Doppler assessment of the cardiac and uteroplacental circulations in normal and complicated pregnancies

Summary. Blood flow velocity waveforms were recorded in four sites in the fetal circulation in a series of 271 normal and 71 complicated pregnancies. The sites were the umbilical artery, the uterine artery branches in the placental bed, and distal to the two arterial valves in the heart. The blood flow through the arterial valves was added to estimate combined cardiac output. Normal ranges for values in all sites were established in our own series, and were similar to other published results. Abnormality of the waveform in the umbilical artery proved the most useful predictor of perinatal morbidity. Reversal of the normal pattern of increasing diastolic flow in the umbilical artery with advancing gestation was an important prognostic finding in the pregnancies studied serially. The combined cardiac output did not fall until late in the course of fetal compromise, and low values were seen only with an abnormal umbilical artery tracing.     

The effect of exercise on uteroplacental Doppler waveforms in normal and complicated pregnancies.

Animal studies have suggested a detrimental effect of exercise on uterine blood flow, but it is unclear whether the same responses occur in human pregnancy. Thirty-four women in the third trimester of singleton pregnancies underwent a bicycle exercise test during which a pulsed Doppler method was used to assess the response of the uteroplacental circulation. Twelve pregnancies were uncomplicated and the other 22 were complicated by hypertension, small for gestational age (SGA) fetus, or both. Exercise appeared to increase the pulsatility of the uteroplacental Doppler waveform in all cases. The changes in the waveforms were more exaggerated in the complicated pregnancies, particularly when the resting waveform had been abnormal. These changes indicate an increase in uteroplacental vascular resistance with exercise, suggesting a deleterious effect of physical exertion in the third trimester, particularly in the presence of hypertension or SGA fetus.     

Doppler ultrasound assessment of fetal and uteroplacental circulations in severe second trimester oligohydramnios

Summary. Doppler blood flow studies in 41 pregnancies with oligohydramnios in the second trimester found abnormal patterns in all 14 pregnancies with intrauterine growth retardation but in only one of nine pregnancies with premature rupture of the membranes, and one of 10 with fetal renal defects. Mixed patterns were found in a heterogeneous group of fetuses with other malformations or intrauterine infection. Unlike previous reports a diagnosis was achieved in all pregnancies, suggesting that Doppler studies should be an integral part of the antenatal investigation in such pregnancies.     

Uterine artery Doppler flow and uteroplacental vascular pathology in normal pregnancies and pregnancies complicated by pre-eclampsia and small for gestational age fetuses

This study was conducted to investigate the association between uterine artery Doppler flow patterns and uteroplacental vascular pathology in normal and complicated pregnancies in view of the recently described concept of heterogeneous causes of hypertensive pregnancy complications. Forty-three women whose pregnancies were complicated by pre-eclampsia, the HELLP (Haemolysis, Elevated Liver enzymes, Low Platelets) syndrome and/or small for gestational age (SGA) fetuses and 27 women with normal pregnancies undergoing elective caesarean section were included. We obtained uterine artery Doppler waveforms at a mean of 4 days before delivery. Placental bed biopsies were obtained at caesarean section and analysed for physiological changes and pathological changes. We found that abnormal uterine artery Doppler flow was strongly associated with pregnancy complications. Absence of physiological changes was seen in 58 per cent of complicated pregnancies and 40 per cent of normal pregnancies. Pathological changes were seen in 58 per cent of complicated pregnancies and 53 per cent of normal pregnancies; they occurred in spiral arteries with and without physiological changes, and there was no significant correlation to Doppler results. In conclusion, absence of physiological changes is associated with abnormal uterine artery Doppler flow and pregnancy complications. However, there is a gradient in the severity of uteroplacental vascular pathology and the correlation with pregnancy complications is not as strong as previously thought. There is also a significant degree of uteroplacental vascular pathology in normal pregnancies with normal uterine artery Doppler flow. This variation may be partly due to sampling error, as a typical biopsy contains only one or two spiral arteries. We hypothesize that additional factors might be necessary to induce the clinical syndrome of pre-eclampsia.     

Maternal blood viscosity and uteroplacental blood flow velocity waveforms in normal and complicated pregnancies

According to the Poiseuille-Hagen law, viscosity influences flow resistance. A possible effect of blood viscosity upon the resistance index of the uteroplacental circulation as measured by continuous wave Doppler ultrasound was investigated in 50 pregnant women. It was found that blood viscosity variables explained only about 10% of the variation in the resistance index in all patients, which was not statistically significant. It is suggested, therefore, that the vascular contribution to flow resistance may be more important.     

Maternal blood viscosity and uteroplacental blood flow velocity waveforms in normal and complicated pregnancies

Summary. According to the Poiseuille-Hagen law, viscosity influences flow resistance. A possible effect of blood viscosity upon the resistance index of the uteroplacental circulation as measured by continuous wave Doppler ultrasound was investigated in 50 pregnant women. It was found that blood viscosity variables explained only about 10% of the variation in the resistance index in all patients, which was not statistically significant. It is suggested, therefore, that the vascular contribution to flow resistance may be more important.     

Transvaginal color Doppler imaging in the assessment of uteroplacental blood flow in the normal first-trimester pregnancy

Characteristic changes of low resistance and high diastolic blood flow velocity were identified by Doppler studies starting in the early phase of the second trimester. These changes were attributed by some authors to trophoblastic invasion of the uterine vasculature converting the uterus into a low-resistance organ. Because of technical limitations previous studies were confined to the uterine artery and its main branches. With the development of color Doppler and transvaginal ultrasonography we can now identify blood flow in various small vessels in the placental bed. This study was performed to assess the ability of color Doppler ultrasonography to evaluate subtrophoblastic blood flow by color identification in the early phase of normal pregnancy from 5 to 9 weeks' gestation. Results show that the characteristic increase in diastolic blood flow is evident as early as 5 weeks' gestation.     

Assessment of uteroplacental circulation in uncomplicated pregnancies using pulsed Doppler ultrasound

The Doppler sonography enable as a new non-invasive procedure the assessment of the uteroplacental circulation. 209 blood flow measurements (pulsed wave Doppler) were recorded between the 20th and 40th weeks of gestation from the arcuate arteries in 130 women with uncomplicated pregnancy. The S/D Ratio, the Resistance Index (RI) and the Pulsatility Index (PI) were calculated. These Indices show throughout the observation time persisting low values which reflect the optimal uteroplacental circulation in a system with low downstream impedance. We found that the S/D Ratio and the RI are appropriate parameters in the qualitative analysis of the uteroplacental perfusion. On the other side we could demonstrate that the PI depends on the maternal heart rate which explains the high variability of the values. Therefore is the PI not appropriate for the impedance measurements in uteroplacental vessels.     

Fetal cerebral circulation assessment by Doppler ultrasound in normal and pathological pregnancies

During normal pregnancies (n = 40) the cerebral index (Rc = S - D/S) (with S = systolic and D-telediastolic amplitudes) is always higher than the placental index (Rp), and the cerebro/placental ratio (Rc/Rp) greater than 1. Of 29 pregnant women with hypertension (including two twins), 17 delivered normally (Rc, Rp and CPR normal), 14 delivered an hypotrophic fetus, in 12 out of these 14 pregnancies one of the two indices (Rc or Rp) was abnormal and the cerebro/placental ratio, CPR, was always less or equal to 1. CPR sensitivity was 86% the specificity 100%. In 11 pregnancies with idiopathic fetal-growth retardation, the CPR was less or equal to 1 in eight cases (73% of the cases), and greater than 1 in three cases (three false-negative results).     

Metabolic syndrome in normal and complicated pregnancies

OBJECTIVE: To evaluate the prevalence of metabolic syndrome and its components in normal and complicated pregnancies. STUDY DESIGN: Setting: university hospital, tertiary referral centre. Subjects: 90 pregnant women in four groups: 20 women with preeclampsia, 20 women with gestational hypertension, 30 women with late-onset gestational diabetes and 20 healthy pregnant women as a control group. Intervention: peripheral insulin resistance was measured by using the insulin tolerance test. Glucose, triglycerides, high-density lipoprotein cholesterol, blood pressure and body mass index were analysed. Comparisons were done by Chi-squared test, one-way analysis of variance and the Bonferroni's test. Prevalence of the metabolic syndrome was calculated by adapting both the WHO and the NCEP definitions of the metabolic syndrome to pregnancy. RESULTS: There were no cases of metabolic syndrome in the control group according to any of the adapted definitions. The prevalence of this syndrome was 3.3% and 10% in the late-onset gestational diabetes group, 35% and 20% in the gestational hypertension group and 30% and 30% in the preeclampsia group for the WHO and the NCEP definitions, respectively. CONCLUSIONS: Metabolic syndrome is present in about one-third of women with pregnancy-induced hypertension but only in 10% of women with late-onset gestational diabetes.     

Doppler assessment of the fetal asphyxia in pregnancies complicated by gestational hypertension and intrauterine growth retardation

OBJECTIVES: Gestational hypertension is associated with a high morbidity for both mother and fetus. Doppler ultrasound has allowed the fetal circulation to be examined. Now it is possible to monitor the response of the fetal circulation to hypoxia. DESIGN: The aim of this study was to determine flow patterns in fetal circulation from pregnancies complicated by gestational hypertension and intrauterine growth restriction. MATERIALS AND METHODS: The investigation included 23 fetuses with signs of the gestational hypertension and intrauterine growth restriction. We evaluated cerebral-placental ratio (CPR) and pulsation index (PI) in the middle cerebral artery (MCA) and the umbilical artery (UA). We also evaluated flows in umbilical vein. RESULTS: We observed abnormal flow pattern in all cases of analyzing fetuses. The most common abnormal flow was vein pulsation (48%). CONCLUSIONS: All analyzing fetuses shown signs of the hypoxia. Present of the umbilical vein pulsation or decompensate of the brain sparing effect is closely related o increased perinatal mortality.     

Transvaginal color Doppler assessment of the uteroplacental circulation in early pregnancy

Transvaginal color Doppler was used to investigate the uteroplacental circulation of 45 patients with normal intrauterine pregnancies at 4-18 weeks' gestation. The main uterine artery and the radial and spiral arteries were demonstrated, and characteristic flow velocity waveforms were obtained in more than 90% of cases. The indices of impedance to flow decreased with gestation and there was a progressive fall in these indices from the uterine artery, through the radial, to the spiral artery. Blood velocity in the uterine artery increased exponentially with gestation.     

Umbilical artery and uteroplacental velocimetry in pregnancies complicated by idiopathic low birthweight centile.

Umbilical artery and uteroplacental Doppler flow velocity waveforms were studied in 35 pregnancies complicated by idiopathic low birthweight centile. Thirty fetuses (86%) were below the 5th centile birthweight for gestation. Fifteen (43%) had an abnormal umbilical artery systolic to diastolic ratio. Uteroplacental waveforms were recorded in 29 of the 35 pregnancies and five (17%) showed an abnormal systolic to diastolic ratio. Abnormal uteroplacental systolic to diastolic ratios were associated with a significantly earlier gestational age at delivery and significantly more cesarean sections for fetal distress compared with normal uteroplacental systolic to diastolic ratios (p less than or equal to 0.01). The absence of umbilical artery end-diastolic frequencies was associated with a significantly earlier gestational age at delivery compared with the presence of umbilical artery end-diastolic frequencies (p less than 0.005). No differences in pregnancy outcome were observed comparing normal with abnormal amniotic fluid volume assessment. These findings suggest that Doppler studies may be useful in estimating the risk of adverse perinatal outcome for small for gestational age fetuses with no identifiable cause.     

Doppler systolic-diastolic ratios in pregnancies complicated by syphilis

Maternal infection with syphilis can result in focal areas of vasculitis and, similarly, placental villitis and obliterative arteritis. We hypothesized that Doppler systolic-diastolic ratios (S/Ds) in pregnancies complicated by maternal syphilis infection might reflect an increased resistance to placental perfusion. Doppler velocity waveform analysis was used to study the uterine and umbilical arteries in third-trimester pregnancies complicated by maternal syphilis infection. A control group of similarly studied normal pregnancies was used for comparison. Statistically significant increases were found in the mean S/Ds of both the uterine and umbilical arteries in the syphilis group compared with the normal group, indicating an increased resistance to perfusion of the placenta in pregnancies complicated by syphilis. This difference was even greater in association with the identification of spirochetes in the amniotic fluid by dark-field microscopy, indicating that the S/D results are related to the presence of intrauterine infection. Serial S/Ds in a small subgroup of patients correlated with the clinical courses, including an apparent acute vascular-resistance change associated with treatment, probably due to the Jarisch-Herxheimer reaction. Because of these post-treatment vascular events, the pre-treatment S/D alone may have a limited clinical predictive value for treatment efficacy in congenital syphilis.     

Umbilical coiling index in normal and complicated pregnancies

OBJECTIVE: To estimate the relation between undercoiling and overcoiling of the umbilical cord and adverse pregnancy outcome. METHODS: Umbilical cords and hospital records of 885 patients were studied in a cross-sectional study design. The umbilical coiling index was determined as the number of complete coils divided by the length of the cord in centimeters, blinded for pregnancy outcome. Obstetric history and pregnancy outcome of each patient were obtained from hospital records, blinded for the umbilical coiling index. Odds ratios and their 95% confidence intervals were calculated to evaluate associations between undercoiling and overcoiling and adverse pregnancy outcome, using multiple logistic regression. RESULTS: Undercoiling (umbilical coiling index below the 10th percentile, using references values from uncomplicated pregnancies) was associated with fetal death (odds ratio [OR] 3.35, 95% confidence interval [CI] 1.48-7.63), spontaneous preterm delivery (OR 2.16, 95% CI 1.34-3.48), trisomies (OR 5.79, 95% CI 2.07-16.24), low Apgar score at 5 minutes (OR 3.14, 95% CI 1.47-6.70), velamentous cord insertion (OR 3.00, 95% CI 1.16-7.76), single umbilical artery (OR 3.68, 95% CI 1.26-10.79), and dextral coiling (OR 1.80, 95% CI 1.02-3.17). Overcoiling (umbilical coiling index above the 90th percentile) was associated with asphyxia (OR 4.16, 95% CI 1.30-13.36), umbilical arterial pH < 7.05 (OR 2.91, 95% CI 1.05-8.09), small for gestational age infants (OR 2.10, 95% CI 1.01-4.36), trisomies (OR 9.26, 95% CI 2.84-30.2), single umbilical artery (OR 8.25, 95% CI 2.60-26.12), and sinistral coiling (OR 4.30, 95% CI 1.52-12.2). CONCLUSION: Undercoiling and overcoiling of the umbilical cord are associated with increased risk for adverse perinatal outcome.     

Effect of angiotensin II infusion during normal pregnancy on flow velocity waveforms in the uteroplacental and umbilical circulations

Women destined to develop preeclampsia show an increased systemic pressor response to infused angiotensin II, and the angiotensin sensitivity test has been accepted as an appropriate means of identifying these women. However, the effect of angiotensin II infusion on uteroplacental blood flow is unknown and may be deleterious. Patients undergoing angiotensin sensitivity tests as part of a protocol examining the effect of aspirin on the incidence of preeclampsia were studied with Doppler velocimetry performed before and during the angiotensin II infusion. Fetal well-being was documented with biophysical profiles performed before and after the infusions. Neither the systolic-diastolic ratios in the uterine and umbilical arteries nor the biophysical profile scores were altered significantly (P = .43, P = .23, Wilcoxon signed-rank median test, and P = .35, Fisher exact test, respectively). These findings suggest that the angiotensin sensitivity test does not increase resistance to flow in the uterine or umbilical circulation, and therefore may be used safely in screening for preeclampsia.