Fetal Middle Cerebral Artery Pulsatility Index Research Articles

Maternal vascular indices at 36 weeks' gestation in small and growth restricted fetuses.

To compare maternal vascular indices and hemodynamic parameters at 35-37 weeks' gestation, in pregnancies complicated by small for gestational age (SGA) fetuses and those with fetal growth restriction (FGR). This was a prospective observational non-intervention study in women with singleton pregnancies attending for a routine hospital visit at 35+0 to 36+6 weeks' gestation. The visit included recording of maternal demographic characteristics and medical history, vascular indices and hemodynamic parameters obtained by a non-invasive operator independent device, including pulse wave velocity, augmention index, cardiac output, stroke volume, central systolic and diastolic blood pressure, total peripheral resistance and fetal heart rate. Hypertensive disorders of pregnancy were excluded and the values in the SGA and FGR groups were compared between them and with unaffected pregnancies. Diagnosis of SGA was based on the birth of a baby with birthweight below the 10th percentile for gestational age. In FGR, in addition to a birthweight below the 10th percentile, at the 35-37 weeks scan Doppler studies had shown that the uterine artery or umbilical artery pulsatility index (PI) was above the 95th percentile for gestational age or the fetal middle cerebral artery PI was below the 5th percentile. In the 6,413 women included in the study there were 605 (9.4%) cases of SGA, 133 (2.1%) of FGR and 5,675 (88.5%) unaffected by SGA or FGR. Women with SGA or FGR, compared to unaffected pregnancies, had increased peripheral vascular resistance and reduced cardiac output. Central systolic and diastolic blood pressure were also increased, whereas aortic stiffness assessed by pulse wave velocity and augmentation index did not differ between affected and unaffected pregnancies. In the FGR, compared to the SGA group, central systolic and diastolic blood pressure were higher, whereas, heart rate was lower. In SGA and FGR pregnancies there are deranged maternal hemodynamic responses when these are compared to normal pregnancies. Mothers with FGR babies have higher central blood pressure compared to SGA ones, but it remains unclear whether these differences are driven by the size of the fetus or pathological fetal growth. This article is protected by copyright. All rights reserved.

Placental size at gestational week 27 and 37: The associations with pulsatility index in the uterine and the fetal-placental arteries

IntroductionFetal growth restriction is known to be related to decreased fetal and placental blood flow. It is not known, however, whether placental size is related to fetal and placental blood flow. We studied the correlations of intrauterine placental volume and placental-fetal-ratio with pulsatility index (PI) in the uterine arteries, fetal middle cerebral artery, and umbilical artery. MethodsWe followed a convenience sample of 104 singleton pregnancies, and we measured placental and fetal volumes using magnetic resonance imaging (MRI) at gestational week 27 and 37 (n = 89). Pulsatility index (PI) was measured using Doppler ultrasound. We calculated cerebroplacental ratio as fetal middle cerebral artery PI/umbilical artery PI and placental-fetal-ratio as placental volume (cm3)/fetal volume (cm3). ResultsAt gestational week 27, placental volume was negatively correlated with uterine artery PI (r = −0.237, p = 0.015, Pearson's correlation coefficient), and positively correlated with fetal middle cerebral artery PI (r = 0.247, p = 0.012) and cerebroplacental ratio (r = 0.208, p = 0.035). Corresponding correlations for placental-fetal-ratio were −0.273 (p = 0.005), 0.233 (p = 0.018) and 0.183 (p = 0.064). Umbilical artery PI was not correlated with placental volume. At gestational week 37, we found weaker and no significant correlations between placental volume and the pulsatility indices. ConclusionsOur results suggest that placental size is correlated with placental and fetal blood flow at gestational week 27.

Pre- and postnatal brain hemodynamics in pregnancies at term: correlation with Doppler ultrasound, birthweight, and adverse perinatal outcome

Purpose To elucidate the correlation between pre- and postnatal cerebral Doppler in pregnancies close to term and to explore whether they are associated with perinatal outcome. Materials and methods Prospective study on singleton pregnancies at 36–37 weeks of gestation. The primary outcome was a composite score of perinatal morbidity, while secondary outcomes were adverse intra-partum outcome and abnormal acid–base status. All pregnancies underwent ultrasound assessment of umbilical artery (UA), middle cerebral artery (MCA), uterine arteries (UtAs) pulsatility index (PI), and cerebroplacental ratio (CPR). At birth, neonatal MCA PI was measured 72 h from delivery and correlated with prenatal Doppler, primary and secondary outcomes. Fisher’s test and multivariate logistic regression analysis were used to analyze the data. Results One hundred and sixty-six fetuses with both pre- and postnatal Doppler assessment of the MCA were included in the study. The risk of composite perinatal morbidity was higher in fetuses (OR: 5.7, 95% CI 2.2–14.6) and newborns (OR: 4.1, 95% CI 1.8–9.6) with fetal MCA PI < 10th centile. Likewise, the incidence of abnormal acid–base status was higher both in fetuses (20 versus 4.2%, p = .026) and newborns (17.1 versus 3.2%, p = .001) with a low MCA PI before and at birth, respectively. At logistic regression analysis, fetal and neonatal MCAPI were independently associated with composite perinatal morbidity and abnormal acid–base status, but not with adverse intra-partum outcome. In small for gestational age (SGA) fetuses, the incidence of composite perinatal morbidity was higher in fetuses and new-borns presenting compared to those not presenting with an MCA PI < 10th centile (61.5 versus 20%, p = .003 and 52.6% versus 7.1%, p = .008, respectively), while such association was lost when considering non-SGA fetuses. Conclusion A low MCA PI is associated with adverse perinatal outcome in pregnancies at term and tends to persist after birth.

FETAL CARDIOVASCULAR PHYSIOLOGY AND POSTNATAL BRAIN DEVELOPMENT AND INJURY IN CRITICAL CONGENITAL HEART DISEASE

Fetal cerebrovascular resistance, as measured clinically by the middle cerebral artery pulsatility index (MCA-PI), has been shown to be associated with neurodevelopmental outcomes in critical congenital heart disease (CCHD). We investigated the relationship between fetal MCA-PI and postnatal, pre-

Fetal middle cerebral artery Doppler in late-term pregnancy: a predicting factor for failed induction of labor

Purpose: To study the role of fetal middle cerebral artery (MCA) Doppler evaluated prior to induction of labor in late-term pregnancies, in order to build an ultrasound-based predictive model for failed induction.Materials and methods: A prospective cohort study on 250 nulliparous women carrying singleton late-term pregnancies was conducted. Prior to induction, each patient underwent to an ultrasound evaluation for fetal MCA Doppler. Additional ultrasound parameters such as cervical length (CL), membranes thickness, amniotic fluid index, placental location, and estimated fetal weight (EFW) were collected. According to the type of response, women were divided into three groups: (A) responders within 24 h; (B) responders after 24 h, and (C) no responders.Results: Women who failed to enter active labor showed significantly higher fetal MCA pulsatility index (PI), longer CL and higher EFW. The estimated probability of logistic regression model combining the three variables achieved a sensitivity of 94.2% and a specificity of 86.36% (AUC, 0.926; 95% CI, 0.884 − 0.956, p < .0001) using as decision probability value the cut off >0.1838.Conclusions: In late-term pregnancies, an ultrasound-based model including cervical length, MCA PI, and EFW achieved a good accuracy in predicting those women who are likely to fail induction of labor.

Doppler indices of the umbilical and fetal middle cerebral artery at 18–40 weeks of normal gestation: A pilot study

BackgroundDoppler indices form an integral component of noninvasive evaluation of fetal well-being. There is paucity of information about normal obstetric Doppler indices, particularly from the Indian subcontinent. The aim of the study was to find the values of pulsatility index (PI), resistive index (RI) of umbilical artery (UA), and fetal middle cerebral artery (MCA) and calculate cerebro-placental ratio (CP ratio) for 18–40 weeks of normal gestation so that a reference range of these Doppler values can be postulated. Methods200 patients were enrolled in the study for color Doppler study of UA and MCA and were serially followed up at 4–6 weeks interval for Doppler indices. Angle-independent Doppler indices like PI and RI for MCA and UA were obtained during each examination. CP ratio was calculated in each case. All the cases were followed up till delivery and the perinatal outcome was recorded. Results & ConclusionThe fetal MCA PI and RI showed a parabolic curve with plateau at 28–30 weeks of gestation. A significant correlation was noted between MCA PI and RI with gestational age. UA PI and RI showed a gradual fall over the gestational age with a strong negative correlation. There was a significant correlation between MCA PI and UA PI with their respective RI values. CP ratio has also shown a parabolic curve with turning point at 31–32 weeks of gestation. A significant correlation was noted between CP ratio and gestational age. CP ratio also showed a minimal positive correlation with MCA PI and a strong negative correlation with UA PI.

An integrated model with classification criteria to predict small-for-gestational-age fetuses at risk of adverse perinatal outcome.

To develop an integrated model with the best performing criteria for predicting adverse outcome in small-for-gestational-age (SGA) pregnancies. A cohort of 509 pregnancies with a suspected SGA fetus, eligible for trial of labor, was recruited prospectively and data on perinatal outcome were recorded. A predictive model for emergency Cesarean delivery because of non-reassuring fetal status or neonatal acidosis was constructed using a decision tree analysis algorithm, with predictors: maternal age, body mass index, smoking, nulliparity, gestational age at delivery, onset of labor (induced vs spontaneous), estimated fetal weight (EFW), umbilical artery pulsatility index (PI), mean uterine artery (UtA) PI, fetal middle cerebral artery PI and cerebroplacental ratio (CPR). An adverse outcome occurred in 134 (26.3%) cases. The best performing predictors for defining a high risk for adverse outcome in SGA fetuses was the presence of a CPR < 10th centile, a mean UtA-PI > 95th centile or an EFW < 3rd centile. The algorithm showed a sensitivity, specificity and positive and negative predictive values for adverse outcome of 82.8% (95% CI, 75.1-88.6%), 47.7% (95% CI, 42.6-52.9%), 36.2% (95% CI, 30.8-41.8%) and 88.6% (95% CI, 83.2-92.5%), respectively. Positive and negative likelihood ratios were 1.58 and 0.36. Our model could be used as a diagnostic tool for discriminating SGA pregnancies at risk of adverse perinatal outcome.

Fetal Brain Hemodynamic Changes in Intrauterine Transfusion: Influence of Needle Puncture Site

Objectives: Previous research has suggested that hemodynamic changes after in utero transfusion may be related to fetal stress. We tested the hypothesis that these hemodynamic changes are more pronounced when the needle is inserted in the fetal abdomen compared with the umbilical cord root. Methods: Most intrauterine transfusions are performed by inserting a needle either in the umbilical cord root at the placental surface (PCI) or in the intrahepatic portion of the umbilical vein (IHV). We analyzed prospectively collected data of all intrauterine blood transfusions (IUT) for fetal alloimmune anemia (from 2000 to 2003), for which complete data were available on needling site and middle cerebral artery (MCA) Doppler flow velocity measurements before and immediately after the procedure. Results: Data of 57 IUTs were included. In 32 patients, the transfusion was performed through the PCI and in 25 patients through the IHV. Mean pulsatility index (PI) in the PCI group was 2.0 before and 1.7 after IUT (p = 0.011), and in the IHV group 1.9 before and 1.5 after IUT (p = 0.001). In both groups, MCA PI decreased significantly, but there was no difference in decrease between the two groups (p = 0.99). Conclusions: In anemic fetuses undergoing transfusion, the observed fetal brain hemodynamic changes were independent of the site of needle insertion. The decrease in fetal MCA PI is therefore likely to be caused by the volume expansion.

Fetal Middle Cerebral Artery Doppler Waveforms in Twin–Twin Transfusion Syndrome

The aim of this study was to compare the fetal middle cerebral artery (MCA) Doppler waveforms in growth-retarded twin fetuses with (n = 11) and without (n = 24) twin–twin transfusion syndrome (TTTS). Umbilical artery (UA) and fetal MCA Doppler velocity waveforms were recorded on admission. The mean values of the UA pulsatility index (PI) of smaller twin fetuses with and without TTTS were significantly higher than those of normal singleton pregnancies. The mean values of the MCA PI of smaller twin fetuses in the TTTS group (+0.7 ± 1 SD) were significantly higher than those of normal singleton pregnancies on admission, and these levels did not markedly change following amniocentesis. On the other hand, the values of the MCA of the growth-retarded fetuses without TTTS (–0.9 ± 1 SD) were significantly lower than those of normal singleton pregnancies. Our findings suggest that measurement of fetal MCA PI is a useful method to assess growth-retarded fetuses in monochorionic twin pregnancies.

Nitrous oxide inhalation: Effects on maternal and fetal circulations at term

To evaluate the hemodynamic effects of nitrous oxide inhalation in normal term pregnancy. Twenty healthy term pregnant women were given 30% nitrous oxide in pure oxygen for 2 minutes, and the hemodynamics were assessed by pulsed-wave color Doppler velocimetry of the uterine and internal carotid artery of the mother and the umbilical and middle cerebral artery of the fetus. Each vessel was assessed separately, allowing a 5-minute wash-out period between the inhalations. The measurements were continued for 2 minutes after the inhalation, and the pulsatility index (PI) was determined at 1-minute intervals. The maternal heart rate and blood pressure (BP) were recorded before and after inhalation; fetal well-being was confirmed with cardiotocography. Analysis of variance for repeated measurements and paired-sample t test were used for statistical analysis. A significant decrease in the PI of the maternal internal carotid artery was observed after 2-minutes of inhalation (from 0.83 +/- 0.22 to 0.71 +/- 0.20; P < .001). The uterine artery PI and maternal BP and heart rate were not affected by nitrous oxide. A significant decrease was evident even in the fetal middle cerebral artery PI (from 1.37 +/- 0.27 to 1.22 +/- 0.17; P = .02). The umbilical artery PI remained unchanged. Both maternal and fetal central vascular resistance were decreased by 30% nitrous oxide inhalation. So far, no adverse effects to mother or fetus have been demonstrated in clinical practice. However, preterm fetuses are susceptible to intracranial hemorrhage, and the cerebral hyperemia by nitrous oxide might increase the risk of hemorrhage in these fetuses. This hypothesis requires further investigation.