Fetal Doppler Studies Research Articles

Effect of Maternal Meal Ingestion on Fetal Renal Artery Resistance

Objective: To examine whether maternal meal ingestion affects the fetal circulation in uncomplicated pregnancies.Methods: A simple crossover blinded study was designed for late uncomplicated singleton pregnancies. After overnight fasting, two different maternal meal states were tested. In one state, pregnant women had a standard 600-kcal breakfast at 8 am (phase A). The other state consisted of maintaining fasting (phase B). Both states were assigned to each woman within 3 days in randomized order. Fetal Doppler studies of the umbilical, middle cerebral, and renal arteries and the descending aorta were performed at 7 am (the fasting state) and at 10 am (the fed state or the continuous fasting state).Results: Twenty women underwent the crossover study. Regardless of the maternal meal state, no significant change was observed in the pulsatility index (PI) of either the umbilical artery (n = 20), the middle cerebral artery (n = 19), or the descending aorta (n = 15). However, the PI of the fetal renal artery decreased significantly after maternal meal ingestion (n = 14) (phase A, 2.36 ± 0.16 versus 2.09 ± 0.33; P = .021). There was no such change in the PI after prolonged fasting (phase B, 2.44 ± 0.32 versus 2.39 ± 0.44; P = .75).Conclusion: Fetal renal artery resistance decreased after maternal meal ingestion in normally grown fetuses during late pregnancy. This decrease in the resistance may be associated with increased fetal urine production after maternal meals.

Lack of effect of antenatal indomethacin on fetal cerebral blood flow

OBJECTIVE: Our purpose was to investigate fetal cerebral blood flow and the incidence of intraventricular hemorrhage in patients undergoing tocolysis with either indomethacin or magnesium sulfate at <30 weeks' gestation. STUDY DESIGN: Consenting patients at <30 weeks' gestation with preterm labor were randomized to receive indomethacin or magnesium sulfate tocolysis. Magnesium sulfate was administered intravenously with an 8 gm loading dose given over the first hour, 4 gm over the second hour, and then a maintenance infusion of 2.5 gm per hour. The infusion was continued for approximately 12 hours after the cessation of uterine contractions. Patients randomized to receive indomethacin were given an initial dose of 50 to 100 mg orally or per rectum, followed by 25 to 50 mg orally every 4 to 6 hours for 24 to 48 hours. Oral tocolytic agents were not used after successful tocolysis. Betamethasone was administered to all patients. Patients underwent fetal cerebral Doppler studies during tocolytic therapy and at least 24 hours after completion of the treatment. RESULTS: Twelve patients were randomized to receive indomethacin and twelve patients were randomized to receive magnesium sulfate. Twenty-one fetuses underwent cerebral Doppler studies in triplicate during and after therapy. The mean gestational age at tocolysis was 27.5 ± 1.9 weeks for the indomethacin group and 26.4 ± 1.6 weeks for the magnesium sulfate group ( p = 0.14). The middle cerebral artery resistance index for fetuses during indomethacin treatment was 0.73 ± 0.09, whereas the resistance index after therapy was 0.75 ± 0.05 ( p = 0.49). The resistance index during magnesium sulfate tocolysis was 0.79 ± 0.04 and after therapy it was 0.76 ± 0.04 ( p = 0.18). There was no significant difference in the resistance index between the groups on or off therapy. In addition, the incidence of intraventricular hemorrhage was similar in both groups. CONCLUSION: These results suggest that indomethacin does not significantly affect fetal cerebral blood flow. If antenatal indomethacin in the preterm fetus increases the risk of intraventricular hemorrhage, it would appear to be by another mechanism. (Am J Obstet Gynecol 1997;176:1166-71.)

Fetal cerebral doppler studies as a predictor of perinatal outcome and subsequent neurologic handicap

To study the use of middle cerebral arterial Doppler findings in a group of high-risk fetuses as a predictor of adverse perinatal outcome, including subsequent neurologic handicap. A group of very high-risk fetuses was recruited over a 2-year period for study. Weekly fetal biometries and Doppler studies of the umbilical artery and middle cerebral arteries were carried out until delivery. Main outcome indices analyzed included birth weight ratio (ratio of observed birth weight to mean birth weight for gestation), days of ventilator requirement, neonatal intracranial hemorrhage or periventricular leukomalacia, necrotizing enterocolitis, and follow-up data on major neurologic handicap and death. Seventy-four patients were recruited. One hundred thirty-four sets of examinations were made and prospective follow-up data were available for up to 2 years. The ratio of the umbilical and middle cerebral arterial resistance index was found to be inversely proportional to the birth weight ratio. Fetuses who had a high prenatal umbilical-cerebral Doppler ratio had significantly lower birth weight ratios than those with normal findings (0.72 versus 0.92; P < .001). The ratio was a more sensitive marker for growth restriction (sensitivity 78%) than conventional fetal biometry and umbilical arterial systolic-diastolic ratio. However, fetuses with high ratios did not have higher incidences of perinatal complications or subsequent neurologic handicap. Prenatal cerebral vasodilation is a sensitive marker for growth restriction and it seems to be a physiologic response to hypoxia. Fetuses with intrauterine cerebral vasodilation do not have increased risk for subsequent gross neurologic damage.

Fetal arterial Doppler studies in twin-twin transfusion syndrome.

This cross-sectional study investigates the circulatory profile of the donor and recipient fetuses in pregnancies with twin-twin transfusion syndrome manifested by acute polyhydramnios during the second trimester of pregnancy. Doppler investigations of the umbilical arteries and of the fetal descending thoracic aortas and middle cerebral arteries were performed in both fetuses of 27 pregnancies with twin-twin transfusion syndrome at 18 to 25 (mean, 21.7) weeks' gestation. Significant differences from normal values were increased umbilical artery pulsatility index and decreased aortic mean velocity in both donor and recipient fetuses, decreased middle cerebral artery pulsatility index in recipients and decreased middle cerebral artery mean velocity in donors. Increased umbilical artery pulsatility index in some donor and recipient fetuses may be the consequence of abnormal placental development and polyhydramnios-related compression, respectively. Doppler findings in the fetal circulation are compatible with hypovolemia in the donor and hypervolemia with congestive heart failure in the recipient.

Antenatal diagnosis of congenital heart disease and fetal arrhythmia by ultrasound: prospective study.

Fetal echocardiographic and Doppler ultrasonographic prospective studies were performed in utero on 299 babies delivered at Hirata Municipal Hospital, Shimane, Japan, from May 1984 to June 1986. Two or three ultrasonographic examinations were performed on each fetus from 20 weeks of gestation to term. Three congenital heart anomalies and 12 fetal arrhythmias were diagnosed antenatally, but 3 heart anomalies (2 small ventricular septal defects and 1 moderate pulmonary stenosis) were not detected in utero. Routine echocardiographic screening appears to be a useful diagnostic tool to detect congenital heart anomalies and fetal arrhythmia antenatally.

Doppler studies in the growth retarded fetus and prediction of neonatal necrotising enterocolitis, haemorrhage, and neonatal morbidity.

In 82 consecutive cases of intrauterine growth retardation managed by established criteria fetal Doppler studies identified 29 fetuses with absence of end diastolic frequencies in the fetal aorta. These same fetuses were significantly more growth retarded (p less than 0.001) and had an earlier gestational age at delivery (p less than 0.001) than those with end diastolic frequencies present. A subgroup of these cases was analysed in more detail to examine the prognostic value of this phenomenon for the neonate. Two groups of neonates of equivalent gestational age and with a birth weight below 2000 g were compared. There were 26 neonates with absent end diastolic frequencies (group 1) and 20 with end diastolic frequencies (group 2) in the fetal aorta. Those in group 1 were more likely to suffer perinatal death (p less than 0.05), necrotising enterocolitis (p less than 0.01), and haemorrhage (p less than 0.05). Only 4 (15%) of the babies in group 1 had an uncomplicated neonatal period compared with 15 (75%) in group 2 (p less than 0.001). The circulatory changes identified in these cases may provide a more sensitive measure of critical fetal compromise than current techniques and thus allow the clinician to deliver the fetus before irreversible tissue damage has occurred.

Resolution and display requirements for ultrasound Doppler/evaluation of the heart in children, infants and the unborn Human fetus

Technical considerations and the instrumentation used for pediatric two-dimensional echocardiography and Doppler examination are reviewed. The configurations of sector scanners, the function of the mechanical versus phased array systems and considerations related to lateral, axial and azimuthal resolution requirements are discussed. The performance and requirements for echocardiographic cardiographic scan converters and the requirements for pediatric display are reviewed. Methods of performing quantitative Doppler echocardiography are discussed because this technique provides new and important types of information for the evaluation of congenital heart disease. Considerations of Doppler velocity, Doppler spatial resolution and Doppler display requirements are presented. Characteristics of ultrasonic imaging devices for use in fetal echocardiography and fetal Doppler study are reviewed, and a brief overview of techniques for the extraction of information about the nature of ultrasound scatterers (that is, tissue signature) is presented. It is the purpose of this technically oriented discussion to present the capabilities, trade-offs and needs for future development relevant to pediatric echocardiography in 1983.