Perinatal outcomes after intrauterine growth restriction and intermittently elevated umbilical artery Doppler

Static and dynamic responses to hyperoxia of normal placenta across gestation with T2*-weighted MRI sequences

OBJECTIVES

T2*-weighted magnetic resonance imaging (MRI) sequences have been identified as non-invasive tools with which to study placental oxygenation in vivo. This study aimed to use these to investigate both static and dynamic responses to hyperoxia of the normal placenta across gestation.

METHODS

We conducted a single-center prospective study including 52 uncomplicated pregnancies. Two T2*-weighted sequences (T2* relaxometry) were performed, one before and one after maternal hyperoxia. The distribution of placental T2* values was modeled by fitting a gamma probability density function (T2* ~ Γ α β ), describing the structure of the histogram using the mean T2* value, the shape parameter (α) and the rate (β). A dynamic acquisition (blood-oxygen-level-dependent (BOLD) MRI) was also performed before and during maternal oxygen supply, until placental oxygen saturation had been achieved. The signal change over time was modeled using a sigmoid function, to determine the intensity of enhancement (ΔBOLD (% with respect to baseline)), a temporal variation coefficient (λ (min-1), controlling the slope of the curve) and the maximum steepness (Vmax (% of placental enhancement/min)).

RESULTS

The histogram analysis of the T2* values in normoxia showed a whole-placenta variation, with a decreasing linear trend in the mean T2* value (Pearson's correlation coefficient (R) = -0.83 (95% CI, -0.9 to -0.71), P < 0.001), along with an increasingly peaked and narrower distribution of T2* values with advancing gestation. After maternal hyperoxia, the mean T2* ratios (mean T2*hyperoxia/mean T2*baseline) were positively correlated with gestational age, while the other histogram parameters remained stable, suggesting a translation of the histogram towards higher values with a similar appearance after maternal hyperoxia. ΔBOLD showed a non-linear increase across gestation. Conversely, λ showed an inverted trend across gestation, with a weaker correlation (R = -0.33 (95% CI, -0.58 to -0.02), P = 0.04, R2 = 0.1). As a combination of ΔBOLD and λ, the changes in Vmax throughout gestation were influenced mainly by the changes in ΔBOLD and showed a positive non-linear correlation with gestational age.

CONCLUSIONS

Our results suggest that the decrease in the T2* placental signal as gestation progresses does not reflect placental dysfunction. The BOLD dynamic signal change is representative of a free-diffusion model of oxygenation and highlights the increasing differences in oxygen saturation between mother and fetus as gestation progresses (ΔBOLD) and in the placental permeability to oxygen (λ). © 2024 International Society of Ultrasound in Obstetrics and Gynecology.

Clinical significance of intermittent absent end-diastolic flow of the umbilical artery in fetal growth restriction

BACKGROUND

Fetal growth restriction can result from a variety of maternal, fetal, and placental conditions. Umbilical artery Doppler assesses the impedance to blood flow along the fetal component of the placental unit. An abnormal umbilical artery waveform reflects the presence of placental insufficiency and can help differentiate a growth-restricted fetus from the constitutionally small, thus guiding further management. The presence of persistently absent end-diastolic flow and reversed end-diastolic flow is an indication for inpatient antenatal surveillance and preterm delivery. There is no consensus on the optimal management of intermittent absent end-diastolic flow owing to a lack of data to support the ideal delivery timing for growth-restricted fetuses with this finding.

OBJECTIVE

This study aimed to estimate the risks of adverse perinatal outcomes among growth-restricted pregnancies with persistently elevated, intermittently absent, and persistently absent end-diastolic flow. Fetal growth restriction is a common condition that is associated with an increased risk of fetal morbidity and mortality. Intermittently absent umbilical artery end-diastolic flow may be identified among pregnancies with fetal growth restriction. The fetal risks associated with persistently absent end-diastolic flow have been described. However, the risks associated with intermittent absent end-diastolic flow are not as well-known.

STUDY DESIGN

We performed a retrospective cohort study including nonanomalous, singleton, growth-restricted pregnancies that received umbilical artery Doppler assessment at our institution from 2009 to 2020. Fetuses were classified into the following 3 categories: elevated umbilical artery Doppler, intermittent absent end-diastolic flow, and persistently absent end-diastolic flow. The Doppler categories were classified by the most severe in the pregnancy. The primary outcome was a composite of neonatal morbidity.

RESULTS

Total 233 fetuses met the criteria. Of which 78 (33.0%) had elevated umbilical artery Doppler waveforms, 37 (16.0%) had intermittent absent end-diastolic flow, and 119 (51.0%) had absent end-diastolic flow. The composite outcome was statistically different between the groups, occurring in 16.9% with elevated umbilical artery Doppler waveforms (13/77), 35.1% (12/39) with intermittent absent end-diastolic flow, and 56.3% (65/127) with absent end-diastolic flow (P<.001). The odds ratio for the composite outcome was significantly increased in absent end-diastolic flow (odds ratio, 6.15; 95% confidence interval, 3.14-12.80) and was not significantly increased for intermittently absent end-diastolic flow (odds ratio, 2.46; 95% confidence interval, 0.98-6.19) when compared with elevated umbilical artery Doppler waveforms. When adjusted for gestational age at delivery and antenatal steroids, no difference was seen in the primary outcome for intermittent absent end-diastolic flow (adjusted odds ratio, 0.73; 95% confidence interval, 0.20-2.68) and absent end-diastolic flow (adjusted odds ratio, 1.44; 95% confidence interval, 0.51-4.07).

CONCLUSION

Among growth-restricted pregnancies, intermittent absent end-diastolic flow is associated with a similar rate of composite neonatal morbidity as persistently elevated Doppler waveforms. In addition, there is no difference in composite neonatal morbidity between the 3 groups when corrected for gestational age at delivery and antenatal steroid administration. These similar outcomes should be considered when creating an antenatal surveillance plan and discussing the potential for outpatient management.

Gestational cholestasis induced intrauterine growth restriction through triggering IRE1α-mediated apoptosis of placental trophoblast cells

Epidemiological and animal experimental studies suggest an association between gestational cholestasis and intrauterine growth restriction (IUGR). Here, we explored the mechanism through which gestational cholestasis induced IUGR. To establish gestational cholestasis model, pregnant mice were subcutaneously injected with 17α-Ethynylestradiol (E2) on gestational day 13 (GD13)-GD17. Some pregnant mice were intraperitoneally injected with 4μ8C on GD13-GD17. The results found that the apoptosis of trophoblast cells was elevated in placentas of mice with gestational cholestasis and in deoxycholic acid (DCA)-treated human trophoblast cell lines and primary mouse trophoblast cells. Correspondingly, the levels of placental cleaved caspase-3 and Bax were increased, while placental Bcl2 level was decreased in mice with gestational cholestasis and in DCA-treated trophoblast cells. Further analysis found that placental IRE1α pathway was activated in mice with gestational cholestasis and in DCA-treated trophoblast cells. Interestingly, 4μ8C, an IRE1α RNase inhibitor, significantly inhibited caspase-3 activity and apoptosis of trophoblast cells in vivo and in vitro. Importantly, 4μ8C rescued gestational cholestasis-induced placental insufficiency and IUGR. Furthermore, a case-control study demonstrated that placental IRE1α and caspase-3 pathways were activated in cholestasis cases. Our results provide evidence that gestational cholestasis induces placental insufficiency and IUGR may be via triggering IRE1α-mediated apoptosis of placental trophoblast cells.

Umbilical cord diameter in the prediction of foetal growth restriction: a cross sectional study

This was a cross sectional study with a prospective design conducted from October 2018 to October 2019. We recruited patients at risk for FGR and normal pregnant women. Each patient had ultrasound examination for the umbilical cord diameter in the 28th, 32nd, 36th, and the 40th week, Foetal growth restriction developed in 10/76 (13.2%) patients in the at risk group. The umbilical cord diameter was significantly lower in the at risk group (1.8 ± 0.2 versus 2.0 ± 0.2 in the control group with a p value of <.001). The umbilical cord diameter was highly predictive for the occurrence of FGR at each antenatal care visit as well as at delivery. We concluded that the umbilical cord diameter was a significant predictor of foetal growth restriction when applied through the antenatal care visits. It is a simple and easy method causing no distress for the patients.IMPACT STATEMENTWhat is already known on this subject? Conflicting results exist regarding the predictive role of the umbilical cord in foetal growth restriction.What do the results of this study add? Foetal umbilical cord diameter was correlated significantly to foetal weight and had a significant predictive role in the prediction of FGR. The cut off values for the umbilical cord diameter in women with FGR were not evaluated before.What are the implications of these findings for clinical practice and/or further research? Comparing the ultrasound findings with histopathologic examination of the umbilical cord and the placentas would be recommended.

Role of umbilicocerebral and cerebroplacental ratios in prediction of perinatal outcome in FGR pregnancies

Purpose

Aim of our study was to compare the prognostic value of the Umbilical-to-Cerebral ratio (UCR) directly to the Cerebroplacental ratio (CPR) in the prediction of poor perinatal outcomes in pregnancies complicated by Fetal Growth Restriction (FGR).

Methods

A retrospective study was carried out on pregnant women with either a small-for-gestational age (SGA) fetus or that were diagnosed with FGR. Doppler measurements of the two subgroups were assessed and the correlation between CPR, UCR and relevant outcome parameters was evaluated by performing linear regression analysis, binary logistic analysis and receiver operator characteristic (ROC) curves. Outcomes of interest were mode of delivery, acidosis, preterm delivery, gestational age at birth as well as birthweight and centiles.

Results

Boxplots and Scatterplots illustrated the different distribution of CPR and UCR leading to deviant correlational relationships with adverse outcome parameters. In almost all parameters examined, UCR showed a higher independent association with preterm delivery (OR: 5.85, CI 2.23–15.34), APGAR score < 7 (OR: 3.52; CI 1.58–7.85) as well as weight under 10th centile (OR: 2.04; CI 0.97–4.28) in binary logistic regression compared to CPR which was only associated with preterm delivery (OR: 0.38; CI 0.22–0.66) and APGAR score < 7 (OR: 0.27; CI 0.06–1.13). When combined with different ultrasound parameters in order to differentiate between SGA and FGR during pregnancy, odds ratios for UCR were highly significant compared to odds ratios for CPR (OR: 0.065, 0.168–0.901; p = 0.027; OR: 0.810, 0.369–1.781; p = 0.601). ROC curves plotted for CPR and UCR showed almost identical moderate prediction performance.

Conclusion

Since UCR is a better discriminator of Doppler values in abnormal range it presents a viable option to Doppler parameters and ratios that are used in clinical practice. UCR and CPR showed equal prognostic accuracy conserning sensitivity and specificity for adverse perinatal outcome, while adding UA PI and GA_scan increased prognostic accuracy regarding negative outcomes.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00404-021-06268-4.

Perinatal outcomes after intrauterine growth restriction and umbilical artery Doppler pulsatility index of less than the fifth percentile

Objective: To analyze perinatal morbidity and stillbirth after intrauterine growth restriction (IUGR) with an umbilical artery Doppler pulsatility index (UA PI) less than the fifth centile.Study design: This retrospective cohort study included nonanomalous singleton, IUGR pregnancies receiving UA PI testing at a tertiary-care prenatal diagnostic center. Women with persistently elevated UA PI, absent or reversed end-diastolic flow on UA PI, or who had only one UA PI result were excluded. Low UA PI was defined as having ≥1 UA PI <5%. Women with low UA PI were matched by gestational age at IUGR diagnosis in a random 1 case: 4 control computer-generated algorithm to those with normal UA PI (≤95% and ≥5%). The primary outcome was composite neonatal morbidity and mortality (stillbirth, mechanical ventilation, sepsis, intraventricular hemorrhage, and necrotizing enterocolitis). Secondary outcomes included 5-minute Apgar, umbilical artery pH, delivery type, and interval from IUGR diagnosis to delivery. We compared outcomes after low UA PI to those after normal UA PI with multivariable logistic regression, adjusting for gestational age at delivery, betamethasone use, infant gender, and maternal factors.Results: Of the 1893 IUGR pregnancies, 25 (1.3%) had low UA PI <5% and were randomly matched via computer algorithm to 100 controls. There were no stillbirths in either group; the odds of composite neonatal morbidity was similar among IUGR pregnancies with UA PI <5% versus normal (adjusted odds ratio 0.89 (95% confidence interval 0.27-2.75)). There was no difference in 5-minute Apgars, umbilical artery pH, rate of cesarean delivery for fetal distress, or interval from IUGR diagnosis to delivery between the two groups.Conclusion: Among IUGR pregnancies, UA PI <5% is uncommon and not associated with improved neonatal outcomes compared to normal UA PI. These findings suggest low UA PI can continue to be managed as normal UA PI.