Perinatal outcome prediction by maternal homocysteine and uterine artery Doppler velocimetry

OBJECTIVES: (a) To evaluate the predictive value of uterine Doppler velocimetry for pregnancy complications, (b) to study the relationship between abnormal uterine Doppler velocimetry and plasma homocysteine, and (c) to determine whether homocysteine measurement improves the predictive value of uterine Doppler screening. STUDY DESIGN: Prospective study including 94 pregnant women without previous risk factors. Total homocysteine, folate and Vitamin B(12) were analysed. Uterine Doppler velocimetry at weeks 24-25 was performed. RESULTS: The presence of any uterine Doppler alteration had a sensitivity of 66.7%, and a specificity of 81.2%, in predicting obstetric complications. The likelihood ratio was 3.6. The positive and negative predictive values were 27.3 and 95.8%, respectively. The global efficiency was 83.0%. The addition of hyperhomocysteinemia to Doppler alterations increased the sensitivity from 66.7 to 77.8%. CONCLUSIONS: The addition of homocysteine determination to uterine Doppler evaluation in the second trimester does not usefully improve its predictive value.     

Doppler assessment of umbilical artery blood flow for the prediction of outcome in fetal cardiac abnormality

Summary. In a series of 244 pregnancies referred for fetal echocar-diography, the umbilical artery waveform was also studied by pulsed Doppler ultrasound. In 152 normal pregnancies diastolic flow in the umbilical artery was always detectable after 20 weeks gestation. In 4 of 58 normal patients examined before 20 weeks, diastolic flow was absent in some part of the recording. In 34 fetuses with congenital heart disease detected at between 18 and 37 weeks gestation, 10 were found consistently to have associated absent diastolic flow. Five of these fetuses died in utero between 5 and 21 days after the recording; three were aborted and the remaining two died in the neonatal period at 4 and 7 days after the examination. Fetal congenital heart disease with normal umbilical blood flow also had a poor prognosis in general, but the adverse outcome was much less immediate than in fetuses with absent diastolic flow. No correlation was found between the type of congenital heart disease and the characteristics of the umbilical artery waveform. Absent diastolic flow in the umbilical artery indicates a poor short-term prognosis for fetuses with congenital heart disease, particularly after 20 weeks, when fetal death is predictable.     

Doppler assessment of umbilical artery blood flow for the prediction of outcome in fetal cardiac abnormality

In a series of 244 pregnancies referred for fetal echocardiography, the umbilical artery waveform was also studied by pulsed Doppler ultrasound. In 152 normal pregnancies diastolic flow in the umbilical artery was always detectable after 20 weeks gestation. In 4 of 58 normal patients examined before 20 weeks, diastolic flow was absent in some part of the recording. In 34 fetuses with congenital heart disease detected at between 18 and 37 weeks gestation, 10 were found consistently to have associated absent diastolic flow. Five of these fetuses died in utero between 5 and 21 days after the recording; three were aborted and the remaining two died in the neonatal period at 4 and 7 days after the examination. Fetal congenital heart disease with normal umbilical blood flow also had a poor prognosis in general, but the adverse outcome was much less immediate than in fetuses with absent diastolic flow. No correlation was found between the type of congenital heart disease and the characteristics of the umbilical artery waveform. Absent diastolic flow in the umbilical artery indicates a poor short-term prognosis for fetuses with congenital heart disease, particularly after 20 weeks, when fetal death is predictable.     

Study of fetal femoral and umbilical artery blood flow by Doppler ultrasound throughout pregnancy

In order to study the fetal femoral artery resistance index throughout gestation, 221 Doppler examinations of the femoral and umbilical arteries were performed between 13 and 40 weeks gestation. Femoral artery Doppler waveforms showed a pattern of high resistance throughout gestation while the umbilical index decreased progressively. In fetuses with normal growth, high femoral flow resistance indices are physiological.     

The current status of maternal and fetal blood flow velocimetry

Significant progress has been achieved in regard to normative data for uteroplacental and fetal blood flow velocity and the factors which may affect these observations. Associations have been demonstrated between abnormal indices of maternal and fetal blood flow velocity and pregnancy-induced hypertension, fetal growth retardation, fetal blood gas measures, and intrapartum clinical fetal distress. However, in general, the predictive power is modest and no evidence has yet been provided to indicate that these measures can be used as a screening test in the general obstetric population. Continuing research is highly desirable. At the present time, the use of Doppler assessment of blood flow in pregnancy should be limited to the investigational setting.     

Clinical assessment of fetal blood flow velocimetry.

A statistical procedure is presented to analyze the relation between Doppler indices (DIs) such as pulsatility index (PI), resistance index (RI), A/B and clinical data of pregnancy and fetal outcome of three groups: (1) uncomplicated pregnancy, eutrophic fetus (NF), (2) pregnancy-induced hypertension (PIH), and (3) pregnancy and delivery of a dystrophic fetus (IUGR), and the acidity classes according to Saling, respectively. Proceeding and mathematical requirements as well as the possibilities to validate the methodology are introduced, and an application to previously published data is presented. By multivariate analysis of the data a fair prognosis of NF, PIH and IUGR was possible. The variability inherent to the data sampling requires a mathematical postprocessing in the framework of an adequate model before any clinical conclusions can be derived from DIs.     

Maternal uterine artery Doppler flow velocimetry and the risk of stillbirth

OBJECTIVE: We sought to relate the risk of antepartum stillbirth to uterine artery Doppler flow velocimetry at 22-24 weeks. METHODS: Data were available from 30,519 unselected women from seven units in the UK who had uterine artery Doppler performed between 22 and 24 weeks of gestation. The risk of stillbirth (n=109) was assessed using time to event and logistic regression analysis. Stillbirths were subdivided into placental (due to abruption, preeclampsia, or growth restriction) or unexplained. RESULTS: The risk of placental stillbirth was increased among women with a mean pulsatility index in the top decile (adjusted hazard ratio [HR] 5.5, 95% confidence interval [CI] 2.8-10.6) and those with a bilateral notch (adjusted HR 3.9, 95% CI 2.0-7.8). The relationship between a mean pulsatility index in the top decile and the risk of unexplained stillbirth was weaker (adjusted HR 2.5, 95% CI 1.1-5.6) and there was no association with a bilateral notch. Placental stillbirths occurred at earlier gestations than unexplained stillbirths (median [interquartile range] 30 [26-36] compared with 38 [36-40], P<.001). Consequently, being in the top 5% of predicted risk of stillbirth on the basis of the combination of mean pulsatility index and notching was a good predictor (sensitivity, specificity, and positive likelihood ratio) of all cause stillbirth up to 32 weeks (58%, 95%, and 12.1, respectively) but a poor predictor of stillbirth at later gestations (7%, 95%, and 1.3, respectively). CONCLUSION: Abnormal uterine artery Doppler was a better predictor of the risk of stillbirth due to placental causes than unexplained stillbirth. Consequently, abnormal uterine artery Doppler was a good predictor of stillbirth at extreme preterm gestations but a poor predictor of stillbirth at term. LEVEL OF EVIDENCE: II.     

The effect of epidural anaesthesia for caesarean section on maternal uterine and fetal umbilical artery blood flow velocity waveforms

Summary. The blood flow resistance in the maternal uteroplacental and fetal umbilical artery circulation was studied in eight otherwise normal patients undergoing elective lower segment caesarean section. The systolic/diastolic A/B ratio (the ratio of peak systolic to least diastolic flow velocity) for the uteroplacental and fetal umbilical circulation was determined from the artery blood flow velocity-time waveform and used as an index of blood flow resistance. Each patient received a 1 litre intravenous crystalloid infusion before an epidural bupivicaine injection. Both crystalloid infusion and epidural anaesthesia resulted in a significant decrease in the maternal uteroplacental systolic/diastolic (A/B) ratios, associated with a decrease in fetal umbilical artery A/B ratio. This study suggests a beneficial fetal effect from the improved maternal uterine perfusion after epidural anaesthesia.     

The effect of epidural anaesthesia for caesarean section on maternal uterine and fetal umbilical artery blood flow velocity waveforms

The blood flow resistance in the maternal uteroplacental and fetal umbilical artery circulation was studied in eight otherwise normal patients undergoing elective lower segment caesarean section. The systolic/diastolic A/B ratio (the ratio of peak systolic to least diastolic flow velocity) for the uteroplacental and fetal umbilical circulation was determined from the artery blood flow velocity-time waveform and used as an index of blood flow resistance. Each patient received a 1 litre intravenous crystalloid infusion before an epidural bupivicaine injection. Both crystalloid infusion and epidural anaesthesia resulted in a significant decrease in the maternal uteroplacental systolic/diastolic (A/B) ratios, associated with a decrease in fetal umbilical artery A/B ratio. This study suggests a beneficial fetal effect from the improved maternal uterine perfusion after epidural anaesthesia.     

Doppler measurements of maternal and fetal blood flow

Data accumulated over the last decade suggest that Doppler flow velocity waveforms can be used to study both maternal and fetal circulation. Information obtained with this technique appears useful as a screen for both maternal and fetal risk, as an aid to understanding perinatal anatomy and physiology, and as an adjunct to standard means of fetal surveillance.     

Maternal and fetal plasma endothelin levels in intrauterine growth restriction: relation to umbilical artery Doppler flow velocimetry

The objective of this study was to examine maternal and fetal endothelin-1 (ET-1) in pregnancies complicated with intrauterine growth restriction (IUGR) and to correlate these data with umbilical artery Doppler flow velocity waveforms (FVW). Higher mean maternal (13.8 +/- 6.4 vs 9.2 +/- 3.4 pmol/L, p < 0.05) and fetal (18.5 +/- 9.6 vs 11.7 +/- 6.9 pmol/L, p < 0.05) ET-1 levels were found in pregnancies complicated with IUGR than in controls. Fetal ET-1 level was related to birth weight percentile for gestational week. Maternal and fetal ET-1 concentrations were not related to umbilical artery Doppler flow S/D ratio, PI and RI. Maternal or fetal ET-1 concentrations were also not related to umbilical artery pH, PO2 and PCO2. Pregnancy-induced hypertension was significantly associated with an elevated fetal and maternal ET-1 concentration. In conclusion, increased production and secretion of ET-1 may play a role in the pathophysiology of idiopathic IUGR. Over-production of ET-1 in IUGR is not associated with increased placental resistance as reflected in abnormal umbilical artery Doppler FVW.     

Evaluation of fetal right coronary artery blood flow velocimetry

OBJECTIVES: In the present study fetal right coronary artery blood flow velocimetry was assessed. DESIGN: The prognostic value of the fetal right coronary artery blood flow velocimetry was evaluated in relationship with parameters of newborn's condition after birth. MATERIAL AND METHODS: The study was performed in 102 cases of pregnancies complicated by pregnancy induced hypertension. Blood flow velocimetry was visualized from fetal right coronary artery and correlated with perinatal outcome parameters. RESULTS: Fetal coronary blood flow velocimetry was visualized only in 11 cases. Coronary blood flow velocimetry visualisation correlated with each parameter of after-birth evaluation. The method has the highest specificity (97.7%) and positive prognostic value (85%) concerning evaluation of newborn's condition. CONCLUSIONS: Fetal right coronary artery blood flow velocimetry visualisation is a late sign of chronic fetal hypoxia. This seems to be a factor which causes maximal coronary vessels dilatation and allows oxygenation of fetal heart muscle.     

Measurement of blood flow in maternal pelvic artery and umbilical cord artery with the ultrasonic pulsed Doppler flow method

The maternal pelvic artery was detected with the B-mode, and volume of flow through it measured with the pulsed ultrasound Doppler device in the supine and left recumbent positions. The blood flow state and vascular resistance of the maternal pelvic artery and of the umbilical cord artery were investigated in gestosis and normal pregnancy. The volume of blood flow through the right maternal pelvic artery showed a tendency to increase after the posture was changed to the left recumbent position. The peak frequency (Fp) showed a tendency to increase in gestosis, particularly in the edema group. The spectral width (SWp)/Fp value showed a tendency to be lower in the edema group than in normal subjects, and showed a higher value in hypertension accompanied by proteinuria than in normal subjects. As an indication of peripheral vascular resistance, the pulsatility index (PI) in the maternal pelvic artery was determined, and resistance index (RI) in the umbilical cord artery was also determined. The PI showed a tendency to increase more in gestosis than in normal subjects, particularly in hypertension accompanied by proteinuria. The RI was higher in maternal hypertension accompanied by proteinuria than in normal pregnancy. The hematocrit and fibrinogen vales were slightly higher, though insignificantly, in gestosis than in normal subjects.     

The relationship between fetal biophysical assessment, umbilical artery velocimetry, and fetal acidosis

In a prospective study of 62 patients undergoing cesarean delivery before the onset of labor, fetal biophysical assessment and umbilical artery systolic-diastolic ratios (S/Ds) were performed within 3 hours of delivery. There was a significant relationship between the fetal biophysical profile score and cord arterial as well as cord venous pH. However, there was no identifiable relationship between S/D and cord arterial or venous pH. The efficacies of the biophysical components alone (nonstress test [NST] and fetal biophysical profile) and in combination with S/D to predict fetal acidosis were determined. The NST had the best sensitivity (100%) and negative predictive value (100%). The fetal biophysical profile had the best specificity (91%), positive predictive value (62%), and overall efficiency (90%). The S/D had the lowest sensitivity (66%), specificity (42%), positive predictive value (16%), negative predictive value (88%), and overall efficiency (45%). The addition of S/D to the NST or fetal biophysical profile did not improve diagnostic accuracy. These data suggest that the NST should be used as a primary test for the antepartum detection of fetal acidosis, whereas the fetal biophysical profile is a reasonable adjunct test. The umbilical artery S/D, as determined by continuous-wave Doppler velocimetry, has no value as a primary method or an adjunct in the antepartum detection of fetal acidosis.     

Doppler umbilical artery velocimetry in fetuses with polyhydramnios

Polyhydramnios is a condition of multiple etiologies, many of a benign nature, but some of which are incompatible with life. To evaluate Doppler velocimetry results as a prognostic parameter in these fetuses, we reviewed all of our cases of polyhydramnios that underwent Doppler analysis in the third trimester. Fifty-four fetuses were studied. Eleven (20.4%) had abnormal waveforms and 43 (79.6%) had normal waveforms. An abnormal waveform was associated with a significantly higher incidence of congenital anomalies, perinatal mortality and intrauterine growth retardation. Six of the 11 fetuses had abnormal karyotypes. Macrosomia was present in 37.2% of fetuses with normal waveforms and in no fetus with an abnormal waveform. Doppler analysis may aid in the counseling and management of patients with polyhydramnios. In cases with an abnormal ratio, the physician and patients should be prepared for a poor outcome and third trimester genetic analysis should be strongly considered.     

Maternal glycemic control and umbilical artery Doppler velocimetry

Objective: To determine whether information from umbilical artery Doppler flow velocity waveforms significantly improves the prediction of adverse perinatal outcome, independently of maternal glycemic control, in pregnancies complicated by diabetes. Study design: The medical records of 277 pregnant women with diabetes were reviewed. Glycemic control was determined by glycosylated hemoglobin concentration and umbilical artery Doppler velocimetry by using systolic/diastolic ratios (S : D), both obtained during the third trimester. Pregnancies with adverse perinatal outcome were compared to those with good outcome. Logistic regression analysis was used to adjust for glycemic control, and to test whether an elevated umbilical artery Doppler S : D ratio was independently associated with pregnancy outcome. Results: Adverse pregnancy outcome occurred in 51.6% of these pregnancies (143/277). The mean third-trimester glycosylated hemoglobin (7.7 ± 1.9% vs. 6.7 ± 1.3%, p < 0.001) and the umbilical artery S : D ratio were significantly higher (2.6 ± 0.6 vs. 2.4 ± 0.3, p < 0.001) in the pregnancies with adverse outcome. Logistic regression analysis showed that umbilical artery S : D ratio was an independent predictor of adverse perinatal outcome after adjusting for the third-trimester glycosylated hemoglobin level. Forty per cent of patients with normal Doppler findings (S : D ratio of < 3.0) and normal glycemic control values (glycosylated hemoglobin level of < 7.5%) had an adverse pregnancy outcome. Sixty-three per cent of patients with an abnormal result for one of these tests had an adverse pregnancy outcome. Ninety-six per cent of patients with both abnormal Doppler findings and abnormal glycemic control had an adverse pregnancy outcome. Conclusion: Umbilical artery Doppler velocimetry improves the predictive value for adverse perinatal outcome, independently of glycemic control, in pregnancies complicated by diabetes. The combination of an abnormal umbilical artery S : D ratio and abnormal glycosylated hemoglobin was strongly associated with adverse pregnancy outcome.