Doppler Resistance Index Research Articles

Uterine artery blood flow in the periimplantation period in embryo transfer cycles

To assess the role of the uterine artery blood flow in the prediction of implantation in women undergoing embryo transfer during the periimplantation period. A total of 233 couples were included in this prospective study. All patients had embryo transfer, 125 were performed in in-vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) and 108 in cryo cycles. Ultrasound measurements were performed immediately before transfer. The pulsatility index (PI), Resistance index (RI) and the peak systolic velocity (PSV) were measured in both uterine arteries using endovaginal ultrasound. In IVF/ICSI cycles the doppler parameters PI (2.48 vs. 2.15), RI (0.78 vs. 1.30) and PSV (60 vs. 63) did not differ significantly between the pregnant and non-pregnant group. The pregnancy rate per transfer was similar in women showing an unilateral (24%), bilateral (33%) or no (27%) notch in the uterine blood flow. In cryo cycles the uterine artery blood flow parameters PI (3.2 vs. 3.0), RI (0.9 vs. 0.9) and PSV (53.2 vs. 51.2) did not differ either between pregnant and not pregnant patients. Previous studies were aiming at the measurement of arterial doppler parameters during the follicular phase which may not be adequate for the prediction of implantation. However, our results show that doppler studies during the early luteal phase of assisted reproductive technology cycles are not indicative for the likelihood of pregnancy, too.

Resistive Index of Prostate Capsular Arteries: A Newly Identified Parameter to Diagnose and Assess Bladder Outlet Obstruction in Patients with Benign Prostatic Hyperplasia

We evaluated the association of the resistive index of the prostate capsular arteries and bladder outlet obstruction severity in men with benign prostatic hyperplasia. A total of 74 patients histologically diagnosed with benign prostatic hyperplasia were ultimately enrolled in this prospective study. Urodynamics were performed by a urologist to determine bladder outlet obstruction. Baseline parameters measured in patients with benign prostatic hyperplasia were the prostate capsular artery resistive index, International Prostate Symptom Score, quality of life score, total prostate and transition zone volume, and the transition zone index. ROC curves were produced to calculate the ROC AUC and evaluate the diagnostic performance of the prostate capsular artery resistive index, International Prostate Symptom Score, obstructive symptoms, total prostate and transition zone volume, and the transition zone index for bladder outlet obstruction. Significant difference between patients with and without bladder outlet obstruction was observed in the resistive index, which showed the highest coefficient with the degree of obstruction (r = 0.712, p <0.0001). At a cutoff of 0.69 the resistive index distinguished patients with and without bladder outlet obstruction with 78% sensitivity and 86.4% specificity. The prostate capsular artery resistive index had the maximum AUC of 0.823. The prostate capsular artery resistive index is significantly higher in patients with benign prostatic hyperplasia related bladder outlet obstruction than in those without such obstruction. The resistive index might serve as a novel indicator to diagnose and assess bladder outlet obstruction in patients with benign prostatic hyperplasia.

Doppler Study of the Fetal Vertebral Artery in Small for Gestational Age Fetuses With Intrauterine Growth Restriction

The purposes of this study were to evaluate the Doppler resistive index of the fetal vertebral artery in small for gestational age (SGA) fetuses and to examine the ability of the vertebral artery resistive index in the diagnosis of intrauterine growth restriction (IUGR). A total of 437 Doppler examinations of the vertebral and umbilical artery resistive indices were performed in 437 fetuses between 26 and 41 weeks' gestation. According to birth weight, fetuses were classified into 5 groups: 1, above the 10th percentile; 2, between the 10th and 5th percentiles; 3, between the 5th and 3rd percentiles; 4, below the 3rd percentile; and 5, below the 3rd percentile with an umbilical artery resistive index above the 95th percentile. Subsequently, vertebral artery resistive index values were converted into multiples of the median, and box and whisker charts were generated to evaluate differences. Finally, receiver operating characteristic curves were calculated to assess the accuracy of the vertebral artery resistive index for predicting IUGR and a low Apgar score. Compared to normally grown fetuses, vertebral artery resistive index values were lower in fetuses with birth weight below the 3rd percentile, and this difference was greater in fetuses with birth weight below the 3rd percentile and Doppler anomalies of the umbilical artery. The receiver operating characteristic analysis showed that the vertebral artery resistive index diagnosed SGA fetuses and low Apgar scores poorly. However, it performed better in cases of severe IUGR with high umbilical artery resistive index values. Preliminary data show that the vertebral artery resistive index diminishes in growth-restricted SGA fetuses. Doppler examination of the vertebral artery seems to identify a group of fetuses with brain sparing and severe IUGR.

WISE 2005: responses of women to sublingual nitroglycerin before and after 56 days of 6° head-down bed rest

This study tested the hypothesis that cardiovascular effects of sublingual nitroglycerin (NG) would be exaggerated after 56 days of 6° head-down bed rest (HDBR) in women, and that an aerobic and resistive exercise countermeasure (EX, n = 8) would reduce the effect compared with HDBR without exercise (CON, n = 7). Middle cerebral artery maximal blood flow velocity (CBFV), cardiac stroke volume (SV), and superficial femoral artery blood flow (Doppler ultrasound) were recorded at baseline rest and for 5 min following 0.3 mg sublingual NG. Post-HDBR, NG caused greater increases in heart rate (HR) in CON compared with EX (+24.9 ± 7.7 and +18.8 ± 6.6 beats/min, respectively, P < 0.0001). The increase in HR combined with reductions in SV to maintain cardiac output. Systolic, mean, and pulse pressures were reduced 5-10 mmHg by NG, but total peripheral resistance was only slightly reduced at 3 min after NG. Reductions in CBFV of -12.5 ± 3.8 cm/s were seen after NG, but a reduction in the Doppler resistance index suggested dilation of the middle cerebral artery with no differences after HDBR. The femoral artery dilated with NG and blood flow was reduced ∼50% with the appearance of large negative waves suggesting a marked increase in downstream resistance, but there were no effects of HDBR. In general, responses of women to NG were not altered by HDBR; the greater increase in HR in CON but not EX was probably a consequence of cardiovascular deconditioning. These results contrast with the hypothesis and a previous investigation of men after HDBR by revealing no change in cardiovascular responses to exogenous nitric oxide.

Relationship of first‐trimester uterine artery Doppler to late stillbirth

The aim of this study was to investigate if increased first-trimester uterine artery Doppler resistance indices (RI) are related to stillbirth. Uterine artery Doppler indices were assessed prospectively during a routine first-trimester ultrasound scan. Patients were categorised as having a high uterine artery mean Doppler RI if the index was above the 90th centile for gestation. Stillbirth outcomes were ascertained from a mandatory national register of pregnancy losses. High RI uterine artery Doppler (>90th centile) was an independent risk factor for late (≥ 34 weeks) but not early stillbirth, with a hazard ratio of 2.61 (95% CI 1.13-6.03). The inclusion of uterine artery Doppler indices into Cox proportional hazard model negated the influence of conventional risk factors for stillbirth, such as parity, maternal age and body mass index (BMI), but not Afro-Caribbean ethnicity or smoking. High first-trimester uterine artery Doppler RI is associated with late stillbirth after 34 weeks' gestation. This association supersedes those of conventional risk factors such as maternal age, parity and BMI, implying that these factors result in an increased risk of stillbirth by causing placental dysfunction.

Role of Second-Trimester Uterine Artery Doppler in Assessing Stillbirth Risk

To estimate the association between uterine artery Doppler indices and stillbirth in routinely screened populations. Second-trimester uterine artery Doppler indices at 19 to 23 weeks of gestation were obtained from a large cohort of women. Pregnancy losses recorded on a mandatory national register were cross-linked to the Doppler database. Kaplan-Meier curves were constructed for the risk of stillbirth based on the uterine artery Doppler resistance indices. Logistic regression analysis was used to assess the influence of uterine artery Doppler indices and other more conventional risk factors on the likelihood of stillbirth. Data were available from 15,835 women with 144 stillbirths (9.1 stillbirths per 1,000 births). Kaplan-Meier analysis showed that the risk of stillbirth (39.41 per 1000) in women with uterine artery Doppler indices greater than the 90th percentile was sevenfold higher (95% confidence interval 4.81-9.57) than the reference population (5.36 per 1000) with Doppler indices less than or equal to the 90th percentile. The positive predictive and negative predictive values for the 90th percentile uterine artery Doppler cutoff were 3.79% and 99.46%, respectively [corrected] The sensitivities of the 90th, 95, and 99th percentile uterine artery Doppler resistance index cut-offs for the sensitivity of stillbirth were 46.2%, 35.4%, and 15.4%, respectively. Conventional risk factors for term stillbirth such as ethnicity, body mass index (BMI), and smoking no longer contributed to stillbirth risk when uterine artery Doppler indices were included in multivariable logistic regression analysis. Elevated second-trimester Doppler indices, a proxy for impaired placentation, are more strongly associated with stillbirth than conventional risk factors. Risk factors such as ethnicity, maternal age, BMI, and smoking contribute to risk of term stillbirth through uteroplacental dysfunction. II.

Hemorrhagic Shock in Polytrauma Patients: Early Detection with Renal Doppler Resistive Index Measurements

Hemorrhagic Shock in Polytrauma Patients: Early Detection with Renal Doppler Resistive Index Measurements

Perinatal outcomes of fetal growth restriction between late preterm and term birth infants

Objective To estimate the absolute increase in the risk for adverse neonatal outcomes of fetal growth restriction between late preterm and term birth and to identify risk factors for neonatal morbidity among late preterm and term birth infants. Methods A retrospective review of 2,954 singleton infant between 34 and 42 weeks of gestation born at our hospital over the 5 years were enrolled and they were divided into four groups as late preterm small for gestational age (SGA), late preterm adequate for gestational age (AGA), term SGA and term AGA, respectively. The prenatal ultrasonographic findings between SGA and AGA in late preterm birth were assessed. Maternal and neonatal complications were compared with SGA and AGA between late preterm and term birth infants. The statistical analyses for frequencies and relative risks in each group were calculated by SPSS ver. 19.0. Results In prenatal evaluation between SGA and AGA in late preterm birth, amniotic fluid volume, abdominal circumference and umbilical artery Doppler resistance index value were different significantly ( P<0.001). Preeclampsia and oligohydramnios were found more common in SGA of late preterm birth compared with AGA of term birth. Jaundice, respiratory distress syndrome, necrotizing enterocolitis, sepsis, congenital anomalies, hypoglycemia, and germinal matrix`s hemorrhage, occurred more frequent in SGA of late preterm birth than in AGA of term birth. Conclusion Not only adequate prenatal evaluation and obstetrical decision-making but also long-term evaluation are needed to improve perinatal outcomes of growth restricted infants in late preterm birth.

Doppler resistive index to reflect regulation of renal vascular tone during sepsis and acute kidney injury

IntroductionRenal resistive index (RI), determined by Doppler ultrasonography, directly reveals and quantifies modifications in renal vascular resistance. The aim of this study was to evaluate if mean arterial pressure (MAP) is determinant of renal RI in septic, critically ill patients suffering or not from acute kidney injury (AKI).MethodsThis prospective observational study included 96 patients. AKI was defined according to RIFLE criteria and transient or persistent AKI according to renal recovery within 3 days.ResultsMedian renal RIs were 0.72 (0.68-0.75) in patients without AKI and 0.76 (0.72-0.80) in patients with AKI (P=0.001). RIs were 0.75 (0.72-0.79) in transient AKI and 0.77 (0.70-0.80) in persistent AKI (P=0.84). RI did not differ in patients given norepinephrine infusion and was not correlated with norepinephrine dose. RI was correlated with MAP (ρ= -0.47; P=0.002), PaO2/FiO2 ratio (ρ= -0.33; P=0.04) and age (ρ=0.35; P=0.015) only in patients without AKI.ConclusionsA poor correlation between renal RI and MAP, age, or PaO2/FiO2 ratio was found in septic and critically ill patients without AKI compared to patients with AKI. These findings suggest that determinants of RI are multiple. Renal circulatory response to sepsis estimated by Doppler ultrasonography cannot reliably be predicted simply from changes in systemic hemodynamics. As many factors influence its value, the interest in a single RI measurement at ICU admission to determine optimal MAP remains uncertain.

389: Placental biometry and intraplacental villous artery Doppler as predictors of placentally-mediated pregnancy complications

389: Placental biometry and intraplacental villous artery Doppler as predictors of placentally-mediated pregnancy complications

13 ULTRASOUND EVALUATION OF FETAL AND PLACENTAL DEVELOPMENT IN SOMATIC CELL NUCLEAR TRANSFER AND ARTIFICIAL INSEMINATION BOVINE PREGNANCIES

Since the first success in sheep, the production of viable cloned offspring by somatic cell nuclear transfer (SCNT) is still doomed by a high incidence of pregnancy failure. In cattle, most gestation losses initially take place during the peri-implantation period. Then, abnormal placentation associated with fetal overgrowth (abnormal offspring syndrome) occurs in late pregnancy. As a consequence, IETS recommendations include regular ultrasound evaluation of SCNT pregnancies, with qualitative ultrasound evaluation of the placentomes, fetal movements and fluids being proposed. The objective of this study was to evaluate the use of new, quantitative parameters for the assessment of feto-placental development in AI and SCNT bovine pregnancies. Twenty-two heifers of 4 different breeds were used as SCNT recipients and 11 Holstein heifers were used as AI controls (C). All SCNT fetuses were produced as previously published in the laboratory, using the same fibroblast donor. Animals were scanned every 2 weeks from Day 150 using a Voluson-i (GE Medical Systems) with a transabdominal multifrequency probe (2.2 to 6.5 MHz), allowing automatic 3D volume and Doppler acquisition. Each time, 7 placentomes were scored from 0 to 3 according to echogenicity, general appearance and degree of oedema and their 2D surface was measured. Fetal intercostal width (ICW) was measured in a coronal view just behind the heart. Doppler velocimetry indices, pulsatility index (PI) and resistance index (RI) of one of the two fetal umbilical arteries were obtained and the diameters of the umbilical vessels were measured (UD). The 3D power Doppler was performed to obtain vascular index (VI), flow index (FI) and vascular flow index (VFI). Data were analysed by ANOVA with GraphPad Prism®. So far, 27 heifers have either delivered (n = 10 SCNT and 7 C) or pregnancies have been terminated because of abnormal offspring syndrome (n = 10 SCNT). One thousand five hundred and 197 placentomes have been analysed for 2D and 3D analyses, respectively. The mean placentome score is significantly higher (less normal) in SCNT compared with C (P &lt; 0.0001) but does not vary according to gestational age. The placentome surface is also significantly larger in SCNT vs C (P &lt; 0.0001) but also in SCNT that did not go to term vs those that were alive at birth (P &lt; 0.002). Fetal ICW and UD are consistently larger in SCNT vs C (P &lt; 0.0001) at all stages of pregnancy and there is a significant correlation (r2 = 0.81) between ICW at 15 days before term and birth weight. The PI and RI were not different between SCNT and C. Intra-operator reproducibility of 3D analyses was very high (intra-class correlation coefficient: 80 to 95% for a 95% confidence interval). There was no significant difference for VI, FI, or VFI between SCNT and C. Ongoing work taking into account pregnancy outcomes indicates that placentome scores are useful indicators of pregnancy outcome in SCNT pregnancies. In contrast, the abnormal vascularization observed by histology in SCNT placentomes does not appear to be accompanied by abnormal placental blood flow when analysed using quantitative 3D Doppler. This project received financial support from ANR (ref. PCS-09-GENM-022).

Hemorrhagic Shock in Polytrauma Patients: Early Detection with Renal Doppler Resistive Index Measurements

To investigate whether renal Doppler resistive index (RI) changes occur early during posttraumatic bleeding and may be predictive of occult hypoperfusion-and thus hemorrhagic shock-in patients with polytrauma. This study was approved by the institutional ethics committee, and informed consent was obtained from all patients. The renal Doppler RI was measured in 52 hemodynamically stable adult patients admitted to the emergency department (ED) because of polytrauma. Renal Doppler RI, hemoglobin, standard base excess, lactate, systolic blood pressure, pH, heart rate, and inferior vena cava diameter values were recorded at admittance and correlated with outcome (progression or nonprogression to hemorrhagic shock). Logistic regression analysis was performed to assess the risk factors for progression to hemorrhagic shock. Twenty-nine patients developed hemorrhagic shock, and 23 did not. At univariable analysis, the hemorrhagic shock group, as compared with the nonhemorrhagic shock group, had higher renal Doppler RI (mean, 0.80 ± 0.10 [standard deviation] vs 0.63 ± 0.03; P < .01), injury severity score (mean, 36 ± 11 vs 26 ± 5; P < .01), and standard base excess (mean, -4.0 mEq/L ± 4 vs 1 mEq/L ± 3; P = .04) values. At logistic regression analysis, a renal Doppler RI greater than 0.7 (vs less than or equal to 0.7) was the only independent risk factor for progression to hemorrhagic shock (odds ratio, 57.8; 95% confidence interval: 10.5, 317.0) (P < .001). In polytrauma patients who are hemodynamically stable at admittance to the ED, renal cortical blood flow redistribution occurs very early in response to occult bleeding and might be noninvasively detected by using the renal Doppler RI. A renal Doppler RI greater than 0.7 is predictive of progression to hemorrhagic shock in polytrauma patients.

Prevalence of maternal cardiac defects in women with high‐resistance uterine artery Doppler indices

To compare the prevalence of previously undiagnosed cardiac structural abnormalities in pregnant women with normal- and high-resistance midtrimester uterine artery Doppler indices. Maternal transthoracic echocardiography was undertaken in asymptomatic pregnant women after uterine artery Doppler screening for pre-eclampsia at 21-23 weeks' gestation. Women with a mean uterine artery pulsatility index above the 90(th) centile (1.25) for the local population (multiethnic, socially diverse and migrant) were considered to have high-resistance uteroplacental blood flow indices. The prevalence of newly diagnosed cardiac structural defects in these women was recorded. A total of 491 women underwent echocardiography, of whom 205 had high-resistance uterine artery blood flow indices. There were nine previously undiagnosed, functionally significant cardiac defects in the high-resistance uterine artery blood flow group and only one, functionally insignificant cardiac defect in the normal-resistance group (P = 0.005; relative risk = 12.6, 95% confidence interval, 1.60-98.34). Multiple regression analysis demonstrated that both uterine artery Doppler indices (P = 0.024) and ethnicity (P = 0.048) contributed independently towards a higher prevalence of cardiac defects. The prevalence of previously undiagnosed maternal cardiac structural abnormalities is significantly increased in women with high midtrimester uterine artery Doppler resistance indices. This observation has important consequences for the current and long-term medical care provided to these patients. Detailed maternal cardiac assessment with echocardiography may be required in migrant women with high uterine artery Doppler indices.

Intrauterine Growth Restriction (IUGR) Risk Decision Based on Support Vector Machines

This paper studies the risk of intrauterine growth restriction (IUGR) using support vector machines (SVM). A structured and globally optimized SVM system may be preferable procedure in the identification of IUGR fetus at risk. The IUGR risk is estimated in two stages: in the first stage, noninvasive Doppler pulsatility index (PI) and resistance index (RI) of umbilical artery (UA), middle cerebral artery (MCA) and ductus venosus (DV) and amniotic fluid index (AFI) are retrospectively analyzed and the Doppler indices are applied to the SVM system to make a diagnosis decision on the fetal wellbeing as ”reactive” or “nonreactive and/or acute fetal distress (AFD)” on the nonstress test (NST) (training data). In the second stage (testing data), the decision is validated by the NST (target value). Experiments are performed on previously collected data. Fortyfour preterm with IUGR and without IUGR pregnancies before 34 weeks gestation are considered.The nonparametric Bayes-risk decision rule, k-nearest neighbor (k-NN), is used for comparison. It is observed that the SVM system is proven to be useful in predicting the expected risk in IUGR cases in this small population study. The PI and RI values of UA, MCA and DV are also effective in distinguishing IUGR at risk.

OP37.04: Sensitivity of the higher, lower and mean second trimester uterine artery Doppler resistance index in screening for pre‐eclampsia

OP37.04: Sensitivity of the higher, lower and mean second trimester uterine artery Doppler resistance index in screening for pre‐eclampsia

The role of Doppler ultrasonography and resistive index in the diagnosis and treatment of benign prostate hyperplasia

The role of Doppler ultrasonography and resistive index in the diagnosis and treatment of benign prostate hyperplasia

Maternal cardiac function in fetal growth restriction and preeclampsia

IntroductionInadequate trophoblast invasion is a common aetiological factor for both preeclampsia (PE) and fetal growth restriction (FGR). Preterm PE is known to be associated with significant cardiac diastolic dysfunction and...

Effect of antihypertensive therapy with α‐methyldopa on uterine artery Doppler in pregnancies with hypertensive disorders

Antihypertensive drugs lower blood pressure by direct vascular effects or central vasodilatory mechanisms. Their effect on uterine artery Doppler resistance indices in hypertensive disorders of pregnancy is uncertain. This study aimed to evaluate the impact of antihypertensive therapy with alpha-methyldopa on maternal uterine artery Doppler pulsatility index (PI) and resistance index (RI) in women presenting with hypertensive disorders of pregnancy. This was a cross-sectional study of 51 women with pre-eclampsia, 29 with gestational hypertension and 80 matched normotensive controls. Uterine artery PI and RI were measured at recruitment (between 24 and 40 weeks' gestation) and, in the hypertensive groups, 24-48 h after starting alpha-methyldopa. Differences between mild and severe, and between early- and late-onset pre-eclampsia were compared using the Mann-Whitney test. The Wilcoxon rank sum test was used to compare measurements before and after treatment. Prior to treatment, uterine artery PI and RI were significantly higher in women with pre-eclampsia compared with those with gestational hypertension and controls (P < 0.0001). The median uterine artery PI multiple of the median (MoM) was significantly higher (P < 0.0001) in early-onset than in late-onset pre-eclampsia (1.83 (range, 0.88-3.65) vs. 1.19 (range, 0.91-1.72)) and in severe compared with mild disease (2.26 (range, 2.02-3.65) vs. 1.29 (range, 0.88-2.9)). Uterine artery PI- and RI-MoMs in both pre-eclampsia and gestational hypertension, before and after 34 weeks' gestation, were not affected by alpha-methyldopa treatment. Antihypertensive therapy using alpha-methyldopa in women presenting with hypertensive disorders of pregnancy has no significant effect on uterine artery resistance to blood flow, suggesting that it does not impair uteroplacental circulation in these cases.

Sensitivity of higher, lower and mean second‐trimester uterine artery Doppler resistance indices in screening for pre‐eclampsia

First-trimester Doppler studies have reported that the lower uterine artery (UtA) resistance index (RI) is better for the prediction of pre-eclampsia (PE) than is either the mean or higher indices. The aim of this study was to determine if this relationship is true in the second trimester. This was a retrospective study of 24 859 singleton pregnancies. During the study period second-trimester UtA Doppler assessment was routinely available to all nulliparous women and to parous women at increased risk of PE. UtA-RI was obtained at the time of the anomaly scan. Receiver-operating characteristics curves for the lower, mean and higher UtA-RI for the prediction of PE were calculated. There were 1037 cases of PE. There were significant associations between UtA-RI and PE, the association being stronger for early and preterm than late or term PE. There was no significant difference in the strength of the association between lower, mean and higher RI with PE at any gestation. Performance of UtA-RI in predicting PE is no different for the lower, higher or mean RI of the two UtAs. The most likely explanation for the discrepancy with first-trimester studies is that the placental-side effect on Doppler indices may change with advancing gestational age and progressive trophoblast development and invasion.

Fetal Aortic-cerebral Doppler Resistance Index Ratio: An Indicator of Physiologic Blood Flow Distribution

Abstract Identical hemodynamic impedance and constant ratio of the fetal descending aorta and middle cerebral artery of uncomplicated pregnancies at term. Fetal aortic-cerebral Doppler resistance index ratio: An indicator of physiologic blood flow distribution. Objective To interpret the physiologic fetal arterial blood flow distribution by relating the vascular impedance of the fetal descending aorta (DA) and middle cerebral artery (MCA) and to establish the reference ranges for the aortic-cerebral Doppler resistance index ratio (ACRI). Study design Ninety-six patients with uncomplicated pregnancies were recruited for the cross-sectional assessment of the Doppler resistance index (RI) in the fetal DA and MCA between the 38rd and 40th weeks of gestation. The normal ranges of the ACRI were calculated. A cut-off value was designed to facilitate the clinical application of the ACRI. Results Between the 38th and 40th weeks of gestation in normal pregnancies the ACRI of healthy fetuses is constant, the overall mean is: 1.062 (+/– 0.087). A single cut-off value of 1.2 is recommended to assist separating normal and pathologic arterial blood flow patterns. Conclusion The normal ACRI reflects the identical vascular resistance of the descending aorta and the cerebral vessels, which maintains the physiologic fetal central arterial blood flow. Additional clinical studies are necessary to assess the diagnostic efficacy of the abnormal ACRI (&gt;1.2) as a potentially useful marker of the centralized arterial circulation indicating the early stage of fetal hypoxemic jeopardy.