Umbilical Artery Doppler Indices Research Articles

Cord blood oxidative stress markers correlate with umbilical artery pulsatility in fetal growth restriction

Objective: To compare cord blood oxidative stress markers (OSM) between intrauterine small fetuses with high umbilical artery (UA) Doppler indices and normal indices. Methods: Forty women who had oligohydramnios and intrauterine growth-restricted fetuses with abnormal (n = 20, group I) or normal Doppler indices (n = 20, group II) were included. All patients underwent fetal Doppler ultrasound studies. Cord blood was collected at birth and six OSMs (ischemia-modified albumin (IMA), hepatocyte growth factor (HGF), malondialdehyde (MDA)) levels, total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI) were studied. Results: The mean cord blood IMA, MDA, TOS, and OSI values for group I were significantly increased when compared to the group II (p < 0.001 for IMA, MDA, TOS, and OSI). However the mean cord blood HGF and TAS values were statistically significantly decreased in group I, compared with group II (p < 0.001 for HGF, and TAS). A significant positive (for IMA, MDA,TOS levels, and OSI ratio) and negative (for HGF and TAS levels) correlations between UA pulsatility index (PI) and cord blood OSM were found. Conclusion: The correlation between cord blood OSM and Doppler blood flow changes shown in this study may contribute to understanding the underlying oxidative stress-related mechanisms.

Spatiotemporal image correlation‐derived volumetric Doppler impedance indices from spherical samples of the placenta: intraobserver reliability and correlation with conventional umbilical artery Doppler indices

Volumetric impedance indices derived from spatiotemporal image correlation (STIC) power Doppler ultrasound (PDU) might overcome the influence of machine settings and attenuation. We examined the feasibility of obtaining these indices from spherical samples of anterior placentas in healthy pregnancies, and assessed intraobserver reliability and correlation with conventional umbilical artery (UA) impedance indices. Uncomplicated singleton pregnancies with anterior placenta were included in the study. A single observer evaluated UA pulsatility index (PI), resistance index (RI) and systolic/diastolic ratio (S/D) and acquired three STIC-PDU datasets from the placenta just above the placental cord insertion. Another observer analyzed the STIC-PDU datasets using Virtual Organ Computer-aided AnaLysis (VOCAL) spherical samples from every frame to determine the vascularization index (VI) and vascularization flow index (VFI); maximum, minimum and average values were used to determine the three volumetric impedance indices (vPI, vRI, vS/D). Intraobserver reliability was examined by intraclass correlation coefficients (ICC) and association between volumetric indices from placenta, and UA Doppler indices were assessed by Pearson's correlation coefficient. A total of 25 pregnant women were evaluated but five were excluded because of artifacts observed during analysis. The reliability of measurement of volumetric indices of both VI and VFI from three STIC-PDU datasets was similar, with all ICCs ≥ 0.78. Pearson's r values showed a weak and non-significant correlation between UA pulsed-wave Doppler indices and their respective volumetric indices from spherical samples of placenta (all r ≥ 0.23). VOCAL indices from specific phases of the cardiac cycle showed good repeatability (ICC ≥ 0.92). Volumetric impedance indices determined from spherical samples of placenta are sufficiently reliable but do not correlate with UA Doppler indices in healthy pregnancies.

P30.09: Correlation between STIC Power Doppler impedance indices from spherical samples of the placenta and conventional umbilical artery Doppler indices in normal pregnancies

Objectives: The objective of the study was to evaluate differences in post partum bleeding, transfusion requirement and length of hospital stay in women with focal vs. diffuse placenta accreta. The same parameters were compared in women undergoing balloon occlusion vs. no occlusion of the iliac arteries at Caesarean delivery for accreta. Methods: Prospective observational study of women with suspected focal or diffuse placenta accreta on routine sonography. Follow up scans were performed as required. Surgical and histologic correlation was performed after Caesarean delivery. Independent groups t-tests and non-parametric Mann-Whitney U were used in the statistical analysis. Results: 25 women were diagnosed on ultrasound with placenta accreta, 9 with focal accreta and 16 with diffuse involvement. On average, women in the diffuse group exhibited significantly greater blood loss (P < 0.001) than the focal group and had a higher transfusion requirement (P = 0.12). There was no significant difference in hospital stay between the groups. 12 women underwent balloon iliac occlusion at Caesarean delivery, 2 of whom had focal accreta diagnosed prenatally and 10 had diffuse accreta. There were no significant differences in blood loss, transfusion requirement or length of hospital stay between the balloon vs. no-balloon occlusion groups. Conclusions: Prenatal diagnosis of extent of placenta accreta is clinically important and should guide management around delivery. Although the numbers in this study are small, no significant differences in blood loss or transfusion requirement were observable between the balloon occlusion vs. no occlusion group. Further studies are required to assess whether this is a worthwhile and cost-effective intervention in management of placenta accreta.

OP11.01: Interobserver variability in the ultrasound diagnosis of congenital uterine anomalies

Methods: A web-based survey of fellows and trainees of the Royal Australian and New Zealand College of Obstetricians and Gynaecologists. Results: Three hundred and sixty-six (28%) responses included about 50% of Fetal Medicine and Obstetric Ultrasound subspecialists. Just over /4 (76.1%) of practices report or receive reports as a systolic:diastolic ratio (SD), just under 1/3 (31.6%) as pulsatility index (PI) and over 1/3 (36.4%) as resistance index (RI) with 22% declining to nominate a preferred umbilical artery Doppler index. 57% did not know the reference source used in their practice and more than 30% cited unpublished, local reference ranges. Many respondents were well aware of the limitations of umbilical artery Doppler. Survey participants requested 1. consistency 2. gestational age specific reference ranges 3. guidance in interpretation. Conclusions: Regarding Doppler indices, SD remains popular. RI advocates note its straightforward interpretation. PI is favoured by subspecialists, those following international research and those using ratios (e.g. cerebro-placental ratio). Until one index becomes universal, co-reporting of all indices is prudent. Concerning reference chart choice, local, unpublished charts remain popular: their concordance requires investigation. Generally, ideal reference chart are 1. Drawn from a representative population 2. not drawn from a referred population (biased toward abnormality) 3. not subject to retrospective exclusions (biased to ‘‘super-normality’’) 4. Developed using valid statistics, especially to estimate extreme values 5. Use optimal information about gestation 6. Use a good sample size. Ideally usable charts should be subject to peer review and publication, ASUM and RANZCOG endorsement, be readily accessible on ultrasound machines, reporting packages, smart phone applications and the world wide web

OP11.03: How early can conception be accurately diagnosed following embryo transfer in IVF treatment?

Methods: A web-based survey of fellows and trainees of the Royal Australian and New Zealand College of Obstetricians and Gynaecologists. Results: Three hundred and sixty-six (28%) responses included about 50% of Fetal Medicine and Obstetric Ultrasound subspecialists. Just over /4 (76.1%) of practices report or receive reports as a systolic:diastolic ratio (SD), just under 1/3 (31.6%) as pulsatility index (PI) and over 1/3 (36.4%) as resistance index (RI) with 22% declining to nominate a preferred umbilical artery Doppler index. 57% did not know the reference source used in their practice and more than 30% cited unpublished, local reference ranges. Many respondents were well aware of the limitations of umbilical artery Doppler. Survey participants requested 1. consistency 2. gestational age specific reference ranges 3. guidance in interpretation. Conclusions: Regarding Doppler indices, SD remains popular. RI advocates note its straightforward interpretation. PI is favoured by subspecialists, those following international research and those using ratios (e.g. cerebro-placental ratio). Until one index becomes universal, co-reporting of all indices is prudent. Concerning reference chart choice, local, unpublished charts remain popular: their concordance requires investigation. Generally, ideal reference chart are 1. Drawn from a representative population 2. not drawn from a referred population (biased toward abnormality) 3. not subject to retrospective exclusions (biased to ‘‘super-normality’’) 4. Developed using valid statistics, especially to estimate extreme values 5. Use optimal information about gestation 6. Use a good sample size. Ideally usable charts should be subject to peer review and publication, ASUM and RANZCOG endorsement, be readily accessible on ultrasound machines, reporting packages, smart phone applications and the world wide web

Role of Colour Doppler Indices in the Diagnosis of Intrauterine Growth Retardation in High-Risk Pregnancies

Intra uterine growth retardation (IUGR) due to fetoplacental vascular insufficiency is rampant in developing countries like India. Owing to the lack of awareness, antenatal patients often present in their third trimester for their first ultrasound examination. Alterations in the waveforms and Doppler indices of fetal middle cerebral artery (MCA), umbilical artery and bilateral uterine arteries have been extensively described in various studies in the literature. However, the role of each doppler parameter in actually predicting reduced birth weight (for gestational age) in the third trimester is often debatable and frustrating. A prospective study was done on 100 patients of clinically suspected IUGR/high-risk pregnancies of 31-41weeks. The cases were followed till delivery; the doppler and grey scale findings were correlated with the birth weight of the baby. The highest sensitivity was found to be of HC/AC ratio, (84.4%), the highest specificity of oligohydramnios and Cerebral/Umbilical Pulsatility ratio[C/U ratio] (100%). The sensitivity of C/U ratio was found to be 68.8%. Fetal MCA had the lowest sensitivity (7.7%). HC/AC ratio is quite sensitive, and oligohydramnios is a highly specific parameter to diagnose IUGR. However, the former has lower specificity, and the latter has very poor sensitivity. The MCA PI alone is not sensitive at all, and should not be used for screening purposes in IUGR patients. Also, C/U ratio is more sensitive than oligohydramnios and more specific than HC/AC ratio and stands out as the best parameter of all to diagnose IUGR in the third trimester.

Strenuous exercise during pregnancy: is there a limit?

The purpose of this study was to evaluate fetal responses to strenuous exercise in physically active and inactive women. Forty-five healthy women (15 who were nonexercisers, 15 who were regularly active, 15 who were highly active) underwent a peak treadmill test at 28 weeks' gestation to 32 weeks 6 days' gestation. Fetal well-being (umbilical artery Doppler indices, fetal heart tracing/rate, biophysical profile [BPP]) was evaluated before and after exercise. Uterine artery Doppler scans were also obtained. Umbilical and uterine artery Doppler indices were similar among activity groups and did not change with exercise (P > .05). BPP and fetal heart tracings were reassuring in all groups. However, subgroup analyses showed transient fetal heart rate decelerations after exercise and elevated umbilical and uterine artery Doppler indices in 5 highly active women. After this, BPP and fetal heart tracings were reassuring. Overall fetal well-being is reassuring after short-duration, strenuous exercise in both active and inactive pregnant women. A subset of highly active women experienced transient fetal heart rate decelerations and Doppler changes immediately after exercise. Athletes may push beyond a threshold intensity at which fetal well-being may be compromised. However, potential impact on neonatal outcomes is unknown.

Fetoplacental biometry and umbilical artery Doppler velocimetry in the overnourished adolescent model of fetal growth restriction

The purpose of this study was to evaluate ultrasonographically fetal growth trajectories, placental biometry, and umbilical artery (UA) Doppler indices in growth-restricted pregnancies of overnourished adolescent ewes and normally developing pregnancies of control-fed ewes. Singleton pregnancies were established using embryo transfer in 42 adolescent ewes that were overnourished (n = 27) or control-fed (n = 15) and were scanned at weekly intervals from 83-126 days' gestation and necropsied at 131 days' gestation (term = 145 days). Ultrasonographic placental measurements were reduced and UA Doppler indices were increased from 83 days' gestation; measurements of fetal abdominal circumference and femur length, renal volume and tibia length, and biparietal diameter were reduced from 98, 105, and 112 days' gestation, respectively, in overnourished vs control-intake pregnancies. Overnourishment of adolescent sheep dams produced late-onset asymmetric fetal growth restriction that was commensurate with brain sparing. Ultrasonographic placental biometry was already reduced and UA Doppler indices increased by mid gestation in overnourished pregnancies, preceding reduced fetal growth velocity and indicating an early nutritionally mediated insult on placental development.

Performance of third‐trimester ultrasound for prediction of small‐for‐gestational‐age neonates and evaluation of contingency screening policies

To assess the performance of third-trimester fetal biometry and fetal Doppler studies for the prediction of small-for-gestational-age (SGA) neonates, and to explore contingency strategies using a first-trimester prediction model based on maternal and fetal parameters and third-trimester ultrasound. This was an observational cross-sectional study of uncomplicated singleton pregnancies. Risk assessment for chromosomal abnormality was carried out in 4702 pregnancies using a combination of ultrasound markers (fetal nuchal translucency thickness (NT) and nasal bone assessment) and biochemistry (free beta-human chorionic gonadotropin (β-hCG) and pregnancy-associated plasma protein-A (PAPP-A)) at 11 to 13 + 6 weeks. Maternal demographic characteristics and method of conception were recorded. Third-trimester (30-34 weeks) fetal biometry (biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC) and femur length (FL)) and umbilical artery (UA) and middle cerebral artery Doppler studies were performed routinely in a subgroup (n = 2310). Reference ranges for birth weight were constructed using the cohort of 4702 women, and neonates were classified as small (SGA, ≤ 5th centile) or appropriate (AGA) for gestational age. First-trimester, third-trimester and integrated first- and third-trimester prediction models for SGA were constructed using regression analysis and three different contingency strategies of rescanning in the third trimester were investigated. According to the areas under the receiver-operating characteristics curves (AUCs), AC (AUC = 0.85) and ultrasound-estimated fetal weight (EFW, AUC = 0.87) were equally good predictors of SGA. The model was marginally improved by the addition of UA Doppler, smoking status and first-trimester indices (free β-hCG and PAPP-A multiples of the median) (combined model, AUC = 0.88), but the difference was not statistically significant. A contingency strategy of rescanning 50% of the population in the third trimester according to the risk estimated by a first-trimester prediction model yielded a detection rate of 79% for a 25% screen-positive rate. Third-trimester ultrasound is effective in screening for SGA in uncomplicated pregnancies. The use of a contingency screening policy can reduce the need for unnecessary examinations.

OC12.05: Umbilical artery Doppler indices and ultrasonographic placental biometry in relation to pregnancy outcome in a paradigm of fetal growth restriction

Objectives: Nutritional manipulation of pregnant adolescent sheep results in compromised fetoplacental growth and premature delivery of low birthweight lambs. Herein umbilical arterial (UA) Doppler indices and ultrasonographic placental biometry were investigated in relation to pregnancy outcome at term. Methods: Singleton pregnancies to a single sire were established in 14 adolescent ewes and subsequently nutritionally manipulated to generate a wide range of fetal sizes. Fetal biometry, UA Doppler indices and placental index (sum of cross-sectional areas of 10 representative placentomes) were measured by weekly ultrasound between 78.8 and 132.5d gestation. Lamb birthweight and fetal placental (cotyledon) weight were determined following spontaneous delivery near term (145d). Results: One stillborn and 13 live lambs (weighing 1496g–6050g, mean 3485g) were delivered at 132–145d (mean 140d). Birthweight was strongly correlated with placental weight (r=0.901, p=0.001) and was unrelated to baseline fetal biometry at 78.8d. In contrast, placental index at 78.8d was positively correlated with eventual birthweight (r=0.642, p=0.013) and placental weight per se (r=0.637, p=0.026) at term. Placental index correlated with birthweight throughout late gestation (r=0.660–0.712, p=0.004–0.011) but not with placental weight after 108.4d. UA pulsatility index (PI) correlated negatively with birthweight from 95.0d (r=-0.812, p=0.014) and placental weight from 101.3d (r=-0.820, p=0.001) onwards (r=-0.606–0.847, p=<0.001–0.022). Correlations for UA resistance index (r=-0.737–0.868) and systolic:diastolic ratio (r=-0.584–0.842) were similar to PI. Conclusions: Birthweight correlates positively with ultrasonographic assessment of placental size in mid-gestation, prior to slowing of the fetal growth trajectory, and negatively with UA Doppler indices throughout the final third of gestation. Higher Doppler indices and smaller placental size are associated with a greater degree of fetal growth restriction in this experimental paradigm.

Estrogen Receptor-β and Fetoplacental Endothelial Prostanoid Biosynthesis: A Link to Clinically Demonstrated Fetal Growth Restriction

Fetal growth restriction (FGR) due to placental dysfunction impacts short- and long-term neonatal outcomes. Abnormal umbilical artery Doppler velocimetry indicating elevated fetoplacental vascular resistance has been associated with fetal morbidity and mortality. Estrogen receptors are regulators of vasomotor tone, and fetoplacental endothelium expresses estrogen receptor-β (ESR2) as its sole estrogen receptor. Our objective was to elucidate the mechanism whereby ESR2 regulates placental villous endothelial cell prostanoid biosynthesis. We conducted immunohistochemical analysis of human placental specimens and studies of primary fetoplacental endothelial cells isolated from subjects with uncomplicated pregnancies. We evaluated in vivo levels of ESR2 and cyclooxygenase-2 (PTGS2) in villous endothelial cells from fetuses with or without FGR and/or abnormal umbilical artery Doppler indices and in vitro effects of ESR2 on prostanoid biosynthetic gene expression. ESR2 and PTGS2 expression were significantly higher within subjects with FGR with abnormal umbilical artery Doppler indices in comparison with controls (P < 0.01). ESR2 knockdown led to decreased cyclooxygenase-1 (PTGS1), PTGS2, prostaglandin F synthase (AKR1C3), and increased prostacyclin synthase (PTGIS), with opposing results found after ESR2 overexpression (P < 0.05). ESR2 mediates prostaglandin H2 substrate availability and, in the setting of differential regulation of AKR1C3 and PTGIS, altered the balance between vasodilatory and vasoconstricting prostanoid production. Higher ESR2 expression in the placental vasculature of FGR subjects with abnormal blood flow is associated with an endothelial cell phenotype that preferentially produces vasoconstrictive prostanoids. Endothelial ESR2 appears to be a master regulator of prostanoid biosynthesis and contributes to high-resistance fetoplacental blood flow, thereby increasing morbidity and mortality associated with FGR.

Umbilical Artery Doppler Velocimetry in a Sheep Model of Fetal Growth Restriction

PurposeOvernourishing adolescent sheep dams results in placental and fetal growth restriction. We aimed to evaluate changes in the umbilical arterial (UA) Doppler waveform in relation to altered fetal growth velocity in these compromised pregnancies.Material & MethodsSingleton pregnancies of known gestational age were established in 36 adolescent ewe-lambs using embryo transfer. Dams were offered a control diet (n = 12) or overnourished (n = 24), resulting in normal and compromised fetal growth trajectories, respectively. Ultrasonographic fetal biometry and UA Doppler indices were measured weekly between mid-gestation and necropsy at 131.0 ± 0.30 days (term = 145days).ResultsAt 83.1±0.16days there were no significant differences in fetal biometry, but UA resistance index and systolic:diastolic ratio were already higher in overnourished ewes (p = 0.022). Differences in UA pulsatility index reached significance at 98.0 ± 0.07days (p ≤ 0.001). Values of all three Doppler indices progressively fell throughout gestation but remained different between groups (p = 0.001–0.032). Relative to controls, fetal abdominal circumference, renal volume and femur/tibia lengths were decreased from 104.6±0.13days (p = 0.001–0.023) in overnourished ewes whilst biparietal diameter was not reduced until 111.8±0.09days (p = 0.015), indicating an asymmetric pattern of growth. At necropsy fetal weight was lower in overnourished versus control groups (4110±168g vs. 5133±136g, p = 0.001). Relative brain weight was increased (11.1g/kg vs.9.1g/kg, p = 0.001) commensurate with fetal brain sparing.ConclusionChanges in UA Doppler indices precede slowing of the fetal growth trajectory in overnourished adolescent sheep dams. This may reflect altered vascularity in the downstream fetal placental compartment. PurposeOvernourishing adolescent sheep dams results in placental and fetal growth restriction. We aimed to evaluate changes in the umbilical arterial (UA) Doppler waveform in relation to altered fetal growth velocity in these compromised pregnancies. Overnourishing adolescent sheep dams results in placental and fetal growth restriction. We aimed to evaluate changes in the umbilical arterial (UA) Doppler waveform in relation to altered fetal growth velocity in these compromised pregnancies. Material & MethodsSingleton pregnancies of known gestational age were established in 36 adolescent ewe-lambs using embryo transfer. Dams were offered a control diet (n = 12) or overnourished (n = 24), resulting in normal and compromised fetal growth trajectories, respectively. Ultrasonographic fetal biometry and UA Doppler indices were measured weekly between mid-gestation and necropsy at 131.0 ± 0.30 days (term = 145days). Singleton pregnancies of known gestational age were established in 36 adolescent ewe-lambs using embryo transfer. Dams were offered a control diet (n = 12) or overnourished (n = 24), resulting in normal and compromised fetal growth trajectories, respectively. Ultrasonographic fetal biometry and UA Doppler indices were measured weekly between mid-gestation and necropsy at 131.0 ± 0.30 days (term = 145days). ResultsAt 83.1±0.16days there were no significant differences in fetal biometry, but UA resistance index and systolic:diastolic ratio were already higher in overnourished ewes (p = 0.022). Differences in UA pulsatility index reached significance at 98.0 ± 0.07days (p ≤ 0.001). Values of all three Doppler indices progressively fell throughout gestation but remained different between groups (p = 0.001–0.032). Relative to controls, fetal abdominal circumference, renal volume and femur/tibia lengths were decreased from 104.6±0.13days (p = 0.001–0.023) in overnourished ewes whilst biparietal diameter was not reduced until 111.8±0.09days (p = 0.015), indicating an asymmetric pattern of growth. At necropsy fetal weight was lower in overnourished versus control groups (4110±168g vs. 5133±136g, p = 0.001). Relative brain weight was increased (11.1g/kg vs.9.1g/kg, p = 0.001) commensurate with fetal brain sparing. At 83.1±0.16days there were no significant differences in fetal biometry, but UA resistance index and systolic:diastolic ratio were already higher in overnourished ewes (p = 0.022). Differences in UA pulsatility index reached significance at 98.0 ± 0.07days (p ≤ 0.001). Values of all three Doppler indices progressively fell throughout gestation but remained different between groups (p = 0.001–0.032). Relative to controls, fetal abdominal circumference, renal volume and femur/tibia lengths were decreased from 104.6±0.13days (p = 0.001–0.023) in overnourished ewes whilst biparietal diameter was not reduced until 111.8±0.09days (p = 0.015), indicating an asymmetric pattern of growth. At necropsy fetal weight was lower in overnourished versus control groups (4110±168g vs. 5133±136g, p = 0.001). Relative brain weight was increased (11.1g/kg vs.9.1g/kg, p = 0.001) commensurate with fetal brain sparing. ConclusionChanges in UA Doppler indices precede slowing of the fetal growth trajectory in overnourished adolescent sheep dams. This may reflect altered vascularity in the downstream fetal placental compartment. Changes in UA Doppler indices precede slowing of the fetal growth trajectory in overnourished adolescent sheep dams. This may reflect altered vascularity in the downstream fetal placental compartment.

Reference values for Doppler indices of the umbilical and fetal middle cerebral arteries in uncomplicated third trimester pregnancy

Introduction: The purpose of this study was to categorize new reference ranges for measurements of commonly used umbilical artery and fetal middle cerebral artery Doppler indices (Pulsatility Index, Resistance Index, and Systolic: Diastolic ratio) in uncomplicated third trimester pregnancy. Methods: This was a prospective cross sectional study involving 101 singleton uncomplicated pregnancies of 30 to 37 weeks of gestation. Umbilical artery indices were obtained from free floating loop and middle cerebral Doppler indices were obtained from the proximal third of the artery with flow towards the probe. Regression equations were used to categorize reference ranges and percentile fitted Normograms were obtained for all the parameters. Results: Among 101 singleton pregnancies between 30 and 37 weeks of gestation, 65 (64.35%) were primigravida women and 36 (34.65%) were multigravida. Mean maternal age was 23.12years (range 16 to 35 years). Maximum number of pregnancies (18.81%) was at 34 weeks of gestation. The established percentiles of Doppler indices showed a continuous reduction of all the measured indices as pregnancy increases (p&lt;0.0001). Conclusions: Reference ranges were obtained for the middle cerebral artery and umbilical artery Doppler indices. These ranges are consistent with similar studies done by other authors. Keywords: Doppler study; fetal Middle cerebral artery; pulsatility index; resistance index; systolic; diastolic ratio; umbilical artery DOI: http://dx.doi.org/10.3126/joim.v32i3.4953 Journal of Institute of Medicine, December, 2010; 32:3 5-13

Reference values for Doppler indices of the umbilical and fetal middle cerebral arteries in uncomplicated third trimester pregnancy

Introduction: The purpose of this study was to categorize new reference ranges for measurements of commonly used umbilical artery and fetal middle cerebral artery Doppler indices (Pulsatility Index, Resistance Index, and Systolic: Diastolic ratio) in uncomplicated third trimester pregnancy. Methods: This was a prospective cross sectional study involving 101 singleton uncomplicated pregnancies of 30 to 37 weeks of gestation. Umbilical artery indices were obtained from free floating loop and middle cerebral Doppler indices were obtained from the proximal third of the artery with flow towards the probe. Regression equations were used to categorize reference ranges and percentile fitted Normograms were obtained for all the parameters. Results: Among 101 singleton pregnancies between 30 and 37 weeks of gestation, 65 (64.35%) were primigravida women and 36 (34.65%) were multigravida. Mean maternal age was 23.12years (range 16 to 35 years). Maximum number of pregnancies (18.81%) was at 34 weeks of gestation. The established percentiles of Doppler indices showed a continuous reduction of all the measured indices as pregnancy increases (p&lt;0.0001). Conclusions: Reference ranges were obtained for the middle cerebral artery and umbilical artery Doppler indices. These ranges are consistent with similar studies done by other authors.

The impact of umbilical and uterine artery Doppler indices on antenatal course, labor and delivery in a low-risk primigravid population

To evaluate the impact of umbilical and uterine artery Doppler in the second and third trimester on antenatal course, labor and delivery in a low-risk primigravid population. Prospective recruitment of 1011 low-risk primigravidas with uterine and umbilical artery Doppler assessment at 22-24 weeks and 36 weeks. All mothers and infants were reviewed postnatally with a retrospective analysis of ultrasound and clinical outcome data. Elevated uterine artery indices were associated with increased rates of threatened miscarriage, higher rates of pre-eclampsia (PET) and a higher incidence of fetal birth weight <2nd and 9th centile for gestation. Uterine artery pulsatility index (PI) >95th centile for gestation was associated with statistically higher rates of small-for-gestational age (SGA) infants. Elevated umbilical artery indices were associated with higher rates of induction of labor and a higher incidence of fetal birth weight infants <2nd and 9th centile for gestation. Umbilical artery PI >95th centile for gestation was associated with statistically higher rates of SGA infants. Elevated uterine and umbilical artery indices are associated with higher rates of maternal and fetal disease.

Comparison of Modified Biophysical Profile and Doppler Ultrasound in Predicting the Perinatal Outcome at or over 36 Weeks of Gestation

Aims: In this study, modified biophysical profile (MBP) and uterine and umbilical artery Doppler ultrasonographic (USG) analysis were compared in predicting the perinatal outcome of pregnancies at ≧36 weeks. Methods: Three hundred and fifteen pregnant women were included in this study. Following routine examination, amniotic fluid index, uterine and umbilical artery Doppler indices were evaluated. Nonstress test (NST) was done and MBP was generated. Non-reassuring fetal status (NRFS), perinatal mortality, 5-min APGAR score and umbilical artery pH results were used in evaluating the perinatal outcome. Results: In groups with abnormal MBP and Doppler analysis the results of all parameters were bad. The statistical difference between the groups of normal and abnormal MBP and Doppler analysis was significant. In predicting the NRFS, MBP sensitivity was 60%, umbilical artery Doppler was 50% and uterine artery Doppler was 30%. In case of combination of findings of MBP and umbilical artery Doppler, the sensitivity rose to 70%. Conclusion: MBP was proved to be more significant than Doppler analysis in prediction of NRFS and perinatal results, but the sensitivity was increased when both were combined, so combination of MBP and Doppler analysis instead of MBP alone is more significant in antenatal assessment.

Umbilical Artery Doppler Indices in Small for Gestational Age Fetuses

The purpose of this study was to compare the screening efficiency of the umbilical artery systolic to diastolic ratio (S/D), pulsatility index (PI), and absent end-diastolic flow (AEDF) for adverse pregnancy outcomes and placental abnormalities in small for gestational age (SGA) fetuses. We conducted a retrospective cohort study of Doppler examinations of 161 nonanomalous SGA fetuses. The reliability of the S/D and PI were quantified by intraclass correlation coefficients. The association of the S/D, PI, and AEDF with adverse outcomes and placental abnormalities was compared by the chi(2) test. There was a simple association of Doppler results with adverse outcomes, which was mitigated when controlled for gestational age. For all measures of adverse outcomes, the specificity of abnormal Doppler results exceeded the sensitivity, and the negative predictive value was greater than the positive predictive value. Comparing the S/D with the PI, there was no significant difference in the sensitivity; however, the specificity of the PI was at least 90% and exceeded that of the S/D for all outcomes. The intraclass correlation coefficients of the S/D and PI were similar, indicating no difference in reliability. Placental abnormalities were significantly more common in cases with abnormal Doppler values (positive predictive value, 94%) with no overlap in the types of placental lesions in most cases. As an initial screen for adverse outcomes in SGA fetuses, the umbilical artery Doppler S/D, PI, and AEDF were imprecise. However, these measures were all strongly and similarly predictive of placental abnormalities, especially lesions of maternal underperfusion and fetal vascular obstruction.

Effect of short-term maternal fasting in the third trimester on uterine, umbilical, and fetal middle cerebral artery Doppler indices

Objective To assess the effect of short-term maternal fasting on uterine, umbilical, and middle cerebral artery Doppler indices, and on maternal serum glucose levels and fetal behavior. Methods Maternal serum glucose levels, fetal biophysical profiles, and uterine, umbilical, and middle cerebral artery Doppler indices were assessed in 110 healthy women in the third trimester of pregnancy after fasting for 10–12 hours and 2 hours after a balanced meal. Results Maternal serum glucose levels, nonstress test results, fetal breathing movements, and biophysical profile improved after a meal compared with after fasting for 10–12 hours. Uterine, umbilical, and middle cerebral artery Doppler indices were not significantly different after fasting and after a meal. Conclusion Short-term maternal fasting during the third trimester of pregnancy has no effect on uterine, umbilical, or fetal cerebral artery Doppler indices, and has a transient but significant effect on maternal serum glucose levels and fetal behavior.

Reply

We appreciate Dr Carvalho's interest in our study, which reported normal values for the ‘half peak systolic velocity deceleration time’ in the umbilical artery from 532 normal second- and third-trimester fetuses1. We further used this technique to evaluate placental resistance in seven fetuses with bradycardia, as this Doppler index is independent of the fetal heart rate (FHR). This is not the case for other umbilical artery Doppler indices currently in use, such as the systolic-to-diastolic ratio, resistance index and pulsatility index, which all consider end-diastolic velocities for the calculation and are, therefore, affected by the FHR. We apologize for overlooking Carvalho et al.'s description of a similar Doppler technique used in the descending aorta from 17 children with aortic coarctation2. In spite of several methodological and technical differences, including population, medical condition and targeted vessel studied, we fully agree with Dr Carvalho on the similarities between what they called ‘time to half peak systolic velocity’2 and our technique. However, we derived our impedance index from direct measurement of the spectral Doppler waveform and so, unlike Carvalho et al.2, we were unable to correlate our measurement with simultaneous electrocardiography. We consider that using electrocardiographic landmarks from systole and diastole and correlating them with the arterial Doppler systolic and diastolic velocities is not completely accurate, as there is a delay between the electrical component of the cardiac cycle and the corresponding blood flow velocity waveforms in a distant vessel. In the umbilical artery, this delay may be more pronounced than it is in the descending aorta due to the larger distance from the fetal heart. Although the maximum velocity in a given vessel is the direct result of the ventricular systole, the highest velocities are actually recorded during early cardiac diastole; therefore, the correct term to use in describing arterial Doppler flow patterns should be ‘maximum velocity’ rather than ‘peak systolic velocity’. J. C. Bustos*, W. Sepulveda , * Ultrasound Unit, Department of Obstetrics and Gynecology, San Juan de Dios Hospital, University of Chile School of Medicine, Santiago, Chile, Fetal Medicine Center, Clinica Las Condes, Santiago, Chile

P34.07: Ultrasound parameters of umbilical cord—reference values for normal pregnancy

weight for adverse perinatal outcome in a group of small-forgestational age (SGA) fetuses. Methods: Data were collected from 105 singleton and nonmalformed fetuses suspected of being SGA during the third trimester and with a confirmed birth weight below the 10th centile. At diagnosis, estimated fetal weight was customized according to maternal and fetal characteristics and middle cerebral artery pulsatility index and umbilical artery pulsatility index were recorded, and tranformed to Z-values. Adverse perinatal outcome was defined as umbilical artery pH at delivery ≤7.15, 5-minutes Apgar score ≤7, significant neonatal morbidity (seizures, respiratory distress syndrome, necrotising enterocolitis, grade II-III intraventricular hemorrhage, hypoxic-ischemic encephalopathy), need of intubation, neonatal intensive care unit admission or neonatal mortality. Results: The prevalence of adverse perinatal outcome in our group of SGA fetuses was 50.5%. While the area under the curve (AUC) for Z-customized estimated fetal weight was 0.7 (95% CI, 0.59–0.81), for Z-umbilical artery Doppler was 0.5 (95% CI, 0.39–0.63) and for Z-middle cerebral artery was 0.55 (95% CI, 0.44–0.68). Paired analysis between parameters demonstrated that customized standards UAC was significantly larger than for both Doppler indices. Overall, the sensitivity and specificity for 10th centile cut-off of customized estimated fetal weight was 67.4% and 64%, respectively. Conclusion: In SGA fetuses, customized standards are a better predictor for adverse perinatal outcome than middle cerebral artery or umbilical artery Doppler indices.