Patterns of Brain Sparing in a Fetal Growth Restriction Cohort

Objective: Our objective was to compare differences in Doppler blood flow in four fetal intracranial blood vessels in fetuses with late-onset fetal growth restriction (FGR) vs. those with small for gestational age (SGA). Methods: Fetuses with estimated fetal weight (EFW) <10th percentile were divided into SGA (n = 30) and FGR (n = 51) via Delphi criteria and had Doppler waveforms obtained from the middle cerebral artery (MCA), anterior cerebral artery (ACA), posterior cerebral artery (PCA), and vertebral artery (VA). A pulsatility index (PI) <5th centile was considered “abnormal”. Outcomes included birth metrics and neonatal intensive care unit (NICU) admission. Results: There were more abnormal cerebral vessel PIs in the FGR group versus the SGA group (36 vs. 4; p = 0.055). In FGR, ACA + MCA vessel abnormalities outnumbered PCA + VA abnormalities. All 8 fetuses with abnormal VA PIs had at least one other abnormal vessel. Fetuses with abnormal VA PIs had lower BW (1712 vs. 2500 g; p < 0.0001), delivered earlier (35.22 vs. 37.89 wks; p = 0.0052), and had more admissions to the NICU (71.43% vs. 24.44%; p = 0.023). Conclusions: There were more anterior vessels showing vasodilation than posterior vessels, but when the VA was abnormal, the fetuses were more severely affected clinically than those showing normal VA PIs.

Reference values for pulsatility index of fetal anterior and posterior cerebral arteries in prolonged pregnancy

OBJECTIVE

To establish consistent normal reference values for fetal anterior cerebral artery (ACA) and posterior cerebral artery (PCA) pulsatility index (PI) in prolonged pregnancy.

METHODS

This prospective cross-sectional observational study included singleton normal prolonged pregnancies into two study groups according to the gestational age: from 40 + 0 to 40 + 6 and from 41 + 0 to 41 + 6 weeks. The PI was assessed in both anatomical segments of ACA (ACA-S1 and ACA-S2) and of PCA (PCA-S1 and PCA-S2) with color Doppler imaging and pulsed Doppler examination, and reference centiles charts were generated. PI values from the two investigated segments of each vessel were also compared.

RESULTS

Data were obtained in 771 patients: n = 448 in the 40 + 0 and 40 + 6 weeks group, and n = 323 in the 41 + 0 and 41 + 6 weeks group. A moderate decrease in PI was observed as pregnancy progressed. No differences in PI values were found between the two anatomical segments of ACA and PCA.

CONCLUSION

This study provides Doppler reference values for the fetal ACA and PCA PI. It also shows that Doppler examination could be performed indifferently in one of the two anatomical segments of these arteries.

Doppler evaluation of the posterior cerebral artery in fetuses with transposition of great arteries

Objective To observe Doppler ultrasound changes in the two segments of the posterior cerebral artery (PCA) in fetuses with transposition of the great arteries (TGA). Methods The peak systolic velocity (PSV), end-diastolic velocity (EDV), pulsatility index (PI), and velocity-time integral (VTI) of the two segments of PCA (the first segment: PCAS1, the second segment: PCAS2) and of the middle cerebral artery (MCA) were compared in TGA fetuses and normal fetuses. The abnormality rate between the PCAS1-PI and MCA-PI was compared in TGA fetuses. Results The PCAS1-PI and MCA-PI were smaller in the TGA fetuses than in the controls (all P < 0.05), but the PCAS2-PI was unchanged (P > 0.05). The MCA-VTI, PCAS1-VTI, and PCAS2-VTI were larger in the TGA fetuses (all P < 0.05). In the TGA fetuses, the abnormality rate of the PCAS1-PI was significantly higher than that of the MCA-PI (P < 0.05). Conclusion In fetuses with TGA, there were hemodynamic differences between the two segments of the posterior cerebral arteries. Moreover, PCAS1 exhibited signs of vasodilatation more obviously than did the MCA in fetuses with TGA.

Feto-placental Dopplers are not altered in women with obstructive sleep apnoea symptoms

BACKGROUND

Snoring, gasping or choking during sleep are common symptoms of sleep-disordered breathing and are associated with multiple adverse maternal and obstetric outcomes. The mechanisms responsible remain unknown; however, placental dysfunction is suspected.

AIMS

The aim of this study was to investigate feto-placental and fetal cardiac function in women with pregnancies complicated by obstructive sleep apnoea symptoms.

MATERIALS AND METHODS

This was a prospective observational cohort study at a large tertiary obstetric hospital in Australia. Women were asked to complete a questionnaire relating to the presence and severity of obstructive sleep apnoea symptoms. They also underwent an ultrasound scan where Doppler indices of various feto-placental vessels and fetal cardiac function were measured. Regional cerebral perfusion was also assessed.

RESULTS

A total of 255 women were included in the final analysis. Of these, 36.1% (92/255) of women reported no obstructive sleep apnoea symptoms; 63.9% (163/255) reported they experienced some form of obstructive sleep apnoea symptoms that included any frequency of snoring or choking/gasping, while 42.0% (107/255) complained of severe obstructive sleep apnoea symptoms (snoring ≥ 3 times a week or choking/gasping). There were no significant differences in feto-placental Dopplers or fetal cardiac function parameters in women with obstructive sleep apnoea symptoms. There were also no differences in regional cerebral blood flow between groups, or any correlation with severity of symptoms.

CONCLUSIONS

Our data challenge the current perspective that adverse perinatal outcomes in women with obstructive sleep apnoea symptoms are related primarily to placental dysfunction and fetal compromise.

Fetal acute cerebral vasoreactivity to maternal hyperoxia in low-risk pregnancies: a cross-sectional study

OBJECTIVE

To establish whether fetal cerebral vasoreactivity (CVR_O2 ), following maternal hyperoxia, is predicted by fetal cerebral and uteroplacental Doppler pulsatility indices (PI) at baseline, fetal pulmonary vasoreactivity to oxygen (PVR_O2 ), gestational age (GA), or sex.

METHODS

Pulsatility index of middle (MCA), anterior (ACA), posterior cerebral (PCA), umbilical (UA), uterine (UtA), and branch of the pulmonary arteries (PA) were obtained, by ultrasound, before (baseline), during (hyperoxia) and after 15 minutes of maternal administration of 8 L/min of 100% oxygen, through a non-rebreathing face mask, in normal singleton pregnancies within 20 to 38 weeks' gestation. CVR_O2 was defined as changes greater than zero in z score of PI of the cerebral arteries from baseline to hyperoxia. Logistic modeling was applied to identify CVR_O2 predictors.

RESULTS

A total of 97 pregnancies were eligible. In the overall population, median z scores of PI of MCA, ACA, and PCA did not differ between study phases. Based on the logistic model, baseline z scores for cerebral PI and GA were the best predictors of CVR_O2 .

CONCLUSIONS

In low-risk pregnancies, fetal CVR_O2 to hyperoxia does not occur uniformly but depends on cerebral PI and GA at baseline. These findings may provide useful reference points when oxygen is administered in high-risk pregnancies.

Fetal brain hemodynamics in pregnancies at term: correlation with gestational age, birthweight and clinical outcome

INTRODUCTION

The primary aim of this study was to ascertain the strength of association between cerebral blood flow assessed in anterior (ACA), middle (MCA), and posterior (PCA) cerebral arteries and the following clinical outcomes: small for gestational age (SGA), induction of labor (IOL) for oligohydramnios and caesarean section (CS) for nonreassuring fetal status (NRFS) during labor.

MATERIAL AND METHODS

Retrospective analysis of prospectively collected data on consecutive singleton pregnancies from 40 0/7 to 41 6/7 week of gestation. UA, ACA, MCA, PCA pulsatility index (PI) were measured from 40 weeks of gestations. Furthermore, the ratios between cerebral blood flow and UA (CPR, ACA/UA and PCA/UA) were calculated and correlated with the observed outcomes.

RESULTS

Two hundred twenty-four singleton pregnancies were included in the study. Mean PI of either ACA (p = .04), MCA (p = .008), and PCA (p = .003) were lower in the SGA compared to non-SGA group; furthermore, mean PCA PI was significantly lower than MCA PI (p = .04). Furthermore, CPR (p = .016), ACA/UA (p = .02), and PCA/UA (p = .003) were significantly lower in the SGA group compared to controls. UA, ACA, MCA, and PCA PI were higher in women undergoing IOL for oligohydramnios compared to controls. Logistic regression analysis showed that CPR and PCA/UA ratio were independently associated with SGA. SGA, ACA PI, and ACA/UA were independently associated with CS for NRFS. Finally, birthweight centile, were independently associated with IOL oligohydramnios. Despite this, the predictive accuracy of Doppler in detecting any of the explored outcome was only poor to moderate.

CONCLUSION

Redistribution of cerebral blood flow at term is significantly associated with SGA, IOL for oligohydramnios and CS for NRFS in labor. However, the predictive accuracy of Doppler at term is only poor to moderate, thus advising against its use in clinical practice as a standalone screening test for adverse perinatal outcome in pregnancies at term. Key Message Redistribution of cerebral blood flow at term is significantly associated with SGA, IOL for oligohydramnios and CS for NRFS in labor.

Reproducibility of the fetal cerebral vessels assessment in full and late term pregnancies

Objective: Data concerning feasibility of the fetal cerebral Doppler examination in full term and late term pregnancy is lacking. Our purpose was to perform an evaluation of these arteries with power Doppler ultrasound, calculating the percentage of identification and measurement and the intraobserver reproducibility.Methods: This was a cross sectional study evaluating a population of 578 normally grown fetuses divided according to the week of examination. The first group included fetuses examined at week 40 (N = 323) and the second fetuses examined at week 41 (N = 255). The three major branches of the internal carotid artery (anterior, middle and posterior cerebral arteries, ACA, middle cerebral artery (MCA), posterior cerebral arteries (PCA)) and their anastomosis (A1, A2, P1, P2) were examined with power Doppler ultrasonography by three independent ultrasonographers. The proportion of vessel identified and measured was calculated and the reproducibility among the three operators was investigated.Results: The major arteries at the circle of Willis were fully identified/measured in 65/56 and 62/48% of fetuses at 40 and 41 weeks. The MCA obtained the higher percentage of identification and measurement at both periods (> 80 and >70%). The entire set of anastomosis were less frequently identified/measured at both periods (50/< 50% of cases), especially in the A2 segment. The best agreement was obtained in the MCA and the worst in the PCA-P1 segment.Conclusions: At 40 and 41 weeks, the fetal cerebral vessels, especially the MCA, are suitable for power Doppler evaluation, providing an interesting tool to evaluate fetal hemodynamics in full and late term pregnancy.

Different vasodilatation characteristics among the main cerebral arteries in fetuses with congenital heart defects

To observe Doppler changes in the three main cerebral arteries in fetuses with congenital heart defects (CHDs). The pulsatility index (PI) values of the anterior cerebral artery (ACA), middle cerebral artery (MCA), and posterior cerebral artery (PCA) were prospectively compared in 78 CHD fetuses and 78 normal control fetuses. Correlations between the cerebral artery PIs and the neurodevelopment scores (psychomotor development index [PDI] and mental development index [MDI]) were assessed. The MCA-PI was decreased significantly in fetuses with hypoplastic left heart syndrome (HLHS). The ACA-PI was reduced significantly in fetuses with HLHS, fetuses with left-sided obstructive lesions (LSOLs) and fetuses with transposition of the great arteries. The PCA-PI was significantly smaller in fetuses with HLHS and fetuses with LSOLs. More fetuses presented signs of cerebral vasodilatation of the ACA than the MCA for certain types of CHD (P < 0.05). The ACA-PI was positively correlated with the PDI and MDI scores in fetuses with CHDs (r² = 0.26, 0.20, P < 0.01). The MCA-PI was only positively correlated with the PDI scores (r² = 0.15, P < 0.01). The ACA exhibited signs of vasodilatation more frequently and severely than the MCA. The ACA-PI appears to be more sensitive for predicting abnormal neurodevelopmental outcomes than the MCA-PI.