percentile and gestational age <34 weeks. Results from umbilical artery Doppler velocimetry were used to identify the abnormal Doppler subgroup.

RESULTS

No significant difference in respiratory outcome between SGA fetuses with normal (SGA-N) or abnormal (SGA-A) umbilical artery Doppler examination was found. Within the SGA-A group, the respiratory distress syndrome (RDS) incidence (OR 5.6, 95% CI 1.7-18.3), RDS grade (OR 6.7, 95% CI 1.2-38.5), and need for surfactant (OR 5.3, 95% CI 1.1-24.4) were higher in infants of women with hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome as compared to those of normotensive mothers.

CONCLUSIONS

Lung maturation is not accelerated with placental insufficiency. SGA-A fetuses of mothers with HELLP syndrome have a significantly poorer respiratory outcome than those with healthy mothers. Possibly, fetuses of mothers with HELLP syndrome are subjected to 'oxidative stress' causing lung damage rather than lung maturation.

Antenatal umbilical Doppler abnormalities: an independent risk factor for early onset neonatal necrotizing enterocolitis in premature infants

BACKGROUND

Necrotizing enterocolitis (NEC) is the most common gastrointestinal (GI) emergency seen in neonatal units. Many factors have been considered as potentially important aetiologically, including gut ischaemia, sepsis and feeding. However, evidence remains equivocal.

OBJECTIVE

This study investigated whether preterm babies born to mothers with abnormal antenatal umbilical Dopplers (absent or reversed end diastolic flow--AREDF), that is exposed to antenatal gut ischaemia, are at an identical risk of developing NEC early in life, compared to babies born to mothers with normal Dopplers.

METHODS

All preterm (<or=32+6 week gestation) babies with no congenital anomaly, born to mothers resident in the county of Leicestershire in United Kingdom in 2001 and 2002 were identified using the Trent Neonatal Survey (TNS). Clinical data including the presence and severity of any NEC were extracted from the notes.

RESULTS

Two hundred forty-three preterm babies who met the criteria were identified during the period. Babies in whom umbilical Dopplers were not available and babies that died in the first 48 h were excluded. Complete data was thus available for 206 of these babies. A strong relation between AREDF and subsequent development of NEC was noted in these babies (OR: 5.88, 95% CI: 2.41 to 14.34, p<0.0001). This association still held after adjustment for gestational age at birth (OR: 7.64, 95% CI: 2.96 to 19.70, p<0.0001) and after adjustment for birthweight for gestational age z-score (OR: 6.72, 95% CI: 2.23 to 20.25, p=0.0007).

CONCLUSIONS

This study, based on a neonatal cohort, indicates that AREDF is an important independent risk factor for the production of NEC.

Diagnosis and management of fetal growth restriction: the role of fetal therapy

Fetal growth restriction remains a major cause of perinatal morbidity and mortality in modern obstetric practice. Placental insufficiency is the most common association, but is often a diagnosis of exclusion. Currently, no treatment can ameliorate or reverse established growth restriction: maximising gestational age and judicious timing of steroid administration and delivery are the primary tasks for the obstetrician. Although comprehensive surveillance of the preterm fetus now includes ductus venosus Doppler studies, its effectiveness in timing delivery has yet to be confirmed in randomised controlled trials. More basic research on the regulation of fetal growth is needed before specific therapies for established growth restriction can be developed.

Intrauterine growth restriction: how to manage and when to deliver

Intrauterine growth restriction secondary to placental insufficiency is a major cause of perinatal morbidity and mortality in the United States. Once intrauterine growth restriction is identified, obstetrical management is focused on assuring safety while the fetus continues to mature within a potentially hostile intrauterine environment. In the United States, the approach to management and delivery of the premature growth-restricted fetus is often based on serial biophysical profile evaluations, whereas in Europe it is usually based on the results of cardiotocography. However, there is no single test that seems superior to the other available tests for timing the delivery of the growth-restricted fetus. Therefore, the decision to deliver a fetus, especially at <32 weeks, remains mostly on the basis of empirical management.

Gestational age at delivery and Doppler waveforms in very preterm intrauterine growth-restricted fetuses as predictors of perinatal mortality

OBJECTIVE

The aim of this study was to compare gestational age at delivery and the performance of middle cerebral artery (MCA), ductus venosus (DV), and umbilical artery Doppler parameters in the prediction of perinatal mortality and morbidity in intrauterine growth-restricted (IUGR) fetuses delivered at 32 weeks or earlier.

METHODS

The study population consisted of 41 patients with IUGR fetuses. Delivery occurred for maternal or fetal indications. Two-tailed chi(2) and Fisher exact tests, an independent t test, and logistic regression were used for the analysis. P < .05 was considered statistically significant.

RESULTS

Gestational age at delivery ranged between 23.1 and 32 weeks (median, 27.6 weeks). There were 17 perinatal deaths. Ninety-four percent of the perinatal deaths occurred when the fetuses were delivered before 29 weeks. No fetus survived when delivered before 25 weeks. Two parameters predicted the perinatal mortality: gestational age at delivery (odds ratio, 0.52; 95% confidence interval, 0.31-0.88) and the combination of abnormal MCA peak systolic velocity + DV reversed flow (odds ratio, 10.2; 95% confidence interval, 1.8-57). For each week of pregnancy, there was a reduction in perinatal mortality of 48%. No Doppler parameters were significantly associated with perinatal morbidity.

CONCLUSIONS

Gestational age at delivery and the combination of abnormal MCA peak systolic velocity + DV reversed flow in very preterm IUGR fetuses were the best parameters in predicting perinatal mortality. The decreased perinatal mortality that is found for each week IUGR fetuses remain in utero should be taken into account when a decision to deliver an IUGR fetus before 30 weeks is made.

Apport du doppler du canal d'Arantius dans la prise en charge des retards de croissance intra-utérin d'origine vasculaire

Intra uterine growth retardation is a major cause of perinatal morbidity and mortality. These are due to prolonged intra uterine hypoxia and complications from subsequent induced prematurity. Fetal arterial doppler measurements, and more recently venous Doppler measurements, help choosing the ideal moment for delivering these fragile fetuses. Nevertheless, venous doppler measurements should be combined to other monitoring tools, used longitudinally and only when very preterm birth is expected.

Middle cerebral artery peak systolic velocity: a new Doppler parameter in the assessment of growth-restricted fetuses

OBJECTIVE

The aims of this study were to determine if there is a relationship between middle cerebral artery (MCA) peak systolic velocity (PSV) and perinatal mortality in preterm intrauterine growth-restricted (IUGR) fetuses, to compare the performance of MCA pulsatility index (PI), MCA-PSV and umbilical artery (UA) absent/reversed end-diastolic velocity (ARED) in predicting perinatal mortality, to determine the longitudinal changes that occur in MCA-PI and MCA-PSV in these fetuses, and to test the hypothesis that MCA-PSV can provide additional information on the prognosis of hypoxemic IUGR fetuses.

METHODS

This was a retrospective cross-sectional study of 30 IUGR fetuses (estimated fetal weight < 3(rd) percentile; UA-PI > 95% CI) in which the last MCA-PI, MCA-PSV and UA values were obtained within 8 days before delivery or fetal demise. Among the 30 fetuses, there were 10 in which at least three consecutive measurements were performed before delivery and these were used for a longitudinal study. MCA-PSV and MCA-PI values were plotted against normal reference ranges and were considered abnormal when they were above the MCA-PSV or below the MCA-PI reference ranges.

RESULTS

Gestational age at delivery ranged between 23 + 1 and 32 + 5 (median, 27 + 6) gestational weeks. Birth weight ranged from 282 to 1440 (median, 540) g. There were 11 perinatal deaths. Forward stepwise logistic regression indicated that MCA-PSV was the best parameter in the prediction of perinatal mortality (odds ratio, 14; 95% CI, 1.4-130; P < 0.05) (Nagerlke R(2) = 31). In the 10 fetuses studied longitudinally, an abnormal MCA-PI preceded the appearance of an abnormal MCA-PSV. In these fetuses, the MCA-PSV consistently showed an initial increase in velocity; before demise or the appearance of a non-reassuring test in seven fetuses, there was a decrease in blood velocity. The MCA-PI presented an inconsistent pattern.

CONCLUSIONS

In IUGR fetuses, the trends of the MCA-PI and MCA-PSV provide more clinical information than does one single measurement. A high MCA-PSV predicts perinatal mortality better than does a low MCA-PI. We propose that MCA-PSV might be valuable in the clinical assessment of IUGR fetuses that have abnormal UA Doppler.

Antenatal Doppler measurements and early brain injury in very low birth weight infants

OBJECTIVE

To determine the correlation between fetoplacental blood flow and brain injury and volumes in very low birth weight (VLBW) infants.

STUDY DESIGN

Antenatal blood flow from the umbilical artery (UA), middle cerebral artery (MCA), and descending aorta was determined in 70 VLBW infants. The directions of the total diastolic flow of the aortic isthmus and the end-diastolic flow of ductus venosus also were measured. Serial brain ultrasound examinations and MRI at term were performed to assess brain abnormalities. On the basis of brain imaging findings, the newborn infants were classified as normal (n = 14), intermediate brain pathology (n = 31), and major pathology (n = 25) groups.

RESULTS

Abnormalities in fetoplacental blood flow were not related to anatomic brain lesions. However, an abnormal UA/MCA pulsatility index ratio was associated with reduced total brain volume (mean, 360 mL; SD, 32.5 mL) and reduced cerebral volume (344 mL; SD, 28.4 mL) compared with infants with normal UA/MCA pulsatility index ratio (mean, 405 mL; SD, 51.3 mL, P = .01, and mean, 368 mL; SD, 52.3 mL, P = .012), respectively.

CONCLUSIONS

Redistribution of fetal blood flow in VLBW infants is associated with reduced brain volume at term age. Neurodevelopmental follow-up of this cohort will clarify the significance of these blood flow changes on development.

[Screening and timing for the delivery of fetuses with intrauterine growth restriction of vascular origin]

The prenatal management of fetuses with intrauterine growth restriction (IUGR) has been a matter of perpetual evolving in obstetrics and has been the topic of numerous studies. The management of IUGR fetuses is currently available in tertiary centres using fetal heart monitoring, short term variability, or doppler investigation of the umbilical artery, ductus venosus and middle cerebral artery. The aim of the prenatal management is to detect anomalies that may predict severe fetal hypoxemia. On the other hand, any efforts should focus on the possibility to delay the time for delivery as gestational age at delivery together with birth weight appear to be essential parameters of the postnatal outcome.

Ultrasound and fetal diagnosis

PURPOSE OF REVIEW

The purpose of this review is to highlight publications from the last year that have advanced the use of ultrasound in obstetrics.

RECENT FINDINGS

Anatomic examination of the fetus in the first trimester has been emphasized because it allows for early diagnosis of many conditions. The prevalence of absent nasal bone, a marker for trisomy 21, in euploid fetuses depends on ethnicity. Nasal bone hypoplasia is another marker for Down syndrome. Studies on genetic screening in the first trimester have involved various serum analytes, adjustments in timing and calculations, use in multiple gestations, and the association of extreme measurements with adverse outcomes. A first-trimester integrated screening approach, which incorporates nuchal translucency, nasal bone, crown-rump length, pregnancy-associated plasma protein-A, and free beta-human chorionic gonadotropin, has the potential to maximize detection rates of Down syndrome and trisomy 18 and minimizes the screen-positive rate. The value of combining first and second-trimester results in sequential, contingent, or integrated screening protocols has been assessed. Isolated mild ventriculomegaly (10-12 mm) may prove to be a normal variant, and the role of 'soft' ultrasound markers in genetic counseling continues to be debated. Anomaly or high-risk status detection in the second trimester has been enhanced by the use of Doppler, 3D/4D ultrasound, and magnetic resonance imaging.

SUMMARY

Imaging techniques have been critical in the development of screening methods for Down syndrome or trisomy 18 and for euploid fetuses at high risk for adverse outcomes.

Doppler, Cardiotocography, and Biophysical Profile Changes in Growth-Restricted Fetuses

OBJECTIVE

To assess from diagnosis to delivery the Doppler studies of the umbilical artery, middle cerebral artery, umbilical vein, ductus venosus, and amniotic fluid index of fetuses with idiopathic growth restriction.

METHODS

A total of 145 singleton growth-restricted fetuses with abnormal umbilical artery pulsatility indexes were studied. Cesarean delivery was performed because of abnormal biophysical profile or nonreassuring fetal heart rate pattern.

RESULTS

There were 4 fetal and 50 neonatal deaths. Two growth-restricted groups were identified: Group A (n = 44) included fetuses in whom all measures became abnormal preceding an abnormal biophysical profile or nonreassuring nonstress test. Group B (n = 101) included fetuses in whom 1 or more measures were normal at the time of cesarean delivery. There was no statistically significant difference in perinatal morbidity and mortality between the 2 groups. Neonatal death was increased in fetuses with umbilical artery reversed flow (odds ratio 2.34, 95% confidence interval 1.16-4.73; P < .05) and ductus venosus reversed flow (odds ratio 4.18, 95% confidence interval 2.01-8.69; P < .05). A significant correlation was also found between low birth weight and adverse perinatal outcome.

CONCLUSION

In fetuses with idiopathic growth restriction, 1) low birth weight, 2) umbilical artery reversed flow, and 3) ductus venosus absent or reversed flow are associated with an increased perinatal morbidity and mortality.

Feeding growth restricted preterm infants with abnormal antenatal Doppler results

Absence or reversal of end diastolic flow (AREDF) in the umbilical artery is associated with poor outcome, and elective premature delivery is common. Feeding these infants is a challenge. They often have poor tolerance of enteral feeding, and necrotising enterocolitis may develop. This review explores current practice to see if there is evidence on which to base guidelines. The incidence of necrotising enterocolitis is increased in infants with fetal AREDF, especially when complicated by fetal growth restriction. Abnormalities of splanchnic blood flow persist postnatally, with some recovery during the first week of life, providing justification for a delayed and careful introduction of enteral feeding. Such a policy exposes babies to the risks of parenteral nutrition, with no trials to date showing any benefit of delayed enteral nutrition. Trials are required to determine the optimum timing for introduction of enteral feeds in growth restricted infants with fetal AREDF.

Doppler waveforms: the relation between ductus venosus and inferior vena cava

This study was to assess whether or not there was correlation between the Doppler velocity waveform of the ductus venosus (DV) and inferior vena cava (IVC). A total of 142 healthy pregnant women were enrolled and divided into three groups according to the gestational weeks at the examination time. Group 1 was < or = 22 weeks; group 2 was between 22 and 28 weeks; and group 3 was > or = 28 weeks. Acuson 128xp was used to measure the Doppler velocity waveforms of DV and IVC by one experienced examiner. Doppler indices were used for analysis. Our results showed that, with the advance of pregnancy age, the resistance index of DV (DV-RI) and the preload index of IVC (IVC-PLI) were correlated with the gestational weeks, r = -0.247 and r = -0.540, respectively. There was a weak correlation between DV-RI and IVC-PLI, r = 0.202, p < 0.05; however, there was no significant correlation between DV-RI and IVC-PLI in group 1, group 2 or group 3. In conclusion, we report the first study on the correlation between DV-RI and IVC-PLI, which indicated the different roles of DV and IVC in fetal hemodynamics.

Antenatal predictors of neonatal outcome in fetal growth restriction with absent end-diastolic flow in the umbilical artery

OBJECTIVE

Absent end-diastolic blood flow in the umbilical artery identifies growth-restricted fetuses at high risk of perinatal mortality and severe morbidity. We explored antenatal variables predictive of perinatal mortality or severe neonatal morbidity in such fetuses.

STUDY DESIGN

We accessed a cohort of 39 singleton, non-malformed, growth-restricted fetuses with absent end-diastolic blood flow at less than 34 weeks between January 1995 and December 2004. The ratio of umbilical artery pulsatility index to middle cerebral artery pulsatility index was calculated to assess redistribution of the fetal arterial circulation. Prenatal and neonatal variables were compared between subjects with versus those without perinatal mortality or severe morbidity using unpaired Student t test or Fisher exact test. Statistical analysis included stepwise logistic regression and receiver operating characteristic curve analysis. P < .05 was considered significant.

RESULTS

Stepwise logistic regression analysis demonstrated that the last umbilical artery/middle cerebral artery ratio (P = .02) and estimated fetal weight before delivery (P = .02) were independent predictors of adverse neonatal outcome, with an umbilical artery/middle cerebral artery ratio 1.9 or greater having a sensitivity of 75% and a 13% false-positive rate. Umbilical artery/middle cerebral artery ratio alone accounted for 54% of the variability in outcome.

CONCLUSIONS

Among preterm growth-restricted fetuses with absent end-diastolic blood flow in the umbilical artery, the umbilical artery/middle cerebral artery ratio is the best predictor of neonatal mortality or severe morbidity.

Intrauterine growth restriction and absent or reverse end-diastolic blood flow in umbilical artery (Doppler class II or III): A retrospective study of short- and long-term fetal morbidity and mortality

OBJECTIVE

Absent or reverse end-diastolic flow (Doppler II/III) in umbilical artery is correlated with poor perinatal outcome, particularly in intrauterine growth restricted (IUGR) fetuses. The optimal timing of delivery is still controversial. We studied the short- and long-term morbidity and mortality among these children associated with our defined management.

STUDY DESIGN

Sixty-nine IUGR fetuses with umbilical Doppler II/III were divided into three groups; Group 1, severe early IUGR, no therapeutic intervention (n = 7); Group 2, fetuses with pathological biophysical profile, immediate delivery (n = 35); Group 3, fetuses for which expectant management had been decided (n = 27).

RESULTS

In Group 1, stillbirth was observed after a mean delay of 6.3 days. Group 2 delivered at an average of 31.6 weeks and two died in the neonatal period (6%). In Group 3 after a mean delay of 8 days, average gestational age at delivery was 31.7 weeks; two intra uterine and four perinatal deaths were observed (22%). Long-term follow-up revealed no sequelae in 25/31 (81%) and 15/18 (83%), and major handicap occurred in 1 (3%) and 2 patients (11%), respectively, for Groups 2 and 3.

CONCLUSION

Fetal mortality was observed in 22% of this high risk group. After a mean period of follow-up of 5 years, 82% of infants showed no sequelae. According to our management, IUGR associated with umbilical Doppler II or III does not show any benefit from an expectant management in term of long-term morbidity.

Diagnosis and management of intrauterine growth restriction

The growth-restricted fetus is a fetus who fails to reach his growth potential and is at risk for perinatal morbidity and mortality. When a fetus has an estimated weight below the 10th percentile, in the absence of congenital anomalies and in the presence of a normal amount of amniotic fluid, Doppler velocimetry gives the most important information to differentiate the truly growth-restricted fetus from the fetus that is constitutionally small but otherwise normal. One area of debate and research is whether Doppler velocimetry can help in timing the delivery of the growth-restricted fetus. Data appear to support the use of ductus venosus velocimetry in deciding when to deliver, but randomized data on this point are still lacking.

Importance of Ductus venosus Doppler Assessment for Fetal Outcome in Cases of Intrauterine Growth Restriction

OBJECTIVE

The measurement and evaluation of ductus venosus (DV) blood flow velocity waveform in high-risk pregnancies has been studied intensively in recent years in order to find a more intermediate signal of fetal compromise. Our objective was to study the fetal outcome of pregnancies with intrauterine growth retardation (IUGR) and normal pulsatility of DV compared to an IUGR group with increased DV pulsatility.

METHODS

The outcome of 42 fetuses before 32 weeks of gestational age without chromosomal or structural aberrations was analyzed. All fetuses showed IUGR <5th percentile based on placental insufficiency diagnosed by pathologic RI >90th percentile of both maternal uterine arteries. One group (30 fetuses; mean weight 730 g/SD 190 g; mean gestational age 197 days/SD 12 days) showed normal, the other (12 fetuses, mean weight 675 g/SD 179 g; mean gestational age 198 days/SD 12 days) reduced, but neither absent nor reverse DV flow during atrial contraction. All 42 fetuses were delivered by cesarean section because of severe variable or prolonged decelerations. We measured blood flow velocities of the DV in every fetus on an average 3.7 days (range 1-5 days) before cesarean section. Fetal outcome was determined by Apgar scores after 5 and 10 min, arterial pH and base excess; neonatal morbidity was recorded by intensive follow-up.

RESULTS

There were no significant differences of pH, umbilical artery base excess, Apgar scores and severe neonatal complications between the two groups.

CONCLUSIONS

Our own data show no correlation between increased pulsatility in the DV (without absent or reverse flow during atrial contraction) and fetal outcome before 32 gestational weeks, even in cases of severe growth restriction based on placental insufficiency. Therefore in these cases reduced DV flow during atrial contraction should cautiously be interpreted regarding obstetrical decisions.

Doppler application in the delivery timing of the preterm growth-restricted fetus: another step in the right direction

This article provides an opinion on a study of relationships between umbilical artery (UA) Doppler, ductus venosus (DV) Doppler, fetal heart rate variation, and perinatal outcome in preterm, intrauterine growth-restricted (IUGR) fetuses published in the same issue of this journal by Bilardo and coworkers. Recent evidence on venous Doppler surveillance in preterm IUGR fetuses was also reviewed and discussed in the context of the study with a special emphasis on delivery timing. A search was conducted through MEDLINE and eight articles with similar inclusion criteria and reporting format of outcomes were identified. Numbers for perinatal mortality, intraventricular hemorrhage, respiratory distress syndrome, bronchopulmonary dysplasia and necrotizing enterocolitis (NEC) were extracted for cases where Doppler status was recorded in an identical format. Proportional distribution of outcomes was compared for fetuses with normal DV Doppler velocimetry, absent or reversed UA end-diastolic velocity (UA A/REDV), elevated DV Doppler index (abnormal DV) and absence or reversal of atrial velocity in the DV (DV-RAV). A total of 320 fetuses with normal and 202 with elevated DV Doppler indices were extracted. Of these fetuses, 101 with UA A/REDV only and 34 with DV-RAV were identified. Perinatal mortality was 5.6% (16/282) with normal DV, 11.9% (12/101) with UA A/REDV, 38.8% (64/165) with abnormal DV and 41.2% (7/17) with DV-RAV. With the exception of NEC, all complications were significantly more frequent with abnormal DV. With normal venous Doppler neonatal deaths account for most of the perinatal mortality, while with abnormal DV stillbirths and neonatal mortality are similar contributors to the significantly increased perinatal mortality. In conclusion, UA Doppler is a placental function test that provides important diagnostic and prognostic information in preterm IUGR. DV Doppler effectively identifies those preterm IUGR fetuses that are at high risk for adverse outcome (particularly stillbirth) at least 1 week before delivery, independent of the UA waveform. Relationships between perinatal outcome, arterial and venous Doppler status and gestational age require ongoing observational research effort. Randomized management trials are necessary to verify that delivery timing based on venous Doppler will impact on outcome in preterm IUGR.

Cardiac function monitoring of fetuses with growth restriction

OBJECTIVE

To describe the time sequence of changes in cardiac function in intrauterine growth restriction.

STUDY DESIGN

This was a prospective longitudinal study on 22 singleton pregnancies with growth-restricted fetuses. Pulsatility indices of fetal arterial and venous Doppler waveforms, systolic peak velocity in the aorta and pulmonary artery, right and left ventricular shortening fraction and atrioventricular flow E/A ratio were assessed at each monitoring session. Logistic regression was used for modeling the probability of abnormality of a variable in relation to the time interval before delivery. Trends over time were analyzed by Mann-Withney U-test.

RESULTS

Umbilical artery pulsatility index was the first variable to become abnormal, followed by the middle cerebral artery, right diastolic indices (right E/A, ductus venosus), right systolic indices and, finally, both diastolic and systolic left cardiac indices.

CONCLUSION

We have found an earlier and more pronounced right than left and diastolic than systolic fetal cardiac function deterioration in growth restricted fetuses monitored longitudinally.

Doppler blood flow in obstetrics

PURPOSE OF REVIEW

Our review on Doppler ultrasound in obstetrics aims to identify which vessels have a definite clinical role in obstetrics.

RECENT FINDINGS

The use of Doppler ultrasonography in the diagnosis and management of the intrauterine growth-restricted fetus improves the perinatal morbidity and mortality. However, the timing of delivery of the intrauterine growth-restricted fetus, based on Doppler ultrasonography, remains the subject of investigation. Robust data exist on the management of fetuses at risk for anemia because of red cell alloimmunization by using the middle cerebral artery peak systolic velocity. Appropriate training for the correct assessment of this vessel is fundamental. Doppler ultrasonography of the umbilical artery is useful in the counseling of patients with pregnancies complicated by twin-twin transfusion syndrome.

SUMMARY

Recently, Doppler ultrasonography has been shown to be helpful to the obstetricians in the diagnosis of the IUGR fetus, diagnosis of fetal anemia, twin-twin transfusion syndrome. These are the basis for timing the delivery of the IUGR fetus. However, more data are necessary. Doppler ultrasonography should be used to assess the fetal ductus arteriosus in patients treated with prostaglandin inhibitors. Doppler is also an important part of the fetal echocardiogram.

Splenic artery Doppler in the prediction of the small-for-gestational age infant

OBJECTIVES

We hypothesized that, as with other areas of the peripheral circulation, fetal splenic artery blood flow undergoes changes in small-for-gestational age (SGA) fetuses due to a redistribution of cardiac output, and that the Doppler peak systolic velocity (PSV) reflects such changes and thus may be used to predict fetuses being SGA.

METHODS

Splenic artery Doppler PSV, end-diastolic velocity (EDV), resistance index (RI) and umbilical artery RI were measured prospectively in fetuses at risk for being SGA at birth. Normal reference data were generated from appropriately grown fetuses delivering at > or = 37 weeks without complications, and SGA was defined as birth weight < 10th percentile. The Doppler indices were expressed as multiples of the normal median (MoM) for gestational age. Using receiver operating characteristic curves, optimal Doppler thresholds for the detection of SGA cases were determined and the areas under the curves calculated. The analysis was limited to singleton pregnancies delivered within 2 weeks of the last Doppler examination.

RESULTS

There were 88 study patients of which 60 had SGA babies. The mean gestational age at Doppler examination was 31.4 weeks with a mean interval of 5.6 days from Doppler to delivery. The splenic artery PSV was lower in SGA, compared to normal cases: mean PSV (MoM), 0.93 vs. 1.09, respectively (P = 0.0001). The sensitivity, specificity and area under the curve were 70.0%, 72% and 0.734, respectively (P < 0.003), for the PSV in the prediction of delivery of a SGA fetus. For the splenic artery RI, values were 70%, 46% and 0.539, respectively (not significantly different), and for umbilical artery RI these were 70%, 61% and 0.689, respectively (P < 0.01). Splenic artery EDV was significantly reduced in SGA vs. normally grown fetuses (0.924 MoM vs. 1.145 MoM, P = 0.007).

CONCLUSIONS

Fetal splenic artery PSV decreases in SGA infants, and is a strong predictor of the delivery of a SGA infant. It appears to be superior to the standard Doppler index, the RI, in predicting this outcome.

[Criteria of pregnancy termination in women with preeclampsia]

Preeclampsia remains an important cause of maternal and neonatal mortality and morbidity. Delivery is always the appropriate therapy for the mother but may be responsible for neonatal adverse outcomes, particularly when it occurs at less than < 34 weeks' gestation. In women with severe preeclampsia at < 34 weeks expectant management to improve neonatal mortality and morbidity may be performed under close monitoring of both the mother and the fetus. Any severe condition of the mother (HELLP syndrome, abruptio placentae, eclampsia) or the fetus (abnormal fetal heart rate) should lead to prompt delivery. In women with mild preeclampsia, expectant management should be performed until 38 weeks gestation.

Abnormal fetal cerebral and umbilical Doppler measurements in fetuses with intrauterine growth restriction predicts the severity of perinatal morbidity

PURPOSE

This prospective study was performed to determine if the ratio of the middle cerebral artery (MCA) S/D ratio (ratio of peak systolic blood flow velocity to diastolic velocity) to the umbilical artery (UA) S/D ratio (MCA/UA S/D ratio) predicts the degree of neonatal morbidity in fetuses suspected of having intrauterine growth restriction (IUGR).

METHODS

Sixty-one fetuses were identified prospectively by sonography as having an estimated fetal weight below the 10th percentile for gestational age. The 61 fetuses underwent Doppler sonography in the third trimester and then were stratified into 3 groups based on the MCA/UA S/D ratio: group A, MCA/UA S/D ratio > 1.0 (controls; n = 37); group B, MCA/UA S/D ratio < or = 1.0 (intracerebral blood flow redistribution; n = 16); and group C, reversed or absent UA diastolic flow (n = 8). Outcome variables assessed included gestational age at delivery, birth weight, UA pH, mode of delivery, respiratory distress syndrome requiring intubation, and intracranial hemorrhage.

RESULTS

The mean MCA/UA S/D ratios in groups A and B were 1.69 + /- 0.61 and 0.59 + /- 0.24, respectively (p < 0.01). The mean gestational ages at delivery for groups A, B, and C were 34.7, 33.2, and 29.0 weeks, respectively. The mean birth weights were below the fifth percentile for age for groups B and C and significantly related to the severity of abnormal Doppler findings (p < 0.01) after correction for age. Mean UA pHs were 7.25 + /- 0.01, 7.19 + /- 0.01, and 7.14 + /- 0.13 for groups A, B, and C, respectively, with significant differences between groups A and B (p < 0.05) and groups A and C (p < 0.05). Respiratory distress syndrome and intracranial hemorrhage were not associated with abnormal Doppler findings after correction for gestational age. The interval between the abnormal Doppler examination and delivery (p < 0.001) and the occurrence of fetal distress requiring cesarean section (p < 0.001) were significantly related to the severity of Doppler findings.

CONCLUSIONS

In fetuses with suspected IUGR, abnormal MCA/UA S/D ratios are strongly associated with low gestational age at delivery, low birth weight, and low UA pH. Abnormal MCA/UA S/D ratios are also significantly associated with shorter interval to delivery and the need for emergent delivery.

Relationship between arterial and venous Doppler and perinatal outcome in fetal growth restriction

OBJECTIVE

The aim of this investigation was to assess the relationship between abnormal arterial and venous Doppler findings and perinatal outcome in fetuses with intrauterine growth restriction (IUGR).

METHODS

Doppler velocimetry of the umbilical artery (UA), middle cerebral artery (MCA), inferior vena cava (IVC), ductus venosus (DV) and free umbilical vein was performed in 121 IUGR fetuses with a UA pulsatility index (PI) > 2 SD above the gestational age mean and subsequent birth weight < 10th centile for gestational age. Groups based on the last Doppler exam were: 1 = abnormal UA-PI only (n = 42, 34.7%), 2 = MCA-PI > 2 SD below the gestational age mean (= 'brain sparing') in addition to abnormal UA-PI (n = 29, 24.0%), 3 = DV or IVC peak velocity index (PVIV) > 2 SD above the gestational age mean and/or pulsatile UV flow (n = 50, 41.3%). Z-scores (delta indices) were calculated for Doppler indices. Perinatal mortality, respiratory distress (RDS), bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), necrotizing enterocolitis (NEC), circulatory failure and umbilical artery blood gases were recorded.

RESULTS

Absence or reversal of umbilical artery end-diastolic flow was observed in 4 (9.5%) of fetuses in group 1, 10 (34.5%) fetuses in group 2 and 41 (82%) fetuses in group 3. A low middle cerebral artery pulsatility index was found in 39 (78%) fetuses in group 3. Multiple regression analysis with gestational age at delivery, delta indices and cord artery blood gas as independent parameters and individual perinatal outcomes as dependent variables was performed. In this analysis the association was strongest with gestational age for each complication. There were no significant differences in Apgar scores between groups. At delivery, 'brain sparing' was associated with hypoxemia and abnormal venous flows with acidemia. Perinatal mortality was highest in group 3 and stillbirth was only observed when venous flow was abnormal. All postpartum complications were more frequent in fetuses with abnormal venous flows. The only statistically significant relation between Doppler indices and outcome was the association between abnormal ductus venosus flow and fetal death (r2 = 0.24, P < 0.05).

CONCLUSION

Growth restricted fetuses with abnormal venous flow have worse perinatal outcome compared to those where flow abnormality is confined to the umbilical or middle cerebral artery. In fetuses with low middle cerebral artery pulsatility, venous Doppler allows detection of further deterioration. While abnormal venous flows can be significantly associated with fetal demise, gestational age at delivery significantly impacts on all short-term outcomes.

Vascular Doppler techniques

Doppler ultrasound used for the assessment of the fetal umbilical circulation in the human pregnancy has been reported in the scientific literature since the early 1980s and has been rigorously evaluated by randomized, controlled trials. The consensus of the reviewers of these trials is that there do appear to be grounds for including umbilical artery Doppler ultrasound studies in the management of high-risk pregnancies. There is no apparent benefit for low-risk pregnancies or later gestation. Other fetal vascular beds are currently undergoing prospective studies and some limited randomized, controlled trials have been reported; but to date they are not at a point of development to be considered part of clinical management.

Prediction of perinatal outcome in fetuses suspected to have intrauterine growth restriction: Doppler US study of fetal cerebral, renal, and umbilical arteries

PURPOSE

To determine and compare the diagnostic performance of fetal middle cerebral (MCA), renal (RA), and umbilical (UA) arterial Doppler ultrasonography (US) for prediction of adverse perinatal outcome in suspected intrauterine growth restriction (IUGR).

MATERIALS AND METHODS

Two hundred ninety-three small-for-gestational age fetuses (24-39 weeks at recruitment and US-estimated weight or abdominal circumference below 10th percentile) were prospectively examined with Doppler US of the UA, MCA, and RA. Clinicians were blinded to MCA and RA Doppler measurements.

RESULTS

Seventy-six fetuses (25.9%) had at least one major or minor adverse perinatal outcome. Major outcomes included stillbirth, neonatal death, neurologic complication, and necrotizing enterocolitis. The MCA pulsatility index (PI), compared with the UA PI and RA PI, was more sensitive (72.4% vs 44.7% and 8.3%) but less specific (58.1% vs 86.6% and 92.6%) in predicting adverse outcome. The UA PI had the highest positive likelihood ratio (ratio, 3.3); the MCA PI had the lowest negative likelihood ratio (ratio, 0.48). When gestational age at the first Doppler US examination was less than 32 weeks, the MCA PI had a sensitivity of 95.5% and negative predictive value of 97.7% for major adverse outcome (negative likelihood ratio, 0.10).

CONCLUSION

In suspected IUGR, while an abnormal UA PI is a better predictor of adverse perinatal outcome than an abnormal MCA or RA PI, a normal MCA PI may help to identify fetuses without major adverse perinatal outcome, especially before 32 weeks gestational age.

Assessment of fetal cardiovascular function: ultrasound study of the fetal circulatory compartments

Recent advances in high-resolution ultrasonography combined with color-coded Doppler analysis have enabled a new insight to be gained into fetal physiology and allowed the investigation of small, previously inaccessible fetal vessels under normal and abnormal conditions. In addition, the findings in some cases contradict the accepted fetal pathophysiology derived from animal studies. The aim of the present study is to describe new reports assessing the major compartments of the fetal cardiovascular system (heart, lung, splanchnic and fetal venous circulations) and to discuss the developments in these fields.