Uterine artery Doppler velocimetry in pregnant women with hypertension

Clinical significance of early diastolic notch depth: uterine artery Doppler velocimetry in the third trimester

OBJECTIVE

Our purpose was to evaluate the usefulness of early diastolic notch depth in predicting adverse perinatal outcome.

STUDY DESIGN

Uterine artery Doppler velocimetry is widely applied in predicting pregnancy outcomes. Recent studies of uterine artery early diastolic notch have demonstrated its usefulness as a marker for fetal well-being. The early diastolic notch represents the reflected blood flow of uteroplacental circulation. This study was carried out under the hypothesis that when early diastolic notch is present evaluating its depth plays a significant role in predicting poor pregnancy outcomes. Its ability to predict adverse perinatal outcomes was evaluated in 198 pregnant women with early diastolic notch after 28 weeks' gestation.

RESULTS

The incidence of adverse perinatal outcome (5-minute Apgar score <7, cesarean delivery because of fetal distress, admission to neonatal intensive care unit, fetal growth restriction, or perinatal death) was 90.5% when the notch index was </=0.70. When the notch index range was 0.70 to 0.79, 0.80 to 0.89, and >/=0.90, the respective incidences were 72.3%, 46. 9%, and 28.1%.

CONCLUSION

This study suggests that evaluating notch depth in the presence of early diastolic notch on uterine artery velocimetry during the third trimester would be a useful method for predicting adverse perinatal outcomes.

Doppler sonographic findings for hypertension in pregnancy and HELLP syndrome

Doppler examinations of the umbilical artery, both uterine arteries, and the fetal middle cerebral artery were performed in the third trimester in 18 patients with pregnancy induced hypertension, 52 patients with preeclampsia, and 32 patients with HELLP syndrome and the results were correlated with the parameters fetal outcome. For 74% of the patients this was the first pregnancy, in 93% of the cases a cesarean section was necessary; 66% of the newborn babies were dystrophic and 90% of them were born prematurely. The blood flow in one uterine artery was restricted in 95% of all 102 pregnant women, only 5% did not show any pathological findings. A pathological blood flow was observed on Doppler sonography in the umbilical artery in 70% of the group and 39% showed a pathologically increased perfusion of the fetal middle cerebral artery. The average birth weights and gestational ages in the study group were markedly reduced in comparison with healthy pregnant women (pregnancy induced hypertension: 1620 g/35 weeks; preeclampsia: 1660 g/34 weeks; HELLP syndrome: 1160 g/31 weeks, respectively). The lowest values for average birth weight and gestational age occurred when all four investigated blood vessels showed pathological Doppler findings: 1180 g/31 weeks (0 to 1 pathological vascular findings: 2780 g/38 weeks; 2 pathological vascular findings: 1845 g/34.5 weeks; 3 pathological vascular findings: 1330 g/31 weeks). This Doppler study underlines the importance of examining four blood vessels: the uterine, the umbilical, and the fetal middle cerebral arteries for a complete analysis of the fetoplacental hemodynamics. On account of the severely impaired hemodynamics observed in the placentas of our patients with hypertensive diseases in pregnancy or HELLP syndrome, we believe the early diagnosis of these disorders by Doppler sonography and an early start of therapy to be essential.

Mid-trimester uterine artery Doppler screening as a predictor of adverse pregnancy outcome in high-risk women

OBJECTIVE

To assess the value of uterine artery Doppler ultrasound screening, when performed in a clinical setting, to predict complications of impaired uteroplacental blood flow in high-risk women.

DESIGN

A prospective audit.

SUBJECTS

A total of 116 pregnancies in 114 women at high risk of pre-eclampsia and/or small-for-gestational-age (SGA) babies attending a maternal-fetal medicine clinic at National Women's Hospital, a tertiary referral hospital, Auckland, New Zealand.

METHODS

Uterine artery Doppler screening was performed as part of clinical practice between 22 and 24 weeks' gestation. A resistance index (RI) was calculated from each uterine artery and the presence or absence of a notch was determined. An RI of > 0.58 was defined as abnormal and an RI of > or = 0.7 was defined as very abnormal. The main outcome measures were: pre-eclampsia, SGA baby (birth weight < 10th centile), placental abruption, intrauterine death, 'all' and 'severe' outcomes.

RESULTS

Thirty-two (27.5%) women developed pre-eclampsia, 31 (26.7%) had SGA babies, 23 (20%) were delivered at < 34 weeks because of pregnancy complications, and there were three (2.6%) placental abruptions and three (2.6%) perinatal deaths. The sensitivity of any RI of > 0.58 for pre-eclampsia, SGA, 'all' outcomes and 'severe' outcome was 91%, 84%, 83% and 90%, respectively. The specificity of any RI of > 0.58 for these outcomes was 42%, 39%, 47% and 38%, respectively. The positive predictive value of any RI of > 0.58 for the same outcomes was 37%, 33%, 58% and 24%, respectively. Among women with both RI values of > or = 0.7, 58%, 67%, 85% and 58% developed pre-eclampsia, SGA, 'all' and 'severe' outcomes, respectively. In women with bilateral notches, 47%, 53%, 76% and 65% developed the respective outcomes. Women with both RI values of > or = 0.7 and women with bilateral notches had relative risks of 11.1 (95% CI 2.6-46.4) and 12.7 (95% CI 4.0-40.4) for developing severe outcome, respectively. Only 5% of women with both RI values of < 0.58 developed a severe outcome.

CONCLUSION

In high-risk women, uterine artery Doppler waveform analysis performed best in the prediction of severe adverse outcome and was better than clinical risk assessment in the prediction of pre-eclampsia and SGA babies. Further studies are necessary to determine how information from uterine artery Doppler studies should modify current practice in high-risk women.

Severe uterine diastolic notch as a prognostic factor in preeclamptic women

OBJECTIVE

To investigate the usefulness of grade II uterine diastolic notch to predict maternal or perinatal outcome during conservative management of preeclampsia.

STUDY DESIGN

We reviewed medical charts of 35 pregnant women admitted for hypertension and > or =1+ urine dipstick protein determination and who had a uterine Doppler examination at admission. Grade I notch was defined as a 'nadir' in early diastole higher than half of peak diastolic notch velocity. Grade II diastolic notch was defined as a 'nadir' in early diastole lower than half of peak diastolic notch velocity.

RESULTS

Thirty-one preeclamptic women were admitted at 30.1+/-3 weeks. Of them, 23 had a grade I notch (group I) and eight a grade II notch (group II). Rates of abruptio placenta, eclampsia, thrombocytopenia, stillbirth, birth weight < or = 3rd centile, fetal distress before delivery and neonatal death were similar in the two groups. Rates of delivery before 32 weeks and newborn spending more than 48 h in neonatal intensive care unit were significantly higher in group II. Admission-to-delivery interval was significantly lower in group II (2.6+/-1.5 vs. 9.4+/-8.7 days, P<0.05).

CONCLUSION

Grade II notch seems to identify in preeclamptic women those with a higher risk of early pregnancy termination.

Prediction of preeclampsia

The onset of preeclampsia at or near to term is associated with low maternal and neonatal morbidity and mortality. In contrast, those patients (1%) who suffer early onset preeclampsia engender significant maternal and perinatal morbidity and mortality. Therefore, because of the lack of proven prophylaxis for preeclampsia, prediction of risk or identification of subclinical disease is desirable to identify patients for more intensive observation. There are certain at-risk groups of patients such as those with chronic hypertension, pregestational diabetes, multifetal gestation, and previous preeclampsia. These patients account for the majority of cases of preeclampsia in multiparas, yet only account for 14% of preeclampsia in nulliparous women. Thus, the majority of cases of preeclampsia arises from nulliparous women without medical complications at low risk. Differences in the time of onset, severity, and organ system involvement suggest there may be different underlying etiologies that ultimately lead to preeclampsia manifested as the triad of maternal hypertension, proteinuria, and edema. Distinct markers therefore may identify subgroups of at-risk patients with separate underlying causes. These markers ultimately could be used for diagnosis of disease before the clinical appearance of maternal disease (hypertension, proteinuria, and edema). Based on data from patients with established disease, with the involvement of various organ systems, potential candidate markers would include renal function (kallikrein-creatinine); coagulation and fibrinolytic systems and platelet activation (platelet volume); markers of vascular function (fibronectin, prostacyclin, thromboxane) and oxidant stress (lipid peroxides, 8-isoprostane, antioxidants, anticardiolipin antibodies, hemoglobin, iron, transferrin, homocysteine, hypertriglyceridemia, albumin isoforms); placental peptide hormones (CRH, CRHbp, activin, inhibin, hCG); vascular resistance (uteroplacental flow velocity waveforms); genetic markers; insulin resistance; and glucose intolerance. Although cross-sectional studies have identified these potential markers, they need to be evaluated in prospective longitudinal studies with rigorous definition of outcome to determine if they are useful in predicting preeclampsia and whether they can identify different subgroups of patients.

Forty years of obstetric ultrasound 1957-1997: from A-scope to three dimensions

In this article, we record the history of obstetric ultrasound as it developed worldwide in the second half of the twentieth century. The technological advances during this period saw the evolution of equipment from the original adapted metal flaw detectors producing a simple A-scan to the modern, purpose built, real-time colour flow machines with three-dimensional capability (Fig. 1). Clinically, ultrasound began as a research tool, but the poor quality of the images led to the ridicule of many of the early investigators. However, because of their perseverance, ultrasound developed into an imaging modality providing immense diagnostic capabilities and facilitating with precision many invasive procedures, diagnostic and therapeutic, both of which have made significant contributions to patient care. In this history, we recall the people, the personalities, and the problems they encountered during the development of ultrasound and how these problems were resolved, so that ultrasound now is available for use in the care of pregnant women throughout the developed world.

Significance of a diastolic notch in the uterine artery flow velocity waveform induced by uterine embolisation in the pregnant ewe

OBJECTIVE

To investigate the relation between placental embolisation and the diastolic notch in the uterine artery flow velocity waveform of pregnant ewes under general anaesthesia.

METHODS

Seven pregnant ewes at a gestation 16 to 17 weeks were anaesthesized and microbeads of gelfoam were injected into the uterine artery; changes in the uterine circulation were assessed by Doppler velocimetry.

RESULTS

Gelfoam embolisation reduced uterine blood flow in a dose-dependent manner, from a mean (95%, CI) of 568 mL/min (495-641) to 159 mL/min (131-187) after the injection of 30 mg of gelfoam, and increased the uterine vascular resistance from 135 mmHg x min x L(-1)(103-167) to 498 mmHg x min x L(-1) (422-574). A diastolic notch in uterine artery flow velocity waveform was observed after 20 mg to 25 mg of gelfoam in two ewes and after injection of 30 mg of gelfoam in all seven animals. Injection of 30 mg of gelfoam increased the pulsatility index to 2.4 (1.9-2.9) from 0.6 (0.5-0.7). The mean uterine vascular resistance at the time of the appearance of a diastolic notch was 414 mmHg x min x L(-1)(377-451).

CONCLUSION

These findings suggest that an elevated pulsatility index and the presence of a diastolic notch in the uterine artery flow velocity waveform are indicators of increased uterine vascular resistance and impaired uterine circulation.

Role of uterine artery Doppler investigation in pregnant women with chronic hypertension

OBJECTIVE

To evaluate the role of uterine artery Doppler investigation in predicting perinatal outcome of patients with chronic hypertension.

STUDY DESIGN

Uterine artery velocimetry was investigated at 24 weeks gestation in 78 chronic hypertensive pregnant women by means of color Doppler. The resistance index (RI) and the presence of a diastolic notch were recorded and related to the development of superimposed preeclampsia (SPE), pregnancy aggravated hypertension (PAH). and intrauterine growth retardation (IUGR).

RESULTS

There were more pregnancy complications in the 25 patients with abnormal RI, compared with the 53 women with normal RI (SPE 12% vs. 0%, PAH 36% vs. 7% and IUGR 52% vs. 2%; P<0.01), and more in women with a bilateral diastolic notch compared with those without (SPE 23% vs. 0, PAH 54% vs. 4%, IUGR 85% vs. 2%; P<0.0001), while no differences were detected in those with only a unilateral notch, except for PAH (27% vs. 4%; P<0.01).

CONCLUSION

Uterine artery Doppler velocimetry identifies a subgroup of chronic hypertensive patients with a high frequency of pregnancy complications.

Feto-maternal circulation: mathematical model and comparison with Doppler measurements

OBJECTIVES

Clinicians are more and more frequently studying fetal blood flow velocity curves recorded by Doppler ultrasound in vital organs such as the placenta and fetal brain to evaluate fetal well-being. We have therefore developed a mathematical model of the utero-placental and fetal circulations which could be used for teaching and for a better understanding of regulatory mechanisms.

METHODS

The model is based on two basic elements-an arterial segment and a bifurcation-and we have reproduced the major arteries of the feto-maternal circulation combining these basic elements. The mathematical model of the system is based on the Navier-Stokes equations. The peripheral areas such as the brain, kidneys and placenta are modeled by a simple Windkessel model and the model computes instantaneous flow and pressure at any point in the fetal arterial tree and the uterine arteries.

RESULTS

We have compared the computed instantaneous flow curves and pressure with in vivo data and our results agree with the findings in physiological situations and in gravidic hypertension.

CONCLUSIONS

Our model provides new interesting insights into fetal hemodynamics such as a better understanding of the mismatch impedance phenomena and is a promising model for the study of blood redistribution mechanisms in hypoxic situations.

Transvaginal Doppler ultrasound of the uteroplacental circulation in the early prediction of pre-eclampsia and intrauterine growth retardation

OBJECTIVE

To evaluate the predictive value of transvaginal Doppler ultrasound studies of the uterine and umbilical arteries in early pregnancy, in identifying pregnant women at risk of subsequently developing pre-eclampsia, or the delivery of a small for gestational age infant.

DESIGN

A multivariate logistic regression of Z scores of Doppler indices obtained from the uterine and umbilical arteries of 652 women with singleton pregnancies at 12 to 16 weeks of gestation. Measurements included the presence or absence of a notch, bilateral (right and left waveform) notching, vessel diameter, the resistance index, the pulsatility index, time averaged mean velocity (cm/s), maximum systolic velocity (cm/s), and volume flow (mL/min). Stepwise logistic regression and multivariate analysis of all the parameters measured was used to construct several scoring systems.

MAIN OUTCOME MEASURES

Pre-eclampsia, birthweight, preterm delivery.

RESULTS

In women that developed complications, there was a trend towards increased resistance and reduced velocity and volume flow. If bilateral notches were present there was an increased risk of pre-eclampsia (odds ratio [OR] 21.99, 95% CI 6.55-73.79), premature delivery (OR 2.38, 95% CI 1.19-4.75), and the delivery of a small for gestational age baby (OR 8.63, 95% CI 3.95-18.84). Using multivariate analysis, a seven parameter model was selected (after removal of vessel diameter, uterine and umbilical resistance index). This model produces a scoring system with a sensitivity of 92.9% and a specificity of 85.1% for the prediction of pre-eclampsia. A three parameter model (bilateral notches, uterine resistance index, umbilical pulsatility index) provides similar sensitivities, but lower specificities, when compared with the seven parameter model.

CONCLUSION

These data indicate that there are differences in uterine and umbilical artery Doppler blood flow indices at 12 to 16 weeks, in pregnancies with a normal or complicated outcome. Scoring systems derived from multivariate analysis of Doppler indices demonstrate the potential of being able to identify, in early pregnancy, a group of women at increased risk of the subsequent development of pre-eclampsia, premature delivery, or the birth of a small for gestational age baby.

The effect of nitric oxide on uterine and umbilical artery flow velocity waveform in pre-eclampsia

We compared the flow velocity waveforms of uterine and umbilical arteries in normotensive and pre-eclamptic patients at mid-gestation. In a randomised controlled trial we tested the effects of isosorbide dinitrate (ISDN, nitric oxide donor) patch therapy on the flow velocity waveform of pre-eclamptic patients at mid-gestation. The resistance indices (RI) of human uterine and umbilical arteries were higher in pre-eclamptic patients compared to the normotensive patients. ISDN patch therapy significantly reduced the increased RI values of the umbilical artery in pre-eclamptic patients without any change in systemic blood pressures, but the RI values of the uterine artery were not significantly attenuated. The change of the umbilical artery might be due to the improvement of end-diastolic flow velocity. These results suggest that the feto-placental circulation in pre-eclampsia, perhaps due to the disturbance of the endothelium-dependent vaso-relaxation system, and that ISDN therapy may improve the impaired endothelium dependent nitric oxide system.

Doppler velocimetry of the uterine arteries in nulliparous women

The aim of this study was to evaluate the role of uterine artery Doppler velocimetry performed at 20 and 24 weeks gestation in predicting gestational hypertension and small-for-gestational age babies in a population of nulliparous women. Four hundred and fifty-six patients without risk factors for pregnancy complications and with fetuses free from structural abnormalities at ultrasonographic examination at 20 weeks gestation were considered in the study. During the routine 20 weeks ultrasound a continuous-wave Doppler examination of the uterine arteries was performed. The patients with abnormal uterine Resistance Index (RI) repeated the Doppler evaluation at 24 weeks by means of Colour Doppler equipment. Among the 419 women who completed the study an abnormal Doppler uterine arteries velocimetry was found in 8.6% of the patients. Pregnancy complications (gestational hypertension and/or small-for-gestational age babies) were observed in 56% of the patients presenting high uteroplacental RI versus 10% of those with normal uterine artery velocimetry (P = 0.0001). In the group of patients with an abnormal RI value, the presence of a diastolic notch in one or both of the uterine arteries identified a population of pregnant women at higher risk for pregnancy complications when compared with patients without notch (78% vs. 33%, P = 0.007). The knowledge of the uteroplacental resistance can help in identifying a subgroup of patients at higher risk of hypertensive disorders and small-for-gestational age babies that could benefit from prophylaxis with low dose aspirin.

Fetal redistribution of blood flow and amniotic fluid volume in growth-retarded fetuses

Our purpose was to assess the relationship between the fetal redistribution of blood flow and the amount of amniotic fluid in appropriate-for gestational-age fetuses and growth-retarded fetuses. Blood flow velocity waveforms of the umbilical artery, descending aorta, middle cerebral artery, renal artery and uterine artery were recorded using pulsed Doppler ultrasonography in 100 appropriate-for gestational age fetuses and 39 growth-retarded fetuses. The pulsatility index (PI) values and the amount of amniotic fluid were compared between the two groups. The PI values of the umbilical artery and renal artery were significantly higher in appropriate for gestational-age-fetuses with oligohydraminos than in fetuses with an adequate amount of amniotic fluid. The PI values of the umbilical artery and renal artery were significantly higher and the PI of the middle cerebral artery was significantly lower in growth-retarded fetuses with oligohydramnios than in fetuses with an adequate amount of amniotic fluid. Furthermore, there was a significant negative correlation between the PI value of the renal artery and the vertical diameter of amniotic fluid, and between the PI value of the renal artery and the amniotic fluid index. The PI value of the renal artery was related to the amount of amniotic fluid in growth-retarded fetuses, and the same relationship was demonstrated in appropriate-for gestational age fetuses.

Uterine artery Doppler velocimetry in pregnant women with lateral placentas

The aim of this study was to compare the efficacy of placental, non-placental, mean of both uterine arteries Doppler velocimetry at 22-24 weeks gestation in the prediction of pregnancy induced hypertension (PIH) and intrauterine growth retardation (IUGR). Flow velocity waveforms were obtained by means of color and pulsed Doppler in 481 patients with lateral placentas at 22-24 weeks gestation. Placental location was determined by real time ultrasonography. Comparisons were performed between controls and pregnancies complicated by PIH and IUGR. Sensitivities, false positive rates and positive predictive values for PIH and IUGR of resistance indices (RI) above the 90th percentile, and diastolic notches in placental, non-placental or both uterine arteries were calculated. A mean uterine artery RI > or = 0.66 (90th centile) had better sensitivity than the placental (26.8% vs 17.1% for IUGR and 41.7% vs 33.3% for PIH) and the non-placental uterine artery (26.8% vs 21.9% for IUGR and 41.7% vs 33.3% for PIH). The presence of a diastolic notch in the placental uterine artery increased sensitivity (31.7% for IUGR and 50.0% for PIH) and positive predictive value of the test. In patients with laterally implanted placentas a mean of both uterine arteries RI above the 90th centile and the presence of a diastolic notch in the placental uterine artery at 22-24 weeks have a higher predictive value for the subsequent development of PIH and IUGR than the separate evaluation of the 2 uterine arteries.

The hemodynamics of the umbilical artery in normal and pre-eclamptic pregnancies. A new application of SQUID biomagnetometry

This study was set to investigate the hemodynamics of the feto-placental circulation in normal and pre-ecclamptic pregnancies using the biomagnetometer SQUID. Thirteen women with pre-eclampsia and 26 healthy women were studied. All were "near term". Biomagnetic signals (waveforms) were recorded from the umbilical arteries. After statistical Fourier analysis, the findings were assigned arbitrarily in terms of spectral amplitudes as high (200-300 fT/ root of Hz), low (80-150 fT/ root of Hz) and borderline (151-199 fT/ root of Hz). In all cases the frequencies considered were distributed in the range 2-7 Hz. Interestingly, the umbilical artery waveforms and the corresponding spectral densities were of high amplitudes in most (88%) normal pregnancies of low amplitudes in most (84.6%) pregnancies complicated with pre-eclampsia. These findings were of statistical significance and were correlated with fetal heart rate (FHR) monitoring, pH and Apgar score at 1 and 5 minutes; high amplitude cases were related with normal FHR monitoring, pH > 7.25 and Apgar score > 7, while low amplitude recordings were connected with abnormal FHR patterns, pH < 7.25 and Apgar score < 7. It is suggested that biomagnetic measurements of the umbilical artery flow, which is an entirely new application of SQUID technology, is a promising procedure in assessing fetal health, especially in high risk pregnancies.

Peak systolic over protodiastolic ratio as an objective substitute for the uterine artery notch

OBJECTIVE

To measure the inter-rater agreement for the identification of a uterine artery notch, as well as the association between an observed notch and the peak systolic over protodiastolic (A/C) ratio.

DESIGN

Cohort study.

SETTING

Tertiary care university hospital.

POPULATION AND METHODS

Six hundred and sixty-five nulliparous women in whom 1022 examinations of uterine artery velocity waveforms were performed by pulsed Doppler at 18 and at 26 weeks of gestation. Agreement between two independent raters was analysed using Cohen's kappa statistics. A/C ratios of flow velocity waveforms with or without a notch were compared. The agreement between A/C values and the presence of a notch was estimated by measuring the surface under the receiver operating characteristic (ROC) curve.

RESULTS

Inter-rater agreement for the identification of a notch was 0.74 (95% CI 0.64-0.83) at 18 weeks and 0.72 (95% CI 0.64-0.80) at 26 weeks. A/C ratios were higher when a notch was present (P < 0.0001). The area under the ROC curve was 0.86 (95% CI 0.81-0.91) for the placental uterine artery and 0.93 (95% CI 0.90-0.96) for the nonplacental artery. An A/C value > or = 2.5 in any uterine artery had a sensitivity of 88% and a specificity of 86% to detect a notch.

CONCLUSION

Although there is no definitive definition of the notch, its detection is reproducible within a center. However, published prevalences between centers in unselected populations vary. The measure of the A/C ratio can serve as an objective substitute.

Chronic hypertension in pregnancy: color Doppler investigation of uterine arteries as a predictive test for superimposed preeclampsia and adverse perinatal outcome

To determine if uterine artery Doppler velocimetry is useful in identifying chronic hypertensive pregnancies at risk for superimposed preeclampsia and adverse perinatal outcome. Resistance index (RI) was assessed by color velocimetry at the level of uterine arteries at 23-24 weeks of gestation in 42 women with chronic hypertension. The "lowest", the "highest" and the "average" values were compared to select the most predictive index for superimposed preeclampsia, intrauterine growth retardation (IUGR), birth weight lower than 2500 g and gestational age at delivery less than 36 weeks. Nine patients developed superimposed preeclampsia (21%) and 15 delivered before the 36th week of gestation (36%); 4 babies were IUGR (10%) and in 18 cases birth weights were below 2500 g (43%). Statistical analysis of Doppler findings showed that abnormal values of "lowest RI" were significantly correlated with adverse pregnancy outcome. Color Doppler analysis of uterine arteries is able to select chronic hypertensive pregnant women at risk of superimposed preeclampsia and poor perinatal outcome.

Absence of relaxation to lactate in human placental vessels of pregnancies with severe preeclampsia

OBJECTIVE

Our objective was to determine whether the observed relaxation to lactate and other agents in placental vessels of normal pregnancies is altered in severe preeclampsia.

STUDY DESIGN

Isolated placental arteries and veins from women with severe preeclampsia and uncomplicated term pregnancies were precontracted with prostaglandin F2 alpha under 5% oxygen and 5% carbon dioxide with the balance nitrogen (Po2 35 to 38 torr) and then exposed to lactate (1 to 10 mmol/L, pH 7.4, n = 8 to 15), arachidonic acid (0.01 to 10 mumol/L, n = 6 to 13), nitroglycerin (1 nmol to 1 mumol/L, n = 4 to 12), or forskolin (0.01 to 10 mumol/L, n = 6 to 9). The response to lactate was also examined in placental vessels from appropriate-for-gestational-age preterm deliveries (n = 8) for comparison with a similar group with severe preeclampsia (n = 8). The t test and analysis of variance statistics were used.

RESULTS

Relaxation to lactate was markedly inhibited in both placental arteries and veins of women with severe preeclampsia compared with vessels from uncomplicated term or preterm pregnancies. Responses to the other relaxing agents were not altered in the severely preeclamptic vessels.

CONCLUSIONS

In severe preeclampsia absence of lactate-induced dilatation of placental vessels may contribute to the fetal complications associated with impaired blood flow and vasospasm.

Color Doppler ultrasonography and serum CA 125 in the differentiation of benign and malignant ovarian tumors

Color Doppler ultrasonography and serum CA 125 were used to evaluate 114 adnexal tumors prior to surgery. Six patients were excluded from this study because of ovarian cancer, borderline ovarian malignancy, and tubal gestation. A total of 108 patients were eligible: 83 patients with benign and 25 patients with malignant ovarian tumors. Resistance index (RI) was used to determine the peripheral resistance of intratumoral vessels. The cutoff point for the RI was defined as 0.5. The blood flow was considered to be normal when the RI was greater than 0.5 and abnormal when it was less than 0.5. The blood flow was detected in 100% of malignant tumors and 59% of benign tumors. The initial cutoff value for CA 125 was 35 U/mL. Sensitivity, specificity, positive predictive value, and negative predictive value were compared in terms of RI, serum CA 125, and a combination of the two. Our conclusion is that the combination of RI and CA 125 gives a sensitivity of 100% and negative predictive value of 100%. If the cutoff point of CA 125 was raised from 35 to 65 U/mL, then a specificity of 100% and positive predictive value of 100% were also attained with the use of RI and CA 125 without changes in sensitivity or negative predictive value. We conclude that the combination of color Doppler ultrasonography and serum CA 125 is an effective method to differentiate benign from malignant ovarian tumors.

The effect of acute volume expansion and vasodilatation with verapamil on uterine and umbilical artery Doppler indices in severe preeclampsia

Preeclampsia is associated with increased peripheral, uterine, and umbilical artery resistance. Acute blood pressure reduction may result in shunting of blood and sudden fetal distress. We therefore investigated the effects of volume expansion and verapamil therapy on uteroplacental and umbilical resistance during treatment of preeclampsia.

MATERIALS AND METHODS

Five severe preeclamptics underwent volume expansion and subsequent vasodilatation with an infusion of verapamil. Invasive hemodynamic monitoring and Doppler ultrasonography were used to study changes in maternal, uterine, and umbilical hemodynamics.

RESULTS

Volume expansion and subsequent verapamil therapy was associated with significant changes in maternal hemodynamics without significant change in uteroplacental or umbilical resistance. Uterine artery waveform changes were noted, with disappearance of notching in some cases.

CONCLUSIONS

Volume expansion and verapamil therapy effectively reduces maternal blood pressure in preeclampsia, without adversely affecting uteroplacental or umbilical artery resistance. Uterine artery waveform changes may be associated with improved fetal outcome.

Doppler flow velocimetry of the uterine and uteroplacental circulation in pregnancies complicated by insulin-dependent diabetes mellitus

In forty-three pregnancies complicated by insulin-dependent diabetes mellitus, 16 classified White B, 11 White C, 8 White D and 8 White R or F, the resistance-index (PR index) in the main part of the uterine artery and arcuate uterine arteries was measured by duplex-pulsed wave Doppler ultrasound. Recordings of 24 hours' blood glucose profile and glycosylated hemoglobin were parameters of glycemic control. Vascular resistance in the main uterine artery decreased with proceeding gestation as a non-diabetic pregnancy. The uterine artery supplying the placental had lower resistance than the opposite side, with a mean PR index of 0.559 (SD 0.117) and 0.622 (SD 0.133), respectively. The mean difference between both sides was 0.062 (SD 0.102) (p < 0.001). The uterine artery PR index was slightly higher in the presence of evident morphological vasculopathy, with a mean PR index of 0.591 (SD 0.104) in White D*/R/F diabetics and 0.545 (SD 0.063) in White B/C/D#, respectively (p = 0.148). Additionally more than half of the diabetics without manifest complications (B/C/D#) showed a persistent notch. Long- and short-term glycemic control was unrelated to vascular resistance in the uterine artery, with correlation coefficients of 0.027 (p = 0.746) and 0.051 (p = 0.537) for glucose and HbA1C, respectively. Doppler velocimetry could not predict diabetic specific fetal mobidity. Vascular resistance in the uterine arcuate arteries was significantly lower in the subplacental region, with a mean PR index of 0.367 (SD 0.056) compared to 0.427 (SD 0.064) in areas distant to the placenta (p < 0.0005). It was not related to vasculopathy elsewhere.

IN CONCLUSION

in patients with diabetic vasculopathy the uterine artery is also affected, but there is no relationship with long- or short-term parameters of glycemic control. Doppler flow velocimetry of the uterine artery is a poor predictor of diabetes-specific fetal morbidity; if normal ranges of non-diabetic pregnancies are used for reference. Because of significantly different vascular resistance in the two main uterine arteries, mean values of both-side measurements should be used for analysis, whenever possible.

Fetal and uteroplacental flow velocity waveforms in abruptio placentae: report of two cases

This paper reports two cases of abruptio placentae assessed using pulsed Doppler at 29 and 30 weeks of gestation. Transvaginal pulsed Doppler showed abnormal uterine artery FVWs in both cases. One fetus with normal umbilical and normal middle cerebral artery FVWs was not acidotic and only midly hypoxic, whereas the other fetus with normal umbilical and abnormal middle cerebral artery FVWs was severely acidotic and hypoxic at birth. It is suggested that Doppler assessment of fetal blood distribution is of great value for the rapid diagnosis of fetal asphyxia, and that uteroplacental FVWs provide reliable information on which to base the diagnosis of abruptio placentae.

Doppler ultrasound screening as part of routine antenatal scanning: prediction of pre-eclampsia and intrauterine growth retardation

OBJECTIVE

To assess the value of incorporating continuous wave Doppler ultrasound of the uterine arteries into the routine scan as a screening test in an unselected population.

DESIGN

A cross sectional study by multiple operators using continuous wave Doppler ultrasound to obtain flow velocity waveforms (FVW) from both uterine arteries of all women attending for routine anomaly scan at 18 to 22 weeks over a period of 12 months. An abnormal FVW in either uterine artery was used to predict intrauterine death, antepartum haemorrhage and three different degrees of severity of pre-eclampsia and growth retardation, singly and in combination.

SETTING

King's College Hospital, London.

SUBJECTS

Two thousand, four hundred and thirty women attending for routine anomaly ultrasound scan.

RESULTS

A total of 2430 women were scanned with a 90% follow up rate. The results demonstrate higher sensitivities than previous studies, but with a high proportion of false positive tests. By including an early diastolic notch in the definition of an abnormal FVW the prediction of pre-eclampsia is markedly improved; the relative risk to a woman with an abnormal waveform of developing moderate or severe pre-eclampsia is increased 24-fold. Although the positive predictive value for babies less than the 5th centile for gestation is only 15%, those at risk of neonatal complications may be identified.

CONCLUSION

This simple test can be performed at a routine visit and a group of women can be identified for further assessment and possible therapeutic intervention.

The relationship of uterine and umbilical Doppler resistance to fetal and placental protein synthesis in the second trimester

The relation of uteroplacental and umbilical Doppler resistance index (RI) to peripheral levels of alphafetoprotein (AFP), human chorionic gonadotrophin (hCG), human placental lactogen (HPL), Schwangerswaft protein (SP1), pregnancy-associated placental protein A (PAPP-A) and insulin-like growth factor binding protein 1 (IGP-BP1) at 16-24 weeks was established in a cross-sectional study of 183 unselected singleton pregnancies. There was an association between high values of uteroplacental RI and high hCG levels, and high umbilical RI values with high hCG and HPL levels. Thus, in the mid-trimester, the levels of some placental proteins seem to be related to placental resistance.

Quantitative characterization of arcuate artery hemodynamic change in normal pregnancy with Doppler ultrasonography

Using color and pulsed Doppler ultrasonography, arcuate arterial velocimetry was carried out in 91 normal women, at 16-40 weeks, menstrual age. The arcuate arterial hemodynamics was assessed by the calculation of the resistance index (RI). A curvilinear relationship was found between the RI value of the arcuate artery obtained from the placental site in the uterus and menstrual age (R2 = 0.328). The relationships between the RI value of the arcuate artery obtained from the nonplacental site (R2 = 0.268) or the averaged RI value between the placental and nonplacental sites (R2 = 0.321) and menstrual age were both linear. Normal ranges of RI values of arcuate arteries during pregnancy for the placental site, nonplacental site, and their average values were generated. These results provide a foundation for evaluating uteroplacental velocimetry in normal pregnancy using Doppler ultrasonography.

Doppler velocimetry in pregnancy

Since the late 1970s, Doppler velocimetry has been investigated extensively for use in obstetrics. Initially, this technique showed promise for the management of certain complications of pregnancy; this promise has yet to be fulfilled. Doppler velocimetry of either the uterine or umbilical vessels, which showed some merit in selecting growth-retarded fetuses at particular risk, has neither become a screening tool for intrauterine growth retardation nor proven clinically successful in improving fetal outcome. Likewise, its use for other complications of pregnancy (eg, postdate pregnancy, twin pregnancy, and diabetes) has not led to improved pregnancy outcome. More recently this technique has been used to study other vascular beds. Changes in the Doppler characteristics of these vascular beds may demonstrate the fetal response to its environment. These investigations provide the potential for a better understanding of fetal physiology; however, it has yet to be shown by prospective evaluation that their application results in improved pregnancy outcome. This review defines the uses and limitations of Doppler ultrasound in current obstetric practice.

A high uterine artery pulsatility index reflects a defective development of placental bed spiral arteries in pregnancies complicated by hypertension and fetal growth retardation

INTRODUCTION

The development of PIH is associated with a defective trophoblast invasion and conversion of spiral arteries into low-resistance uteroplacental arteries. Hypertension may then be a compensatory response to a defective uteroplacental perfusion. Similar mechanisms may operate in IUGR.

AIM

To compare uterine artery Doppler blood flow measurements with placental bed histology. The hypothesis was that placental bed vessel pathology plays a role for a raised flow resistance.

MATERIALS AND METHODS

After blood flow measurements, a placental bed biopsy was taken at CS in 26 complicated (study group) and 29 uncomplicated pregnancies (control group).

RESULTS

The uterine artery PI was significantly more often abnormally high in the study group compared with the control group, and also in hypertensive pregnancies compared with normotensive IUGR pregnancies. Physiological vessel changes were found in all controls but were absent in 76% of study cases. Physiological changes were significantly more often absent in SGA than in AGA newborns. Absence of physiological changes were significantly more often found in cases with an abnormally high PI.

DISCUSSION

The results link together circulatory and structural pathophysiological changes of the uteroplacental unit. A defective physiological conversion of the spiral arteries was associated with an increased uterine flow resistance.

CONCLUSION

This study gave further support for the existence of a triad of defective placental bed vessel maturation, increased uteroplacental flow resistance, and hypertension.

Perinatal mortality in hypertensive disorders of Jewish and Bedouin populations

The aim of this study was to retrospectively compare the perinatal mortality of Jewish and Bedouin hypertensive patients in the Southern area of Israel. Since almost 100% of the deliveries took place in the Soroka Medical Center, the sole hospital of the area, the computerized files of our department during 5 years (1986-1990) were used in the study. Data on the frequency of hypertensive disorder types, rates of stillbirths and neonatal deaths, maternal age and parity, pre-term and term deliveries, prenatal care, intrauterine growth retardation, mode of delivery and fetal sex, were analysed according to ethnicity. Among a total of 40,780 deliveries, 2343 were of hypertensive pregnancies. No difference in the prevalence of hypertensive disorders was found between Jewish and Bedouin women. Perinatal mortality in Jewish hypertensive women was 16.8/1,000 compared with 11.8/1,000 in normotensive, while among the Bedouins the rates were 44.4/1,000 and 22.9/1,000, respectively. In both populations half the rate of perinatal deaths were stillbirths, except among the Jewish hypertensive patients whose fetal deaths reached 72%. Of the risk factors examined the rate of inadequate prenatal care was higher among Bedouins than in Jews. Among women without prenatal care the Jewish hypertensives had a relative risk of 5.29 for perinatal mortality, compared to normotensive pregnant women, whereas in the Bedouins the relative risk was 2.54. Ethnicity was found not to have influence on the prevalence of hypertensive disorders among Jewish and Bedouin pregnant women.(ABSTRACT TRUNCATED AT 250 WORDS)

Diastolic zero-flow in the umbilical artery in twin pregnancies

Clinical arterial blood flow measurements in single pregnancies can not be precisely estimated yet. ARED (absent or reverse end diastolic) flow of the umbilical artery (UA) commonly indicates a symptom of fetal jeopardy. The interpretation of blood flow measurement in twin pregnancies is still controversial. On one hand, no differences in a single pregnancies are found, and on the other hand, increased resistance indices have been reported. In the feto-fetal transfusion syndrome mostly there are normal blood flow measurements. When pathological blood flow occurs, usually it affects the donor. By means of 4 case reports with ARED flow, the value of the investigation method in management of twin pregnancies is demonstrated. Three out of four fetuses with an ARED flow in the UA have died. Case fetus with a normal flow velocimetry survived. Even feto-fetal transfusion syndrome may cause pathological blood flow curves. In fetuses with ARED-flow in the UA fetal hypoxia and acidosis are to be expected. A careful evaluation of the cardiotocogram is indicated with a viable fetus. A possible fetal disturbance may be seen early in blood flow curves and may help provide better obstetrical management.

Thromboxane synthetase inhibition as a new therapy for preeclampsia: animal and human studies minireview

The role of the eicosanoids in the pathophysiology of preeclampsia is reviewed, and the results of animal model and human studies with thromboxane synthetase inhibitors in preeclampsia are described. Potential benefits and limitations of therapy are discussed.

Transvaginal color Doppler in the assessment of the uteroplacental circulation in normal early pregnancy

Transvaginal color Doppler investigation of the uteroplacental circulation was performed on 108 pregnant women with normal intrauterine pregnancy. Decline of resistance index (RI) and pulsatility index (PI) and increase of peak systolic velocity (Ps velocity) were found in all segments of the uteroplacental circulation with advancing gestational age. There was a decrease of RI and PI from the uterine artery through its branches: arcuate, radial and spiral arteries. Ps velocities decreased from the uterine, through the arcuate, to the radial arteries, but Ps velocities in the spiral arteries were higher than those in the radial arteries. According to our results RI seems to be more precise in the assessment of the uteroplacental than the PI.

Transcranial Doppler waveform differences in hyperemic and nonhyperemic patients after severe head injury

Although increased cerebral blood flow velocity is readily measured by transcranial doppler ultrasonography (TCD), the causes of the velocity elevation may differ. After severe head injury, increased blood flow velocity can develop both in patients with global hyperemia (suggestive of vasodilation) and in those without hyperemia (suggestive of vasospasm). The present study attempts to determine whether TCD can differentiate these two mechanisms of velocity increase. Fourteen severely brain-injured patients who developed increased middle cerebral artery blood flow velocity (time-averaged mean velocity > 100 cm/s) were studied. Eight cases were nonhyperemic and six were hyperemic as defined by arterial-jugular venous oxygen content differences of more than 4 mL/dL and less than 4 mL/dL, respectively. The TCD waveform of all eight nonhyperemic cases showed a diastolic notch, which was absent in all six hyperemic patients (p = 0.00066). TCD waveform profile appears to provide a noninvasive means of differentiating at the bedside the two causes of increased flow velocity. If associated with raised intracranial pressure, these require different treatment.

Umbilical and uterine artery flow velocity waveforms in pregnant women with systemic lupus erythematosus treated with aspirin and glucocorticosteroids

Pregnancy in systemic lupus erythematosus (SLE) is at high risk to the mother and fetus. Impaired utero-placental perfusion may increase fetal loss and intrauterine growth retardation. We assessed the changes in impedance to blood flow in the umbilical and uterine arteries in five patients with SLE treated with low dose aspirin and corticosteroids, using Doppler ultrasound longitudinally throughout pregnancy. Blood flow velocity waveforms of the umbilical and uterine arteries were studied by transabdominal and transvaginal Doppler ultrasound, respectively. Resistance index (RI) was measured every two to four weeks from week 10 to term, and the values obtained were compared to those of normal pregnancies. All five patients delivered uneventfully. One neonate was delivered at 36 weeks (2550 g) and one neonate was growth retarded (1900 g at 38 weeks). Three women delivered at 39 weeks (3585 g, 2850 g, and 2800 g). Most umbilical artery RI values obtained throughout pregnancy were above the 95th percentile of normal pregnancies. The highest values of RI of the umbilical artery were assessed in the case of fetal growth retardation. However, most measurements of RI of the uterine artery were under the 95th percentile of normal. The improved pregnancy outcome in patients with SLE treated with aspirin and corticosteroids seems to correlate with their normal uterine artery flow velocity wave forms.

The effect of nifedipine and dipyridamole on the Doppler blood flow waveforms of umbilical and uterine arteries in hypertensive pregnant women

In a study of 45 hypertensive pregnant women, the systolic velocity/diastolic velocity ratio and pulsatility index of the umbilical and uterine arteries showed good correlation with the maternal blood pressure, and they appeared to provide a good parameter for the fetoplacental condition. Using the pulse Doppler method, we studied the effects of the antihypertensive agent nifedipine and of dipyridamole (an agent used to treat proteinuria) on the blood flow of the umbilical and uterine arteries in 16 hypertensive pregnant women. The results proved that both drugs caused a decrease in the vascular resistance of the umbilical artery and suggested that they increased the blood flow volume of this artery and were useful in the treatment of hypertension during pregnancy.

Interrelationship and clinical significance of increased resistance in the uterine arteries in patients with hypertension or preeclampsia or both

OBJECTIVES

This study was designed to evaluate the clinical significance of the Doppler flow velocity waveform analysis of the two uterine arteries on an individual basis and in combination expressed as the mean uterine artery.

STUDY DESIGN

We evaluated uterine artery resistance by means of continuous wave Doppler ultrasonography in 123 pregnant women with chronic hypertension, preeclampsia, or both. The placental location was determined by real-time ultrasonography. Clinical outcomes were compared according to uterine artery abnormalities. The Doppler flow studies were not used in patient management.

RESULTS

In patients with unilateral placentas (n = 67) the placental uterine artery was found to be a better predictor of poor pregnancy outcome than the nonplacental artery and the mean of the two arteries. There was a strong degree of correlation between abnormal nonplacental uterine artery and abnormal mean of uterine artery (r = 0.75, p less than 0.001), and there was a moderate degree of correlation between abnormal placental uterine artery and abnormal mean uterine artery (r = 0.46, p less than 0.001). Uterine artery discordance (left-right uterine artery systolic/diastolic ratio) was mostly the result of an abnormal nonplacental uterine artery (r = 0.74, p less than 0.0001) and not the result of an abnormal mean uterine artery (r = 0.44, p less than 0.003); the degree of discordance did not relate to pregnancy outcome. Unilateral placental location was associated with longer stays in neonatal intensive care units and more perinatal deaths.

CONCLUSION

Because of the differences between the two uterine arteries, we conclude that for proper interpretation of uterine artery flow velocity waveforms, the placental location should be known and each vessel analyzed individually.

Uteroplacental diastolic notching in 510 uneventful pregnancies

In a collective of 510 patients with uneventful pregnancies and deliveries the rate of waveform notching in the uteroplacental flow velocity pattern was examined. Notching appeared to be significantly more frequent in the uterine than arcuate artery. It was unilateral and mainly affected placenta-contralateral sites. Bilateral notching or notching on placental site were the exception. In both flow patterns notching was seen to increase as pregnancy progressed and was slightly higher in the third compared to the second trimester.

The relationship between umbilical artery Doppler velocimetry and fetal biometry

The relationship between peak-systolic/end-diastolic ratio of the umbilical artery waveform and fetal biometry was studied in 127 uncomplicated pregnancies with established dates between 20 and 40 weeks' gestation. At each ultrasonographic examination fetal biometry included measurement of the biparietal diameter, head circumference, abdominal circumference, and femur length. The peak-systolic/end-diastolic ratio was measured by either a continuous or a pulsed-wave method. There were significant linear negative correlations between all the biometric parameters, as well as between the ultrasonographically estimated fetal weight and peak-systolic/end-diastolic ratio. Of the individual ultrasonographic parameters the femur length (for gestations less than 30 weeks) and the abdominal circumference (for gestations greater than or equal to 30 weeks) were found to be best correlated with the peak-systolic/end-diastolic ratio. Regression curves, including the 10th and the 90th percentile, were developed between each biometric parameter (biparietal diameter, head circumference, abdominal circumference, and femur length), as well as between estimated fetal weight and peak-systolic/end-diastolic ratio. The estimated fetal weight nomogram had the best sensitivity (48%) in predicting intrauterine growth retardation. These nomograms should prove most useful in assessing downstream placental vascular resistance in high-risk patients with unknown dates.

Prevention and treatment of pregnancy-associated hypertension: what have we learned in the last 10 years?

High blood pressure (BP) complicates approximately 10% of all pregnancies. Hypertension in pregnancy falls into four categories: (1) preeclampsia-eclampsia, (2) chronic hypertension of whatever cause, (3) preeclampsia-eclampsia superimposed to chronic hypertension or renal disease, and (4) transient or late hypertension (gestational hypertension). Preeclampsia, the association of hypertension, proteinuria, and edema, accounts for more than 50% of all the hypertensive disorders of pregnancy and is a major cause of fetal and maternal morbidity and mortality. Unfortunately, distinguishing between preeclampsia and other causes of hypertension on clinical grounds can be difficult because of the lack of specific tests for differential diagnosis. Increased vascular resistance has been claimed as the primary cause of preeclampsia; however, a variable hemodynamic profile with relatively high cardiac outputs, normal filling pressures, and inappropriately high systemic vascular resistances is now reported by most investigators. Imbalance between vasodilator and vasoconstrictor eicosanoids may account for platelet activation and increased responsiveness to pressor peptides. Altered prostacyclin (PGI2) to thromboxane A2 (TxA2) ratio in maternal uteroplacental vascular bed may favor local platelet activation and vasoconstriction contributing to placental insufficiency and fetal distress. Alternatively, recent evidence seems to suggest that fetal umbilical placental circulation may be the site of the primary vascular injury. Whether low-dose aspirin prevents preeclampsia because it inhibits the excessive maternal TxA2 or whether the partial inhibition of fetal TxA2 is also of therapeutic value remains to be established. Treatment of severe hypertension in pregnancy is probably important to prevent cardiac failure or cerebrovascular accidents in the mother. The need for pharmacological therapy of mild to moderate hypertension is still debated, since no formal studies are available to clarify whether pharmacological treatment in such instances effectively reduces maternal or fetal risk. For the treatment of preeclampsia, hydralazine and nifedipine may be used when delivery is not applicable. Labetalol and diazoxide are effective for hypertensive emergencies. Life-threatening hypertension that does not respond to more conventional therapy is an indication for the use of sodium nitroprusside. For chronic hypertension, alpha-methyldopa remains the treatment of choice; if ineffective, hydralazine or beta-blockers are suitable. Effectiveness and safety of other molecules remain elusive.

Doppler sonographic examinations of uteroplacental, fetoplacental, and fetal hemodynamics and their prognostic value in preterm labor

Doppler examinations of different uteroplacental vessels (uterine arteries, arcuate arteries), umbilical artery, fetal thoracic aorta, and median cerebral artery were performed on 55 patients with idiopathic preterm labor (24.5 to 32.5 weeks). Thirty normal pregnancies of corresponding gestational age served as a control group. Significant differences of median values between the preterm labor and control group were found only for the resistance index (RI) in the central arcuate artery and for the pulsatility index (PI) in the fetal thoracic aorta. In about twenty percent of pregnancies in preterm labor, pathological values of RI and PI in uteroplacental and fetal vessels account for the presence of an impaired perfusion. Elevated PI in the uterine artery placental site and normal RI in the fetal thoracic aorta, correlate significantly to a shorter prolongation of pregnancy, lower gestational age on birth, and lower birth weight. The combination of these two blood flow indices (maternal PI greater than 0.90 and fetal RI less than 0.90) allow us to predict a preterm birth in a high percentage of cases (sensitivity 87.5%, specificity 100%, positive predictive value 100%, negative predictive value 93%).

Adaptive changes in the developing brain during intrauterine stress

Maturation of neurological performance in moderately to severely growth-retarded newborn infants (SGA) can be accelerated by 3 to 4 weeks or more when compared to the development of appropriately grown infants (AGA) of the same gestation. This is particularly the case in multiple pregnancies or pregnancies characterized by maternal hypertension. This clinical finding has been confirmed by neurophysiological studies on the maturation of brainstem auditory evoked responses (BAERs). The possible mechanisms which underly this phenomenon are not yet elucidated. Glucocorticoids, other steroid hormones and catecholamines are elevated in pregnancies with placental dysfunction, and it is known that these substances have multiple actions on neuronal maturation, particularly on mechanisms of release of neurotransmitters. These observations suggest that the acceleration of brain maturation, and lung maturation, in SGA infants reflects an adaptation of the fetus to early extrauterine life. However, if the placental dysfunction progresses, these mechanisms of adaptation will be overwhelmed by severe malnutrition and anoxia which result in cerebral lesions and risk of death. The clinical goal at the present time for obstetric management of these risk pregnancies is to distinguish between these two periods.

Doppler umbilical artery velocimetry in pregnancies complicated by intrahepatic cholestasis

Doppler umbilical velocimetry is a useful clinical tool for antepartum fetal surveillance of pregnancies at risk of fetal compromise. Intrahepatic cholestasis of pregnancy is associated with an increased incidence of fetal death, which might due to the toxic effect of elevated maternal serum concentrations of bile acids. To study a possible effect of the concentration of bile acids on the umbilical circulation we performed pulse-wave Doppler velocimetry of the umbilical artery in 15 patients with intrahepatic cholestasis between 34 and 38 weeks of gestation. The findings were compared to the Doppler flow velocities of the umbilical artery of 129 normal pregnancies. Peak-systolic (A) and end-diastolic (B) velocities of two to three cardiac cycles were measured by electronic calipers and the Pourcelot (PR)-index (PR = (A - B)(A)) was calculated. Two of 29 Doppler measurements in patients with intrahepatic cholestasis were above two standard deviations (2 SD) of the values in normal pregnancies. No significant correlation was found between Doppler flow velocities and serum levels of bile acids (r = 0.20) or the levels of alanine aminotransferase (ALAT) (r = -0.05). The mean level of bile acids was 24 mumol/l with a maximum of 98 mumol/l. The mean level of ALAT was 165 IU/l with a maximum of 576 IU/l. Since even high levels of bile acids do not influence umbilical circulation, Doppler investigations of the umbilical artery seem to be of little value in studying the disease-specific risk of fetal compromise in pregnancies complicated by intrahepatic cholestasis.