Elevated umbilical artery systolic/diastolic ratio in the absence of fetal growth restriction

Purpose

To evaluate whether patients with isolated elevation of umbilical artery (UA) systolic/diastolic (S/D) ratio are at increased risk for adverse perinatal outcome.

Methods

This is a retrospective cohort study of 330 patients who underwent routine evaluation at our maternal fetal medicine center. We regularly perform UA S/D ratio analysis with every third trimester sonogram. All identified patients were included and divided into four groups based on estimated fetal weight (EFW) and UA S/D ratio. Perinatal outcome was compared between the groups.

Results

Regardless of the EFW, fetuses with persistent elevated UA S/D ratio showed significantly more preterm deliveries (p < .001), neonatal intensive care unit (NICU) admissions (p < .001), longer stay in the NICU (p < .001) and lower birth weight (p < .001) relative to controls. Stepwise logistic regression analysis demonstrated that being a member in any study group significantly and independently predicted birth weight less than the 10th percentile and preterm delivery. Patients with persistently elevated S/D ratio were significantly and independently from other factors, more likely to have a newborn admitted to the NICU.

Conclusion

Our results indicate a suboptimal perinatal outcome in all pregnancies with an elevated UA S/D ratio. These fetuses may benefit from intensive monitoring.     

Does the umbilical artery systolic/diastolic ratio reflect flow or acidosis? An umbilical artery Doppler study of fetal sheep

We studied four fetal sheep at 114 to 139 days' gestation to evaluate the effect of acute placental embolization on placental perfusion, fetal oxygenation and acid-base status, and the umbilical artery systolic/diastolic ratio. Studies were performed after maternal anesthesia was induced in an acute model, with serial umbilical artery embolizations performed at 20 to 30 minute intervals. Fetal umbilical flow, systolic/diastolic ratio, and arterial blood gas levels were followed up. One animal maintained a normal systolic/diastolic ratio despite a 50% drop in flow after the first injection and pH of 6.91, and died after the second injection. The remaining three animals showed significantly decreased flow after the third injection (p less than 0.02), with no change in the systolic/diastolic ratio. The systolic/diastolic ratio increased significantly after the fourth injection (p less than 0.05) when flow had dropped even further. Corresponding decreases in PO2 and pH did not achieve statistical significance. The magnitude of all changes increased with subsequent embolizations. We conclude that in this model significant reductions in flow result in small increases in the systolic/diastolic ratio and that greater magnitude changes in the systolic/diastolic ratio appear only with severely diminished flow and PO2, when acidosis develops.     

Catecholamine levels and their correlation to blood gases in umbilical venous blood obtained by cordocentesis

The plasma catecholamine concentration was evaluated in umbilical venous blood obtained by cordocentesis performed in 77 fetuses for indications including: nonimmune hydrops; Rh incompatibility; intrauterine growth retardation; polyhydramnios; anomalies; immunological disorders, and possible viral infection. The pH as well as pO2 of the umbilical venous blood showed a notably significant negative correlation with the norepinephrine concentration (r = -0.5607, r = 0.4467); while pCO2 was also significantly correlated with the norepinephrine concentration (r = 0.4955). When the pCO2/pO2 ratio was tentatively put up for comparison, the ratio was undoubtedly better correlated (r = 0.60442) with the fetal norepinephrine concentration than any other biochemical variable. Moreover, the ratio over 2.0 suggests that fetal catecholamine values have reached abnormal levels.     

Biophysical profile and its relation to fetal blood gas level obtained by cordocentesis

Biophysical profile (BPP) score was assessed immediately before fetal blood sampling by cordocentesis in 150 fetuses referred to our hospital, 95 after and 55 before 30 weeks of gestation. In 95 fetuses after 30 weeks of gestation, 39 fetuses were evaluated with BPP scores of 12, 35 were from 8 to 11 and 21 were less than 7. In 55 fetuses before 30 weeks of gestation, 8 fetuses were evaluated with BPP scores of 12, 27 were from 8 to 11 and 20 were less than 7. pO2, pH and pCO2 in fetuses with a score less than 7, either before or after 30 weeks of gestation, (with a score less than 7) did not significantly differ, in comparison to the other two groups. No variables in the biophysical profile precisely reflect fetal hypoxemia, acidemia or hypercarbia. Since even the fetus with a BPP score of greater than 8 may not always be assured of well-being and not all fetuses with a score of less than 7 are necessarily in a deteriorated condition, it is necessary to evaluate fetal condition on the basis of fetal blood gas data obtained by cordocentesis, especially when the fetus is additionally handicapped by prematurity or morbidities such as growth-retardation.     

Pulsed Doppler umbilical artery waveforms: significance of elevated umbilical artery systolic/diastolic ratios in the normally grown fetus

Previous studies have demonstrated a high correlation between elevated resistance in the placental circulation, evidenced by abnormal umbilical artery systolic-to-diastolic (S/D) ratios, and the subsequent birth of a small for gestational age (SGA) infant. However, few data exist on the significance of elevated S/D ratios for pregnancies in which outcome does not involve an SGA infant. Pulsed Doppler spectral recordings and level II ultrasound examinations were performed 373 times in 256 referred high-risk patients. Doppler data were not used for patient management decisions. Thirty-two women with elevated umbilical artery S/D ratios of 4.5 or greater (defined as abnormal regardless of gestational age) gave birth to non-SGA infants. The ultrasound characteristics and outcome for this group were compared with those of 200 patients who were also non-SGA but who exhibited normal waveforms and with 24 SGA infants with predominantly abnormal waveforms. Thirty-one percent of the non-SGA infants with abnormal waveforms had structural malformations, a rate significantly higher (P less than or equal to .03) than the 18% malformation rate in the normal-waveform group. Further, the stillbirth rate and number of terminations of pregnancy for lethal anomalies were five times greater in the non-SGA group with abnormal waveforms than in the non-SGA group with normal waveforms (P less than or equal to .001). A wide variety of structural malformations was observed in the abnormal-waveform group, most frequently involving the central nervous system. Amniotic fluid volume tended to be decreased in the SGA group, whereas increased amniotic fluid volume or hydramnios was seen in 23% of the non-SGA abnormal-waveform group.     

脐带螺旋指数与脐动脉血流S/D比值及妊娠结局关系的研究

目的:探讨脐带螺旋指数(umbilical coiling index,UCI)与脐动脉血流收缩期最大血流速度(S)/舒张期末血流速度(D)比值(S/D比值)及妊娠结局之间的关系。方法:选择在我院住院分娩妊娠37~40周的孕产妇720例,计算UCI值,分析UCI与脐动脉血流S/D比值及胎儿窘迫、新生儿体重、新生儿窒息、围产儿死亡、羊水指数、产后出血及剖宫产率之间的关系。结果:UCI正常组与UCI不足组之间脐动脉血流S/D比值及羊水指数、产后出血、剖宫产率无显著差异,UCI不足组胎儿窘迫、新生儿窒息、围产儿死亡发生率显著高于UCI正常组。UCI过高组的脐动脉血流S/D比值、羊水过少发生率及剖宫产率明显高于UCI不足组,两组间胎儿窘迫、新生儿窒息、围产儿死亡发生率无显著差异。UCI过高组脐动脉血流S/D比值、胎儿窘迫、新生儿窒息、围产儿死亡、羊水过少发生率及剖宫产率明显高于UCI正常组,两组差异有统计学意义。结论:UCI异常可能与脐动脉血流S/D比值及妊娠结局相关。     

Doppler measurements of fetal and uteroplacental circulations: relationship with umbilical venous blood gases measured at cordocentesis

A pulsed Doppler study of the fetal and uteroplacental circulations was performed on 41 pregnant women with small-for-gestational-age and 10 women with appropriate-for-gestational-age fetuses at 19 to 37 weeks' gestation. Blood gases and pH, measured in umbilical venous samples obtained by cordocentesis within 1 hour of the Doppler studies, were correlated individually and as an "asphyxia" index, to the Doppler and ultrasonographic biometric measurements. Although there were significant correlations between the majority of the ultrasonographic biometric and Doppler measurements with the blood gas results, better correlations were found with the ratio of common carotid artery to descending thoracic aorta mean velocity and pulsatility index. The best predictor of asphyxia was an index comprising aortic mean velocity and the common carotid artery pulsatility index. When this index was abnormal, 89% of fetuses had an asphyxia index 1 SD above the mean and 60% 2 SDs above the mean. A normal index was always associated with normal blood gases. The indices representing the inverse relationship of impedance and velocity in the two major vessels that supply the brain and the abdominal viscera provide the best prediction of the fetal condition because they reflect the hemodynamic response to changes in the partial pressure of respiratory gases.     

肝素改善妊娠中晚期脐动脉血流异常的临床效果

目的评价肝素对改善妊娠中晚期脐动脉收缩期最大血流速度(S)与舒张末期血流速度(D)的比值异常的临床效果。方法将脐动脉血流S/D比值大于相应孕周的第95百分位以上的67例妊娠中晚期妇女共72例胎儿(5例双胎)分为研究组35例孕妇(38例胎儿),对照组32例孕妇(34例胎儿),知情同意后,研究组用肝素6250U或12500U+5%葡萄糖500ml、静脉滴注,4~6h内滴完,每天1次,平均治疗(37±21)d,范围1~10d;对照组应用低分子右旋糖酐500ml,丹参30ml+10%葡萄糖500ml,东莨菪碱20mg+10%葡萄糖500ml,静脉滴注,每天1次,平均治疗(67±28)d,范围3~14d。定期复查脐动脉血流S/D比值(3~5d1次,严重者每天1次)。结果研究组平均每天脐动脉血流S/D比值下降037,对照组平均每天脐动脉血流S/D比值下降014,两组研究结果比较,差异有统计学意义(P<005)。研究组所需治疗时间显著短于对照组,两组比较,差异也有统计学意义(P<001)。对照组中有10例胎儿脐动脉血流S/D比值进行性升高,2例胎儿脐动脉血流S/D比值出现无穷大,即舒张末期缺如而致胎儿死亡。结论肝素治疗妊娠中晚期脐动脉血流S/D比值异常升高,效果显著,疗程更短。     

The diagnostic efficacy of the umbilical arterial systolic/diastolic ratio as a screening tool: a prospective blinded study

This prospective blinded study investigated the diagnostic efficacy of the umbilical arterial systolic/diastolic ratio performed at 34 to 36 weeks' gestation for identifying pregnancies at a high risk for adverse perinatal outcomes. A series of 350 consecutive singleton pregnancies were included in the study. A continuous-wave Doppler instrument with a 4 MHz transducer was used. The criteria for an abnormal perinatal outcome included intrauterine growth retardation, an Apgar score of less than 7 at 5 minutes, umbilical arterial pH at birth less than 7.20, presence of thick meconium, fetal distress in labor, and neonatal complications necessitating admission to the neonatal intensive care nursery. The analytic techniques included determination of the receiver operating characteristic curve, sensitivity, specificity, positive and negative predictive values, and the kappa index. The results demonstrated that although the cutoff value of 2.9 showed the maximum inherent discriminatory power, its diagnostic efficacy (sensitivity, 0.83; specificity, 0.87 positive predictive value, 0.74; negative predictive value, 0.92; and kappa index, 0.68) was not substantially different from that of the more common cutoff value of 3.0 (sensitivity, 0.79; specificity, 0.93; positive predictive value, 0.83; negative predictive value, 0.91; and kappa index, 0.73). Both values were rated good to excellent by the kappa index. The study also demonstrated that the systolic/diastolic ratio was a better predictor of general abnormal outcome than of the suboptimal fetal growth.     

Comparison of the modified biophysical profile to a “new” biophysical profile incorporating the middle cerebral artery to umbilical artery velocity flow systolic/diastolic ratio

OBJECTIVES: The objective of this study was to determine whether the addition of the middle cerebral to umbilical artery systolic/diastolic velocity waveform ratio to the modified biophysical profile would improve perinatal outcome in patients at high risk. STUDY DESIGN: A prospective, randomized outcome study of patients referred to the perinatal laboratory for antenatal surveillance was undertaken. Six hundred sixty-five patients were randomized to two antenatal surveillance protocols: group 1, modified biophysical profile; and group 2, modified biophysical profile plus evaluation of the middle cerebral artery to umbilical artery systolic/diastolic ratio. Patients were followed up serially and neonatal outcome data including gestational age at delivery, birth weight, incidence of cesarean section delivery for fetal distress, admission to the neonatal intensive care unit, days in the neonatal intensive care unit, and the presence of significant neonatal morbidity were tabulated. RESULTS: The total population showed no statistical difference in outcome parameters between groups 1 and 2. However, a subgroup of patients evaluated for suspected uteroplacental insufficiency did show a significant reduction in caesarean section for fetal distress in group 2 patients. CONCLUSIONS: In a subgroup of patients at risk for uteroplacental insufficiency, the addition of the middle cerebral/umbilical artery ratio to an antenatal surveillance protocol should be expected to improve perinatal outcome. (Am J Obstet Gynecol 1998;178:1346-53.)     

Safety of fetal blood sampling by cordocentesis in fetuses with single umbilical arteries

OBJECTIVES: To examine the safety of cordocentesis in fetuses with single umbilical arteries. METHODS: Retrospective analysis of all cases of cordocenteses in fetuses with single umbilical arteries over a five-year period at one centre. We analysed the records for pregnancy details, outcomes, and procedure-related complications, and compared these to similar data for cordocenteses procedures performed, during the same period, for similar indications in fetuses with three-vessel cords. RESULTS: Twenty-nine eligible cases were identified. All procedures were performed for the indication of fetal structural abnormalities, and seven fetuses (24%) had abnormal karyotypes. The median gestational age at the time of the procedure was 21 weeks (range 19-34 weeks). There were no procedure-related fetal losses but the umbilical artery was inadvertently punctured in one case, resulting in prolonged bradycardia with spontaneous recovery. These outcomes compare favourably to those of a total of 134 cordocenteses procedures in fetuses with three-vessel cords. CONCLUSION: Cordocentesis in cases with single umbilical arteries does not appear to carry more risk than in cases with three-vessel cord, and should continue to be performed by adequately trained specialists when indicated. Extra care should be undertaken to avoid puncturing the umbilical artery.     

Antepartum heart rate patterns in small-for-gestational-age third-trimester fetuses: correlations with blood gas values obtained at cordocentesis

Antepartum fetal heart rate records were made immediately before cordocentesis and blood gas analysis in 58 small- and 29 appropriate-for-gestational-age fetuses at 27 to 38 weeks' gestation. All appropriate-for-gestational-age fetuses had blood PO2 and pH values within the normal ranges for gestation, and in 27 of 29 cases the heart rate pattern was reactive; in two it was nonreactive. Abnormal heart rate patterns were present in 15 of the 19 small-for-gestational-age fetuses that were found to be hypoxemic, acidemic, or both. The abnormalities included decreased baseline variation, absence of accelerations, presence of decelerations, and increased baseline heart rate. A repetitive decelerative pattern best identified the hypoxemic fetuses. Fetal PO2 values in the lower normal range, present in many of the small-for-gestational-age fetuses, were in general associated with a reactive fetal heart rate pattern.     

Divergent systolic diastolic ratio of the uterine arteries and its significance

Objectives

To determine whether difference in the S/D ratio of both sides of uterine arteries was significantly associated with the development of IUGR

Methods

One hundred and ten women attending the antenatal clinic of our hospital were included in the study. At the time of anomaly scan at 20 weeks doppler assessment of both uterine arteries was done. Systolic diastolic ratio of both sides was calculated. Clinical outcome was recorded at the time of birth. Statistical analysis was performed using chi-square test, regression curve, and Fischer test, using SPSS software.

Results

The correlation coefficient between the average S/D ratio and the difference between the right and left s/d ratio (δ) was 0.67 which was highly significant (p<.001). Abnormal S/D ratio difference defined as more than 1 was significantly associated with IUGR. (p<.001). The placenta on histopathology examination showed significantly lesser number of vessels per tertiary villus in those with abnormal S/D ratio difference (p=.045).

Conclusion

Abnormal S/D ratio difference in uterine arteries is a significant pathophysiological event which results in decreased placental perfusion and it appears that it is the resultant placental ischemia which is responsible for intrauterine growth retardation and low birth weight at delivery.     

The correlation between renal function and systolic or diastolic blood pressure in severe preeclamptic women.

OBJECTIVE: To evaluate the correlation between renal function and systolic or diastolic blood pressure in preeclamptic mothers. METHODS: In this prospective study from August 1998 to September 2002, 28 women >or= 28 weeks gestation with severe preeclampsia were selected. Meanwhile, 56 normotensive pregnant women without proteinuria or edema served as the control group. Urine was collected for 24 hours for all subjects. The concentration of uric acid, blood urea nitrogen, creatinine, sodium, calcium, and albumin in the 24-hour urine and blood of both groups were examined. Neonatal outcome also was evaluated. RESULTS:The serum and 24-hour urine concentration of blood urea nitrogen, creatinine, and albumin were significantly higher in severe preeclamptic women. Serum uric acid and urinary albumin/creatinine ratio was significantly higher in severe preeclamptic women compared with that in normotensive mothers and showed positive correlation with systolic or diastolic blood pressure. On the other hand, serum calcium/creatinine ratio was significantly lower in the severe preeclamptic group and negatively correlated to blood pressure. In multiple regressions, systolic or diastolic blood pressure was dependent on serum uric acid, albumin/creatinine, and calcium/creatinine ratios. Fetal birth weight was significantly lower in women with severe preeclampsia and with a lower Apgar score < 7 at 1 minute and 5 minutes and more preterm delivery compared with that in normotensive women. CONCLUSION: Renal function in women with severe preeclampsia was significantly impaired and highly correlated with systolic or diastolic blood pressure.     

Uterine artery Doppler velocimetry: the significance of divergent systolic/diastolic ratios

Continuous wave Doppler studies were carried out on both uterine arteries in 71 pregnant women from the twentieth week of gestation onward. Analysis of the waveform included the systolic/diastolic ratio and the presence or absence of a diastolic notch. In the current study, these ratios from 31 women with left/right systolic/diastolic difference, (between left and right uterine arteries) were compared with those of women having normal ratios. A normal left/right systolic/diastolic ratio difference of 0.3 with SD of 0.3 was found. When the left/right difference was plotted against the left/right averaged systolic/diastolic ratio, a correlation coefficient of 0.7 was noted (p less than 0.001). Significant outcome differences were noted between normal and abnormal left/right difference systolic/diastolic ratios in the perinatal parameters of gestational age at delivery, fetal weight, pregnancy-induced hypertension, proteinuria, and intrauterine growth retardation. Divergent uterine artery ratio findings are a result of one artery being the dominant supplier to the placenta. The majority of women with an elevated systolic/diastolic ratio seem to have divergent uterine blood supply to the uterus and placenta. These data suggest that errors in placentation site contribute to the development of preeclampsia and growth retardation in the fetus.     

分娩时脐动脉血气分析的临床意义

目的了解分娩时脐动脉血气的临床意义。方法选取2005年3月至2006年12月在北京大学第一医院分娩的产妇810例,临床诊断胎儿窘迫401例,无胎儿窘迫409例,在胎儿娩出后立即行脐动脉血气分析,并追踪新生儿结局,进行分析。结果①胎儿窘迫组中脐血pH值〈7.2者49例,占12.2%,而无胎儿窘迫组pH值〈7.2者26例,占6.4%。二者间差异有统计学意义（P=0.004）;胎儿窘迫组脐血pH均值（7.25±0.24）,无胎儿窘迫组脐血pH均值（7.28±0.05）,两组差异有统计学意义（P=0.023）;②新生儿出生后1min Apgar评分〉7分者中脐血pH值〈7.2占8.3%,而Apgar评分≤7分者中高达34.5%,二者差异有统计学意义（P=0.000）;③本研究中新生儿缺氧缺血性脑病（HIE）共18例,Apgar评分≤7分对HIE诊断的敏感性为38.9%,特异性为97.2%,阳性预测值24.1%,阴性预测值98.6%;脐血pH值〈7.2对HIE诊断的敏感性55.6%,特异性91.8%,阳性预测值13.3%,阴性预测值98.9%;Apgar评分≤7分和pH值〈7.2联合预测HIE的发生,特异性能增加至99.4%,阳性预测值增加至50%,阴性预测值98.4%。结论临床诊断胎儿窘迫者大多数出生时脐血气正常,可能存在过度诊断和治疗现象;血气分析是Apgar评分的补充,二者结合能增加对HIE诊断的特异性和阳性预测值,应结合Apgar评分和脐动脉血气分析来共同评价新生儿预后。     

Changes in intracardiac Doppler blood flow velocities in fetuses with absent umbilical artery diastolic flow

Umbilical artery Doppler blood flow velocity studies were used to identify 14 fetuses with absent flow during diastole to determine the significance of absent umbilical artery diastolic flow. Outcomes of these fetuses were recorded, and the associated intracardiac Doppler changes were identified in 12 of them. Maximal and mean intracardiac flow velocities were measured, and volume flows through the right (tricuspid valve, pulmonary valve) and left (mitral valve, aortic valve) sides of the heart were compared. Ratios of intracardiac peak flow velocity in late diastole to peak flow velocity in early diastole were calculated. Eleven fetuses had intrauterine growth retardation, and four had multiple congenital anomalies. Fetuses with no diastolic flow in the umbilical artery had increased volume flow across the tricuspid and pulmonary valves compared with normal fetuses of similar weights. The ratio of right-sided to left-sided volume flow in the heart (2.15:1) was increased compared with values in normal fetuses (1.33:1, p less than 0.01). The ratio of late diastolic to early diastolic peak flow velocities across the mitral valve was decreased (p less than 0.01). Absent umbilical artery diastolic flow is associated with increased tricuspid and pulmonary valve volume flow and changes in mitral flow velocity patterns, which suggests that there are alterations in left ventricular function.     

胎儿电子监护和脐血流与胎儿窘迫的关系

目的探讨胎儿电子监护和脐血流指标与胎儿缺氧和酸中毒的关系.方法妊娠晚期孕妇547例,分娩前1周内检测脐血流,记录S/D比值(收缩期末 最大的血流速度/舒张期末最大的血流速度),临产前1天或临产后行胎心监护.分娩后记录 新生儿Apgar评分,抽取脐带动脉血作血气分析,测定乳酸和超氧化物歧化酶(SOD)值.[ HTH〗结果 547例产妇均行血气分析, 407例检测乳酸和SOD值,285例检测脐血流 ;239例行产前胎心监护, 317例行产时胎心监护.经阴道分娩组NST无反应者的pH明显升高 (P《0.01),PCO2和乳酸明显降低(P《0.05);剖宫产组NST有反应与NST 无反应之间的HCO3-、TCO2有显著差异(P《0.05).产时监护阴性与阳性者的PO 2、HCO3-、TCO2、ABE和乳酸均有显著差异(P《0.05).S/D比值与P O2密切相关(P《0.01).S/D《2.6者和S/D≥2.6者两组其SOD值有显著差异(P 《0.05).Apgar评分》7分和Apgar评分≤7分两组其HCO3-、TCO2、ABE ( P《0.01),pH、PCO2、乳酸均有显著差异(P《0.05).结论 在临产前胎心监护发现胎动减少或无胎心加速时,提示胎儿缺氧存在,发展为代谢性酸中毒 尚需一定时间,如及时终止妊娠则不发展为酸中毒;临产后OCT或CST出现重度变异减速或晚 期减速提示缺氧酸中毒的存在.S/D比值以2.6为标准能预测子宫胎盘血流动力学改变,提示胎儿慢性缺氧.