Prognostic value of umbilical-middle cerebral artery pulsatility index ratio in fetuses with growth restriction

Sex-specific reference ranges of cerebroplacental and umbilicocerebral ratios: longitudinal study

OBJECTIVES

Observational studies have shown that low cerebroplacental ratio (CPR) values predict an increased risk of adverse perinatal outcome. The inverse ratio, i.e. the umbilicocerebral ratio (UCR), has been suggested to be a better predictor as it rises with increasing degree of fetal compromise. However, longitudinal reference ranges for UCR have not been established, and whether gestational-age-dependent changes in CPR or UCR differ between male and female fetuses has not been studied. Thus, the aims of this study were to investigate sex-specific, gestational-age-associated serial changes in CPR and UCR during the second half of pregnancy and to establish longitudinal reference ranges.

METHODS

This was a secondary analysis of prospectively collected data from a dual-center longitudinal observational cohort study of low-risk singleton pregnancies. Doppler blood-flow velocity waveforms were obtained serially from the umbilical artery (UA) and fetal middle cerebral artery (MCA) from 19-41 weeks' gestation, and pulsatility indices (PIs) were determined. CPR and UCR were calculated as the ratios MCA-PI/UA-PI and UA-PI/MCA-PI, respectively. The course and outcome of pregnancies were recorded, and the sex of the fetus was determined after delivery. Reference intervals for CPR and UCR were constructed using multilevel modeling, and gestational-age-specific Z-scores in male and female fetuses were compared.

RESULTS

Of a total of 299 pregnancies enrolled, 284 (148 male and 136 female fetuses) were included in the final analysis, and 979 paired measurements of UA-PI and MCA-PI were used to construct sex-specific longitudinal reference intervals. The relationship of both CPR and UCR with gestational age was U-shaped, but in opposite directions. There was a small but significant difference in Z-scores of CPR and UCR between male and female fetuses throughout the second half of pregnancy (P = 0.007).

CONCLUSIONS

We have established longitudinal reference ranges for CPR and UCR suitable for serial monitoring, with the possibility of refining assessment by using fetal sex-specific ranges and conditioning by a previous measurement. The clinical significance of such refinements needs further evaluation. © 2019 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of the International Society of Ultrasound in Obstetrics and Gynecology.

The effect of nifedipine tocolysis on Doppler indices of the uterine and umbilical arteries

PURPOSE

The aim of this study was to evaluate the effect of oral nifedipine on Doppler indices of the uterine artery (UtA) and umbilical artery (UA) before and 24 hours, 48 hours, and 1 week after tocolytic treatment.

METHODS

This was a prospective, self-controlled, cohort study of 65 pregnant women undergoing nifedipine tocolysis. Doppler assessment of the UtA and UA was performed before treatment and 24 hours, 48 hours, and 1 week after the initial 4 doses of 10 mg of oral nifedipine, administered at 20-minute intervals. The maintenance dosage was 20 mg of oral nifedipine administered every 6 hours for 48 hours, for a total dose of 80 mg/day.

RESULTS

There was a decrease in the 24-hour values of the UA pulsatility index, resistance index (RI), systolic-diastolic (S:D) ratio, right UtA pulsatility index, RI, S:D ratio, and left UtA RI and S:D ratio with nifedipine therapy in comparison with the values recorded prior to nifedipine therapy. However, these differences were not statistically significant. There were no statistically significant differences between the data recorded prior to nifedipine administration and those obtained at 48 hours and 1 week after treatment.

CONCLUSIONS

Oral nifedipine is a safe tocolytic agent with no long-term effect on fetomaternal circulation in pregnant women at risk of preterm delivery.

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.

Fetal cerebral hemodynamic in gestational diabetic versus normal pregnancies: a Doppler velocimetry of middle cerebral and umbilical arteries

Gestational diabetes mellitus (GDM) is one of the most common complications in pregnancies. Evaluating other conditions, including intra uterine growth restriction and pre-eclampsia, some studies have shown significant changes in blood flow velocity of fetal middle cerebral artery (MCA). Our study is one of the few that has aimed to assess the effects of GDM on Doppler parameters of the fetal MCA and umbilical artery (UA) and to compare with normal pregnancies. This cross-sectional study was performed on 66 pregnant women, including 33 women with GDM and the others without it, in Akbar-Abadi University Hospital in Tehran, Iran during 2010-2011. Peak systolic and diastolic velocities, pulsatility index (PI), resistance index (RI) and systolic diastolic ratio (SD) were recorded in UA as well as both right and left fetal MCAs for every recruited pregnant women by means of Doppler ultrasonography. The mean gestational age at the time of examination was 34.45 (SD = 2.62) weeks in GDM group. Although all of the measured Doppler parameters had higher values in GDM pregnancies, the differences were not significant between two groups of study; except for the left fetal MCA-PI, which was significantly higher in GDM group [2.07 (SD = 0.07) vs. 1.85 (SD = 0.74), P = 0.03]. Our results show that gestational diabetes may contribute to an elevated PI in the fetal MCA. Although there is not yet strong proof for the effect of GDM on the fetal brain hemodynamics, the significant higher MCA-PI warrants more attention towards better controlling of the hyperglycemia during pregnancy.

Doppler velocimetry of the fetal middle cerebral artery and other parameters of fetal well-being in neonatal survival during pregnancies with placental insufficiency

OBJECTIVE

To study the Doppler velocimetry of the fetal middle cerebral artery in pregnancies complicated by placental insufficiency, and to verify its role in the prognosis of neonatal survival.

METHODS

This was a prospective study of 93 pregnant women with diagnosis of placental insufficiency detected before the 34(th) week of pregnancy. Placental insufficiency was characterized by abnormal umbilical artery (UA) Doppler (> 95(th) percentile). The following parameters were analyzed: umbilical artery (UA) pulsatility index (PI); middle cerebral artery (MCA) PI; brain-placenta ratio--BPR (MCA-PI/UA-PI); MCA peak systolic velocity (MCA-PSV); and PI for veins (PIV) of ductus venosus (DV). The parameters were analyzed in terms of absolute values, z-scores (standard deviations from the mean), or multiples of the median (MoM). The outcome investigated was neonatal death during the hospitalization period after birth.

RESULTS

Of the 93 pregnancies analyzed, there were 25 (26.9%) neonatal deaths. The group that died, when compared to the survival group, presented a significant association with the diagnosis of absent or reversed end-diastolic flow (88% vs. 23.6%, p<0.001), with a higher median of UA PI (2.9 vs. 1.7, p<0.001) and UA PI z-score (10.4 vs. 4.9, p<0.001); higher MCA-PSV MoM (1.4 vs. 1.1, p=0.012); lower BPR (0.4 vs. 0.7, p<0.001); higher PIV-DV (1.2 vs. 0.8, p<0.001) and DV z-score (3.6 vs. 0.6, p<0.001). In the logistic regression, the independent variables predictive of neonatal death were: gestational age at birth (OR=0.45; 95% CI: 0.3 to 0.7; p<0.001) and UA PI z-score (OR=1.14, 95% CI: 1.0 to 1.3, p=0.046).

CONCLUSION

Despite the association verified by the univariate analysis between neonatal death and the parameters of fetal cerebral Doppler velocimetry, the multivariate analysis identified prematurity and degree of insufficiency of placental circulation as independent factors related to neonatal death in pregnancies complicated by placental insufficiency.

Sex specific differences in fetal middle cerebral artery and umbilical venous Doppler

Background

The incidence of several adverse pregnancy outcomes including fetal growth restriction are higher in pregnancies where the fetus is male, leading to suggestions that placental insufficiency is more common in these fetuses. Placental insufficiency associated with fetal growth restriction may be identified by multi-vessel Doppler assessment, but little evidence exists regarding sex specific differences in these Doppler indices or placental function. This study aims to investigate sex specific differences in fetal and placental perfusion and to correlate these changes with intra-partum outcome.

Methods and Findings

This is a prospective cohort study. We measured Doppler indices of 388 term pregnancies immediately prior to the onset of active labour (≤3 cm dilatation). Fetal sex was unknown at the time of the ultrasound assessment. Information from the ultrasound scan was not made available to clinical staff. Case notes and electronic records were reviewed following delivery. We report significantly lower Middle Cerebral artery pulsatility index (1.34 vs. 1.43, p = 0.004), Middle Cerebral artery peak velocity (53.47 cm/s vs. 58.10 cm/s, p = <0.001), and Umbilical venous flow/kg (56 ml/min/kg vs. 61 ml/min/kg, p = 0.02) in male fetuses. These differences however, were not associated with significant differences in intra-partum outcome.

Conclusion

Sex specific differences in feto-placental perfusion indices exist. Whilst the physiological relevance of these is currently unknown, the identification of these differences adds to our knowledge of the physiology of male and female fetuses in utero. A number of disease processes have now been shown to have an association with changes in fetal haemodynamics in-utero, as well as having a sex bias, making further investigation of the sex specific differences present during fetal life important. Whilst the clinical application of these findings is currently limited, the results from this study do provide further insight into the gender specific circulatory differences present in the fetal period.

Two-dimensional and three-dimensional Doppler assessment of fetal growth restriction with different severity and onset

OBJECTIVES

To investigate the role of three-dimensional (3D) power Doppler ultrasonography in the assessment of fetal growth-restriction (FGR) with various degrees of severity and onset, and compare the results with the analysis of two-dimensional (2D) Doppler.

STUDY DESIGN

Vascular indices extracted from 3D Doppler measurements of the placenta were compared with indices of flow-velocity waveforms extracted from 2D Doppler measurements of the major sites of the fetal circulation between FGR (study group) and uncomplicated pregnancies (control group) from 25 to 38 weeks' gestation.

RESULTS

Three-dimensional indices were significantly lower in pregnancies complicated by FGR compared with uncomplicated pregnancies. When measured in placental periphery, vascularization index was 9.4 ± 9.6 in FGR pregnancies compared with 16 ± 14.7, P = 0.04. Flow index was 33.9 ± 6.9 compared with 38.7 ± 4.9, P = 0.03 and the vascularization-flow index was 3.8 ± 4.3 compared with 6.5 ± 6, respectively, P = 0.03. Among the conventional 2D indices, umbilical artery and middle cerebral artery pulsatility indices were not significantly different between the FGR and control groups. Higher rate of maternal or fetal compartment vascular lesions were detected in the FGR group.

CONCLUSIONS

Three-dimensional Doppler was found to be more strongly associated with placental vascular compromise than conventional 2D Doppler, regardless of severity and onset of fetal growth restriction.

Changes in fetal and maternal Doppler parameters observed during acute severe hypertension treatment with hydralazine or labetalol: a randomized controlled trial

We evaluated 16 pregnant women with gestational age between 20 and 32 weeks in acute severe hypertension which were randomly allocated to receive either hydralazine or labetalol. Blood pressure and Doppler ultrasound parameters from maternal uterine and fetal middle cerebral and umbilical arteries were assessed during acute severe hypertension and after treatment. A significant reduction in systolic and diastolic blood pressure was observed in both groups. A significant change in Doppler parameters was observed only in pregnant women who received hydralazine: an increase in uterine arteries resistance index. We concluded that both drugs were highly effective in reducing blood pressure in these women. Despite the observed increase in resistance index of uterine arteries associated with hydralazine, the use of hydralazine and labetalol were not related to any significant changes in fetal Doppler, which is reassuring about the safety of these drugs when treating acute severe hypertension in pregnancy.

Contribution of the myocardial performance index and aortic isthmus blood flow index to predicting mortality in preterm growth-restricted fetuses

OBJECTIVES

To evaluate the predictive value for perinatal death of the myocardial performance index (MPI) and aortic isthmus flow index (IFI), as isolated parameters and in a combined model including currently used Doppler indices, in preterm growth restricted (IUGR) fetuses.

METHODS

Umbilical artery, fetal middle cerebral artery (MCA) and ductus venosus (DV) pulsatility indices (PIs) were recorded, along with IFI and MPI, in a cohort of 97 preterm (delivered at between 24 and 34 weeks) IUGR fetuses. Logistic regression analysis was performed to identify those variables that were independently associated with perinatal mortality, and an algorithm to estimate probability of death was constructed including the best combination of parameters.

RESULTS

With the exception of MCA, all Doppler indices were significantly associated with perinatal death as isolated parameters, but only DV-PI and MPI were found to be independent predictors on multivariate analysis. An algorithm combining DV atrial flow (positive or absent/reversed) and MPI (normal or above 95(th) percentile) had a better predictive accuracy than did any single parameter. The risk for death in IUGR fetuses below 28 weeks' gestation with present atrial flow in the DV and normal MPI was 18%, with either characteristic abnormal it was 70-73%, and with both abnormal it was 97%. The risk for death in IUGR fetuses above 28 weeks with present atrial flow in the DV and normal MPI was 0.1%, with either abnormal it was 6-7%, and with both abnormal it was 45%.

CONCLUSIONS

MPI is an independent predictor of perinatal death in preterm IUGR fetuses with accuracy similar to that of DV flow. A combination of DV flow with MPI may better stratify the estimated probability of death. IFI does not add to the prediction of perinatal death when used in combination with DV flow.

Doppler velocimetry of the uterine, umbilical and fetal middle cerebral arteries in pregnant women undergoing tocolysis with oral nifedipine

OBJECTIVES

To evaluate Doppler velocimetry (resistance index (RI) and peak systolic velocity (PSV)) in the maternal-fetal circulation before and 5 and 24 h after tocolysis with oral nifedipine.

METHODS

This was a prospective, observational, analytic cohort study performed in 47 pregnant women undergoing nifedipine tocolysis, each subject acting as her own control. Doppler assessment of uterine, umbilical and fetal middle cerebral (MCA) arteries was performed before and 5 and 24 h after an initial 20-mg sublingual dose, which was repeated twice at 20-min intervals if contractions failed to diminish. The maintenance dose consisted of 20 mg orally every 6 h for 24 h up to a total of 100-120 mg nifedipine. We analyzed whether there was a time effect and compared values at the different time-points.

RESULTS

The MCA-RI had decreased significantly after 24 h of tocolysis (0 h = 0.85; 5 h = 0.85; 24 h = 0.81; P = 0.001), with no differences in uterine or umbilical arteries or in the MCA to umbilical artery ratio. The MCA-PSV had reduced significantly after 5 h (0 h = 41.5 cm/s; 5 h = 34.7 cm/s; P = 0.001), returning close to baseline levels between 5 and 24 h. The PSV increased significantly between 5 and 24 h in the right uterine artery (5 h = 55.1 cm/s; 24 h = 65.0 cm/s; P = 0.037) and in the umbilical artery (5 h = 28.4 cm/s; 24 h = 33.1 cm/s; P = 0.038).

CONCLUSIONS

Nifedipine tocolysis is associated with a reduction in RI in the MCA but not in the uterine or umbilical arteries, a reduction in PSV in the MCA after 5 h but returning to baseline within 24 h, and an increase in PSV between 5 and 24 h in the umbilical and right uterine arteries.

Predicting fetal asphyxia in intrahepatic cholestasis of pregnancy

PURPOSE

Intrahepatic cholestasis of pregnancy (ICP) is a disease associated with high-perinatal morbidity and mortality rates. It is important to have parameters that aid in predicting fetal outcomes. Certain parameters affecting asphyxia in newborns to mothers with ICP are evaluated in this study.

METHODS

One hundred eighty-seven cholestatic pregnancies were analyzed, retrospectively. Fetal asphyxia was defined as an APGAR score of less than 7 at 5 min postpartum. Predictors of asphyxia in ICP were analyzed by binary multivariate logistic regression analysis.

RESULTS

Thirty-six of the cholestatic pregnancies ended up having an asphyctic newborn at the time of delivery (19.2%). There was a statistically significance difference in the levels of total bile acids (TBA) (42.4 +/- 15.2 vs. 33.8 +/- 12.9 micromol/L, P < 0.01), HDL cholesterol (54.2 +/- 15.9 vs. 61.3 +/- 12.2, P = 0.01), total cholesterol (279.0 +/- 51.4 vs. 257.7 +/- 51.6, P = 0.02), and triacylglycerol (299.4 +/- 94.6 vs. 260.4 +/- 118.7) between the asphytic and nonasphytic group. Binary multivariate logistic regression analysis demonstrated that TBA levels (OR 1.04, 95% CI 1.01-1.08, P = 0.03) and exposure time (OR 1.11, 95% CI 1.05-1.17, P < 0.01) were the most important independent variables predicting fetal asphyxia in ICP.

CONCLUSIONS

In this study, it has been demonstrated that for the evaluation of fetal status, increased TBA levels in the mother and increased exposure time for the fetus to these increased values of TBA within the maternal circulation system help to predict increased risk of asphyxia in newborns to ICP mothers.