Umbilical Artery Blood Velocity Waveforms Research Articles

Umbilical Artery N-Terminal Peptide of Proatrial Natriuretic Peptide in Hypertensive Pregnancies and Fetal Acidemia During Labor

In Brief Objective To assess the activity of the human fetal atrial natriuretic peptide system in hypertensive pregnancies with and without signs of increased fetal systemic venous pressure and in pregnancies complicated by fetal acidemia during labor. Methods Umbilical artery plasma N-terminal peptide of proatrial natriuretic peptide concentrations were measured in neonates by radioimmunoassay. The control group consisted of 50 neonates with uncomplicated gestation and labor. In group 1, there were 22 newborns of hypertensive pregnancies. Doppler ultrasonography showed abnormal umbilical artery blood velocity waveform in five cases and normal nonpulsatile umbilical vein blood velocity profile in every case. Group 2 consisted of five newborns of pregnancies complicated by maternal hypertensive disorder. Atrial pulsations in the umbilical vein and retrograde diastolic blood velocity pattern in the umbilical artery were detected in every case. Group 3 was composed of 27 newborns of uncomplicated pregnancies with fetal acidemia (pH 7.10 or less) during labor. Results In groups 1–3, N-terminal peptide of proatrial natriuretic peptide concentrations were higher (P < .001) than in the control group. In group 1, neonates with abnormal umbilical artery blood velocity pattern had higher N-terminal peptide of proatrial natriuretic peptide concentrations than neonates with normal umbilical artery Doppler findings (P < .006). N-terminal peptide of proatrial natriuretic peptide concentrations were higher in group 2 (P < .002) than in groups 1 and 3. Conclusion Maternal hypertensive disorder and fetal acidemia during labor stimulate fetal atrial natriuretic peptide production, which was greatest in fetuses with severe placental insufficiency and signs of congestive heart failure. Maternal hypertension and fetal acidemia during labor stimulate human fetal atrial natriuretic peptide production, which is highest in fetuses with severe placental insufficiency and congestive heart failure.

Umbilical artery N-terminal peptide of proatrial natriuretic peptide in hypertensive pregnancies and fetal acidemia during labor

Objective: To assess the activity of the human fetal atrial natriuretic peptide system in hypertensive pregnancies with and without signs of increased fetal systemic venous pressure and in pregnancies complicated by fetal acidemia during labor. Methods: Umbilical artery plasma N-terminal peptide of proatrial natriuretic peptide concentrations were measured in neonates by radioimmunoassay. The control group consisted of 50 neonates with uncomplicated gestation and labor. In group 1, there were 22 newborns of hypertensive pregnancies. Doppler ultrasonography showed abnormal umbilical artery blood velocity waveform in five cases and normal nonpulsatile umbilical vein blood velocity profile in every case. Group 2 consisted of five newborns of pregnancies complicated by maternal hypertensive disorder. Atrial pulsations in the umbilical vein and retrograde diastolic blood velocity pattern in the umbilical artery were detected in every case. Group 3 was composed of 27 newborns of uncomplicated pregnancies with fetal acidemia (pH 7.10 or less) during labor. Results: In groups 1–3, N-terminal peptide of proatrial natriuretic peptide concentrations were higher ( P < .001) than in the control group. In group 1, neonates with abnormal umbilical artery blood velocity pattern had higher N-terminal peptide of proatrial natriuretic peptide concentrations than neonates with normal umbilical artery Doppler findings ( P < .006). N-terminal peptide of proatrial natriuretic peptide concentrations were higher in group 2 ( P < .002) than in groups 1 and 3. Conclusion: Maternal hypertensive disorder and fetal acidemia during labor stimulate fetal atrial natriuretic peptide production, which was greatest in fetuses with severe placental insufficiency and signs of congestive heart failure.

Association of severe placental insufficiency and systemic venous pressure rise in the fetus with increased neonatal cardiac troponin T levels

Objective: The aim of this study was to test the hypothesis that severe placental insufficiency and a rise in fetal systemic venous pressure are associated with fetal myocardial cell damage, which in turn leads to increased neonatal troponin T levels. Study Design: Sixty-six neonates born after uncomplicated pregnancy and delivery were included in the control group. Study groups 1 and 2 consisted of 32 and 5 neonates, respectively, born to women with hypertensive disorder. In study group 1 the fetal intra-abdominal portion of the umbilical vein showed normal nonpulsatile blood flow pattern in every case. In study group 2 all the fetuses had atrial pulsations in the intraabdominal umbilical vein. After delivery blood samples were collected from the umbilical arteries, and cardiac troponin T concentrations were measured with commercially available enzyme-linked immunosorbent assay kits. A clinically significant troponin T level was set at ≥0.10 ng/mL. Results: In study group 1 the maternal main uterine arterial blood flow pattern was normal in 30 cases and abnormal in 2 cases. Umbilical artery blood velocity waveforms were normal in 26 fetuses, 4 fetuses had a decreased diastolic blood flow, 1 fetus had an absent diastolic blood flow pattern, and 1 fetus had a retrograde diastolic blood flow pattern. In study group 2 maternal uterine arterial Doppler findings were abnormal in every case, and all the fetuses had retrograde diastolic blood flow pattern in the umbilical artery. Neonatal troponin T levels were <0.10 ng/mL in the control group (0-0.14 ng/mL) and in study group 1 (0-0.16 ng/mL), except for 1 case in each group. Every neonate in study group 2 had a troponin T level >0.10 ng/mL, with the range from 0.11 to 0.35 ng/mL. In study group 2 troponin T concentrations were significantly higher (P <.0001) than in either the control group or study group 1. Conclusion: Neonatal troponin T levels are not clinically significantly increased in normal pregnancies and in pregnancies complicated by maternal hypertensive disorder but with normal fetal umbilical venous return. Neonatal troponin T concentrations are significantly increased in the presence of abnormal umbilical venous return, which indicates myocardial cell damage. (Am J Obstet Gynecol 2000;183:726-31.)

The effect of intravascular transfusion for severely anemic fetuses on umbilical artery Doppler flow velocity waveforms.

To evaluate whether the doppler flow velocity waveforms reflect the fetal hematocrit and to assess the changes of the umbilical artery doppler indices before and after the puncture of the umbilical cord. In this prospective-study, Pulsed-Doppler examinations of blood flow velocities in the umbilical artery were carried out before and after 22 diagnostic cordocentesis and 14 fetal blood transfusions into the umbilical vein. There were decreases in the systolic/diastolic ratio (p < 0.001), the pulsatility index (PI)(p < 0.001), and the resistance index (RI)(p < 0.003) after cordocentesis but not after fetal blood transfusion. There were no correlations between the initial hematocrit and the umbilical artery doppler indices in both fetal blood transfusion group and fetal blood sampling group. There was no correlation between the increase in hematocrit and changes in umbilical artery blood-velocity waveform indices following fetal blood transfusion. The umbilical artery doppler flow-velocity indices did not predict the fetal hematocrit. These findings suggest that acute changes in blood viscosity following intravascular transfusion are not associated with an increase in resistance to flow as assessed by doppler velocimetry. Umbilical blood sampling per se may be associated with a humorally mediated reduction in placental vascular resistance to flow.

Correlation between umbilical arterial flow and placental morphology.

Umbilical artery blood velocity waveforms were compared with the morphological aspects of the vascular bed of 30 placentas using quantitative methods. An abnormal pulsatility index was found to be highly correlated with a lower number of arteries in the tertiary stem villi as well as a lower placental weight and birth weight. The reduction in the number of arteries seems to be due to an early developmental arrest of placental angiogenesis and is partly compensated for by increased formation of capillaries in the terminal villi, since the number of capillaries is independent of the number of arteries.

Umbilical venous pulsatility and volume blood flow in complicated pregnancies: Correlation with the umbilical artery blood velocity waveforms

The purpose of this retrospective work was to evaluate Doppler recorded umbilical venous volume blood flow in complicated pregnancies with abnormal umbilical venous pulsatility. During 1632 examinations abnormal pulsatility was found in 14 fetuses having normal volume flow. There were four perinatal deaths, all in pregnancies with absent blood velocity in the umbilical artery and abnormal umbilical venous pulsatility, suggesting that measurements of umbilical venous blood velocity should be included in the surveillance of pregnancies with absent diastolic blood velocity.

Complicated pregnancies

The search continues for improved methods of detection of fetal distress. This review discusses the use of cord blood erythropoietin, umbilical artery blood velocity waveform, continuous fetal heart rate monitoring, and fetal biophysical profile scoring in the detection of fetal distress. Also discussed are a number of situations where pregnancy is complicated by either obstetric conditions such as breech presentation, vaginal birth after previous caesarean section, or accompanying systemic disease, including previous organ transplantation, cardiac disease, and substance abuse among parturients.

Screening for fetal distress in labour using the umbilical artery blood velocity waveform

Screening for fetal distress in labour using the umbilical artery blood velocity waveform

Screening for fetal distress in labour using the umbilical artery blood velocity waveform.

To investigate the potential value of umbilical artery blood velocity wave-form measurement as a screening test for intrapartum fetal distress on admission to the labour ward. Prospective study drawn from the local population of pregnant women. The labour ward of the Princess Anne Hospital, Southampton, UK. 334 women with singleton pregnancies of at least 37 weeks gestation. Emergency caesarean section for fetal distress. There was a twelve-fold increase in the rate of emergency caesarean section for fetal distress (95% Confidence Interval (CI), 4.9-29) among women with a systolic/diastolic (S/D) ratio > or = 3.0, when compared to those with an S/D ratio of < 3.0 (P < 0.00001). Measurement of the umbilical artery blood velocity waveform compared favourably with admission cardiotocography. Umbilical artery blood velocity waveform analysis may be used to screen for fetal distress in labour and appears to be particularly sensitive to problems of placental origin. However, it is not likely to confer benefit in labour wards whose fetal heart rate monitoring policy is determined by pregnancy risk factors and admission cardiotocography.

Placental morphology in relation to umbilical artery blood velocity waveforms

The association between umbilical artery flow velocity waveforms, placental morphology and arterial vascular pattern was investigated in 30 pregnant women at risk for intra-uterine growth retardation. The blood velocity waveform was assessed in the umbilical arteries with pulsed Doppler ultrasound. Placentas from fetuses with an end-diastolic zero flow were small and thick with an extrachorial configuration, marginal cord insertion, magistral or mixed allantochorial vessel pattern and few cotyledons. The incidence and the extension of gross lesions were slightly increased in these placentas compared to placentas from fetuses with a normal S/ D ratio (peak systolic velocity/minimum diastolic velocity). Placentas from fetuses with an increased S/ D ratio (> +2SD) were large and thin with a high maximum diameter/maximum thickness ratio. Heavily smoking mothers were overrepresented in the group, with an increased S/ D ratio and corresponding SGA infants. End-diastolic zero flow in the umbilical artery was strongly correlated with placental developmental abnormalities.

Umbilical artery blood flow velocity waveforms in pregnancy complicated by diabetes mellitus

Umbilical artery blood velocity waveforms were recorded by a pulsed Doppler system in the third trimester of pregnancy in 16 diabetic women (12 class B, 1 class C, 3 class D) and the waveforms were analysed for resistance index (RI = peak systolic velocity minus end diastolic velocity/peak systolic velocity). There was no significant correlation between the RI values and either serum glucose (r = 0.385) or fructosamine levels (r = 0.380). However, the RI values were raised in two cases with serum glucose levels of over 300 mg/dl. With a fall in serum glucose levels, the RI values returned to the normal range. No abnormal umbilical artery velocity waveforms were found when the serum glucose level was below 200 mg/dl.

The influence of maternal exercise on the pulsatility index of the umbilical artery blood velocity waveform

Doppler bloodflow velocity measurements in the umbilical arteries are quite generally used as a parameter for obstetrical management, notwithstanding the fact that restricted knowledge is available about the physiological and pathophysiological mechanisms of human umbilical circulation. The possible effects of maternal haemodynamic changes on the fetal circulation are only scarcely investigated. In a prospective study the effect of maternal exercise on the Pulsatility Index (PI) values measured in the umbilical artery with a pulsed Doppler device was assessed to investigate the need of standardization with respect to maternal exertion. The studied group consisted of 23 women with uncomplicated pregnancies of various gestational age, who underwent a moderate strain. Statistical analysis showed no significant difference in FHR and PI values before and after exercise, so it is concluded that it is not necessary to introduce a period of rest to precede a Doppler investigation.

Umbilical artery blood velocity waveform analysis in predicting the small-for-dates fetus

Doppler umbilical artery blood velocity waveforms were recorded longitudinally in 78 randomly selected pregnancies. The waveform maximal (A) to minimal (B) Doppler shift frequency ratios were determined to provide a semi-quantitative measure of impedance to blood flow in the fetoplacental circulation. Fifty-eight of these pregnancies and their outcomes were normal. The A B ratios from this normal group were used to derive a normal range of this index throughout the second half of pregnancy. A further 45 pregnancies, also randomly selected, were studied once within 2 weeks of delivery. Using those measurements, plus those from the longitudinal groups sampled within 2 weeks of delivery, the predictive values of the A B ratio in detecting the small for gestational age fetus have been derived. The sensitivity of the umbilical artery A B ratio in predicting a small for gestational age infant within 2 weeks of delivery was 58% with a specificity of 94%. The positive test predictive value was 69% with a negative test predictive value of 90%. These predictive values are lower than those previously published, probably because high-risk pregnancies were over-represented in earlier studies. Waveform analysis within 2 weeks of delivery did, however, appear to identify fetuses destined to develop a range of perinatal problems. Large prospective studies are needed before the predictive value of Doppler waveform analysis is clarified.