Arterial and Venous Dopplers in IUGR

Association between Abnormal Antenatal Doppler Characteristics and Gastrointestinal Outcomes in Preterm Infants

Antenatal Doppler disturbances are associated with fetal hypoxia and may induce a brain-sparing vascular redistribution at the expense of splanchnic circulation, possibly predisposing to gut complications. We aimed to compare several gastrointestinal outcomes among very-low-birthweight (VLBW) preterm infants with different antenatal Doppler features. VLBW infants born between 2010-2022 were retrospectively included and stratified into the following clusters based on antenatal Doppler characteristics: normal Doppler (controls); absent or reversed end-diastolic flow in the umbilical artery (UA-AREDF) alone or also in the ductus venosus (UA+DV-AREDF); and abnormal Doppler with or without brain-sparing redistribution. The following outcomes were evaluated: time to reach full enteral feeds (FEF), feeding intolerance (FI), necrotizing enterocolitis (NEC), and spontaneous intestinal perforation (SIP). Overall, 570 infants were included. Infants born following UA+DV-AREDF had significantly higher FI, NEC, and SIP rates and achieved FEF later compared to controls. Increased FI prevalence and a longer time to FEF compared to controls were also observed among UA-AREDF infants and in the presence of brain-sparing redistribution, which also increased NEC rates. Antenatal Doppler abnormalities exacerbate the gastrointestinal risks of preterm infants. Detailed knowledge of Doppler features can aid in identifying those at highest risk of intestinal complications who may benefit from tailored enteral feeding management.

Use of Doppler velocimetry in diagnosis and prognosis of intrauterine growth restriction (IUGR): A Review

Intrauterine growth restriction (IUGR) is a condition which has been difficult to assess at an early stage, resulting in the delivery of children who have poor genetic growth potential. Currently, IUGR classification is based upon the system of ultrasound biometry. Doppler velocimetry allows the measurement of hemodynamic flow of major fetal vessels, comparing the flow indices and patterns of normal and IUGR cases. In this review, the effectiveness of Doppler velocimetry in assessing blood flow in major vessels including the umbilical artery, ductus venosus, and middle cerebral artery was studied for both diagnostic and prognostic screening of IUGR. The umbilical artery is the most frequently studied vessel in Doppler velocimetry due to its accessibility and the strength of its associations with fetal outcomes. Abnormalities in the ductus venosus waveform can be indicative of increased resistance in the right atrium due to placental abnormalities. The middle cerebral artery is the most studied fetal cerebral artery and can detect cerebral blood flow and direction, which is why these three vessels were selected to be examined in this context. A potential mathematical model could be developed to incorporate these Doppler measurements which are indicative of IUGR, in order to reduce perinatal mortality. The purpose of the proposed algorithm is to integrate Doppler velocimetry with biophysical profiling in order to determine the optimal timing of delivery, thus reducing the risks of adverse perinatal outcomes.

Ductus venosus versus cerebral transverse sinus Doppler velocimetry for predicting acidemia at birth in pregnancies complicated by placental insufficiency

OBJECTIVES

The objectives of this study is to compare ductus venosus (DV) and cerebral transverse sinus (CTS) Doppler velocimetry for predicting acidemia at birth in pregnancies complicated by placental insufficiency.

METHODS

A prospective cross-sectional study involving 69 cases. Doppler assessment of the DV and CTS was carried out in the last 24 hours prior to delivery. The sensitivity, specificity, positive and negative predictive values, and the accuracy and false-positive and false-negative rates were calculated for those parameters considered to be good predictors of acidemia. The McNemar test was used to compare the various parameters.

RESULTS

The DV pulsatility index(PI), S/A, and (S - A)/S ratios as well as the CTS PI and the (S - A)/S ratio were good predictors of acidemia. The comparison between DV and CTS showed that for pulsatility index for veins, the sensitivity was 52.4% versus 66.7%, p = 0.508; the specificity was 81.2% versus 77.1%, p = 0.774; and the accuracy was 72.5% versus 73.9%, p = 1.00. For the (S - A)/S ratio the sensitivity was 52.4% versus 52.4%, p = 1.00; the specificity was 85.4% versus 79.2%, p = 0.508; and the accuracy was 75.4% versus 71%, p = 0.647.

CONCLUSIONS

In pregnancies with placental insufficiency, the PI and the (S - A)/S ratio of both DV and CTS were equally effective in predicting acidemia at birth.

Suppression of trophoblast uterine spiral artery remodeling by estrogen during baboon pregnancy: impact on uterine and fetal blood flow dynamics

The present study was conducted to determine the impact of suppressing trophoblast remodeling of the uterine spiral arteries by prematurely elevating estrogen levels in the first trimester of baboon pregnancy on uterine and umbilical blood flow dynamics. Uteroplacental blood flow was assessed by Doppler ultrasonography after acute administration of saline (basal state) and serotonin on days 60, 100, and 160 of gestation (term: 184 days) to baboons in which uterine spiral artery remodeling had been suppressed by the administration of estradiol on days 25-59 of gestation. Maternal blood pressure in the basal state was increased (P < 0.01), and uterine artery diastolic notching and the umbilical artery pulsatility index and systolic-to-diastolic ratio, reflecting downstream flow impedance, were increased (P < 0.01) after serotonin administration on day 160, but not earlier, in baboons treated with estradiol in early gestation. These changes in uteroplacental flow dynamics in serotonin-infused, estradiol-treated animals were accompanied by a decrease (P < 0.05) in uterine and umbilical artery volume flow and fetal bradycardia. The results of this study show that suppression of uterine artery remodeling by advancing the rise in estrogen from the second trimester to the first trimester disrupted uteroplacental blood flow dynamics and fetal homeostasis after vasochallenge late in primate pregnancy.

Multivascular Doppler surveillance in high risk pregnancies

OBJECTIVES

Analysis of fetal arterial and venous Doppler predictability for adverse perinatal outcome.

METHODS

Blood flow in the uterine, umbilical and middle cerebral arteries, umbilical vein, ductus venosus and Galen vein were examined with in 72 h of delivery in 88 high-risk pregnancies. The managing clinicians were only informed about the results of the umbilical artery Doppler. The Doppler results were correlated to adverse perinatal outcome.

RESULTS

Doppler abnormalities were seen in both preterm and term pregnancies. Umbilical venous pulsations (n = 13) were strongly correlated to Apgar score <7 at 5 min, abnormal blood gases, need for ventilation assistance and operative delivery for fetal distress. Twenty-four fetuses had brain sparing in the middle cerebral artery, and forty-five had abnormal umbilical artery Doppler. These were correlated to admission in the neonatal intensive care unit, operative delivery and prematurity. Brain sparing in middle cerebral artery was also correlated to ventilation disturbances in the newborns. Abnormal ductus venosus blood velocity was only seen in 9 cases and not related to adverse outcome. Galen vein pulsations (n = 26) seem to appear earlier than pulsations in the umbilical vein and were not related to adverse outcome. conclusion: Umbilical vein pulsations were better correlated to adverse perinatal outcome than were other Doppler findings including ductus venosus.

Prediction of acidemia at birth by Doppler assessment of fetal cerebral transverse sinus in pregnancies with placental insufficiency

OBJECTIVES

To evaluate the prediction of acidemia at birth using cerebral transverse sinus (CTS) Doppler velocimetry and to determine the best parameter and cut-off values for its prediction in pregnancies complicated with placental insufficiency.

METHODS

This was a prospective cross-sectional study involving 69 pregnant women (26-40 weeks' gestation) with placental insufficiency managed in two Brazilian hospitals. Doppler assessment of the CTS was carried out in the last 24 h before delivery, and the peak ventricular systolic (S-wave) and diastolic (D-wave) velocities as well as the atrial systolic velocity (A-wave) were recorded and the pulsatility index for veins (PIV) was calculated. At birth, arterial and venous umbilical cord blood samples were collected to determine acid-base and pH status. A receiver-operating characteristics (ROC) curve was constructed for each Doppler parameter with birth acidemia as the dependent variable. Sensitivity, specificity, positive and negative predictive values, accuracy and false-positive and false-negative rates were calculated for the parameters considered to be good predictors of acidemia.

RESULTS

The S, D and A peak velocities and the S/A ratio were not good predictors of acidemia at birth. The PIV and the (S - A)/S ratio were good predictors of acidemia (area under the ROC curve = 0.698 (P = 0.009) and 0.654 (P = 0.009), respectively). The cut-off values were PIV = 0.855 and (S - A)/S = 0.703).

CONCLUSIONS

The PIV and the (S - A)/S ratio of the CTS were good predictors of acidemia at birth in this high-risk population with placental insufficiency.

Reduced maternal serum concentrations of angiopoietin-2 in the first trimester precede intrauterine growth restriction associated with placental insufficiency

The aim of this study was to investigate whether maternal serum levels of angiopoietin-2 (Ang-2) and pregnancy-associated plasma protein A (PAPP-A) are associated with subsequent intrauterine growth restriction (IUGR). Ang-2 was measured in 29 nonpregnant and 44 pregnant women at 10-13 weeks of gestation. The median concentration of Ang-2 was 26.61 ng/ml in normal pregnant women compared with 1.71 ng/ml in nonpregnant controls (P < 0.01). Women who subsequently developed severe IUGR had lower levels of Ang-2 compared with normal pregnant controls (P < 0.01). PAPP-A levels were similar in all pregnant groups. These findings suggest that Ang-2 should be evaluated for its ability to predict pregnancies that later are affected by IUGR.

Correlation of fetal DNA levels in maternal plasma with Doppler status in pathological pregnancies

OBJECTIVES

To evaluate whether intrauterine growth restriction (IUGR) as seen in preeclampsia is associated with high levels of fetal DNA in maternal circulation, and whether fetal DNA is related to altered uterine and/or umbilical artery Doppler velocimetry.

METHODS

Fetal DNA quantification was performed by real-time PCR on SRY sequences in 64 male-bearing pregnant women with IUGR and/or preeclampsia and 89 controls.

RESULTS

Fetal DNA content was significantly elevated in IUGR pregnancies similar to preeclampsia and correlated with altered umbilical Doppler velocimetry, while no correlation was found with uterine Doppler status.

CONCLUSION

Increased fetal DNA levels in maternal plasma may be a sign of placental or fetal pathology even in the presence of normal uterine Doppler velocimetry, allowing a more precise diagnostic evaluation. The finding that elevated fetal DNA in IUGR pregnancies correlates with abnormal umbilical Doppler velocimetry suggests that fetal DNA release is associated more with fetal chronic hypoxia than with fetal size.

Venous-arterial Doppler ratios in the prediction of acidemia at birth in pregnancies with placental insufficiency

OBJECTIVES

Investigate the prediction of birth acidemia in pregnancies with placental insufficiency using two newly created venous-arterial Doppler ratios: pulsatility index (PI) of the ductus venosus (DV) over PI of the middle cerebral artery (MCA) and PI of the DV over PI of the umbilical artery and establish cut-off values for this prediction.

METHODS

This was a prospective cross-sectional study involving 47 patients with placental insufficiency managed in two Brazilian hospitals. All pregnancies were singleton, over 26 weeks of age and without structural or chromosome anomalies. A ROC curve was calculated for the venous-arterial ratios (independent variable) and acidemia (dependent variable).

RESULTS

The DV/AU PI ratio was not a good predictor of acidemia at birth. The DV/MCA PI ratio was related to fetal acidemia (area under the ROC curve 0.785, p = 0.004). The cut-off value was 0.582, sensibility 66.7%, specificity 77.1% and accuracy 74.5%.

CONCLUSIONS

The DV/MCA PI ratio is adequate for the diagnosis of acidemia at birth in pregnancies with placental insufficiency. The cut-off value was 0.582.

Comparison between color Doppler cineloop- and conventional spectral Doppler-derived maximum velocity and flow in the umbilical vein

OBJECTIVE

To compare the umbilical venous flow velocity derived from color Doppler cineloop recordings with that derived from conventional spectral Doppler in normal pregnancies.

METHOD

In 18 uncomplicated pregnancies between 19 and 39 weeks' gestation, color Doppler was used to find the maximum velocity in the cross-sectional vessel area of a free-floating loop of the umbilical vein. The maximum velocity was determined using the software tool HDI_Lab (Philips Medical Systems) after tracing the vessel area of interest. Conventional spectral Doppler was then used to determine the maximum velocity with the High-Q machine option. The cross-sectional area of the umbilical vein was determined using B-mode imaging and was subsequently used to determine the umbilical volume flow from both Doppler methods. Assuming a parabolic flow profile in the umbilical vein, the mean velocity is equal to half the maximum velocity. The fetal weight was estimated from fetal biometry using the four-parameter Hadlock formula.

RESULTS

Maximum velocity was significantly (P = 0.003) higher with color Doppler cineloop (14.3 +/- 2.5 cm/s) compared with spectral Doppler (12.7 +/- 3.2 cm/s). Therefore, using the same cross-sectional area for both methods, the umbilical blood flow was significantly higher (P = 0.001) with color Doppler cineloop (127.9 +/- 59.0 mL/min) than it was with spectral Doppler (112.8 +/- 54.1 mL/min). The umbilical blood flow expressed as volume flow per kg fetal weight was significantly (P = 0.01) higher with color Doppler cineloop (126.0 +/- 57.0 mL/min/kg) than it was with spectral Doppler (115.0 +/- 53.0 mL/min/kg).

CONCLUSIONS

Umbilical venous flow velocity derived from color Doppler cineloops is approximately 10% higher than that derived from spectral Doppler-derived velocity. The reduced angle dependence of the color Doppler cineloop technique and the large sampling area of the cross-sectional vessel should allow better determination of the correct maximum velocity in the umbilical vein.

Pulmonary balloon valvuloplasty in a fetus with critical pulmonary stenosis/atresia with intact ventricular septum and heart failure

Outcome of fetuses with critical pulmonary stenosis (critical PS) or atresia of the pulmonary valve (PA) with intact ventricular septum (IVS) is closely related with right ventricle hypoplasia and its consequent hemodynamics. Fetal echocardiography not only allows early detection of this condition but also monitors its normally unfavorable evolution. These cases may benefit from intrauterine intervention relieving outflow tract obstruction in order to achieve a biventricular circulation. Successful valvuloplasty of the pulmonary valve was performed in a fetus with critical PS-IVS and heart failure at 25 weeks. After the procedure there was a significant improvement in fetal hemodynamics. Follow-up scans at 34 weeks detected a significant restenosis with signs of circulatory failure leading to premature delivery of the baby. An immediate postnatal valvuloplasty successfully completed the ultimate objective of biventricular repair. Fetal pulmonary valvuloplasty is feasible and may change the natural history of the disease in fetuses with critical PS-IVS.

Embryonic and Neonatal Phenotyping of Genetically Engineered Mice

Considerable progress has been made in adapting existing and developing new technologies to enable increasingly detailed phenotypic information to be obtained in embryonic and newborn mice. Sophisticated methods for imaging mouse embryos and newborns are available and include ultrasound and magnetic resonance imaging (MRI) for in vivo imaging, and MRI, vascular corrosion casts, micro-computed tomography, and optical projection tomography (OPT) for postmortem imaging. In addition, Doppler and M-mode ultrasound are useful noninvasive tools to monitor cardiac and vascular hemodynamics in vivo in embryos and newborns. The developmental stage of the animals being phenotyped is an important consideration when selecting the appropriate technique for anesthesia or euthanasia and for labeling animals in longitudinal studies. Study design also needs to control for possible differences between inter- and intralitter variability, and for possible long-term developmental effects caused by anesthesia and/or procedures. Noninvasive or minimally invasive intravenous or intracardiac injections or blood sampling, and arterial pressure and electrocardiography (ECG) measurements are feasible in newborns. Whereas microinjection techniques are available for embryos as young as 6.5 days of gestation, further advances are required to enable minimally invasive fluid or tissue samples, or blood pressure or ECG measurements, to be obtained from mouse embryos in utero. The growing repertoire of techniques available for phenotyping mouse embryos and newborns promises to accelerate knowledge gained from studies using genetically engineered mice to understand molecular regulation of morphogenesis and the etiology of congenital diseases.

Ductus venosus Doppler velocimetry in the prediction of acidemia at birth: which is the best parameter?

OBJECTIVES

To evaluate the prediction of acidemia at birth using ductus venosus Doppler velocimetry and to determine the best parameter and cut-off values for this prediction in pregnancies complicated with placental insufficiency.

METHODS

Prospective cross-sectional study. Forty-seven patients with placental insufficiency managed in two Brazilian hospitals were submitted to ductus venosus Doppler velocimetry in the last 24 h before delivery. All pregnancies were singleton, at least 26 weeks of age and without structural or chromosomal anomalies. A ROC curve was calculated for each ductus venosus parameter (independent variable) and acidemia (dependent variable). A cut-off value was established. The McNemar test was used to compare the various parameters.

RESULTS

The ductus venosus S, D and A peak velocities were not good predictors of acidemia at birth. Pulsatility Index for Veins (PIV) was a good predictor of acidemia (ROC curve area 0.79, p = 0.003), as well as S/A and (S - A)/S ratios (ROC curve area 0.818, p = 0.001). The cut-off values were PIV = 0.76, S/A = 2.67 and (S - A)/S = 0.63.

CONCLUSIONS

In this high-risk population, angle-independent ductus venosus Doppler indexes were good predictors of birth acidemia. The S/A and (S - A)/S ratios and the ductus venosus PIV were statistically equivalent in this prediction.