Ultrasound measurement of fetal blood flow in predicting fetal outcome

Health care consumption among adolescent girls prior to diagnoses of sexual abuse, a case-control study in the Stockholm Region

Victims of sexual abuse have more co-morbidities than other persons in the same age and the most affected group are adolescent girls. Little is known about how this is reflected in health care consumption patterns prior to the registered diagnosis. The aim of this investigation was to study health care consumption patterns among girls, 12-17 years old, 1 and 2 years prior to their diagnoses of sexual abuse. Through the Stockholm Region administrative database (VAL), data of co-morbidities, number of health care visits, and prescribed drugs were collected for cases (girls age 12-17 with diagnoses of sexual abuse, n = 519) and controls matched for age and socio-economic status (n = 4920) between 2011-2018. Health care consumption and co-morbidities were significantly higher for the cases compared to controls, with a rise 1 year before the diagnoses: the total number of health care visits (including no shows) 1 year prior to the first recording of the diagnosis was 20.4 (18.1-22.7) for the cases and 6.2 (5.8-6.6) for the controls. The most frequent visits 1 year prior to the diagnosis were to outdoor clinics, with a mean value of 19.1 (16.9-21.3) visits for the cases and 5.7 (5.3-6.1) for the controls, followed by psychiatric clinics with a mean value of 12.7 (10.6-14.8) visits for the cases and 2.0 (1.7-2.3) visits for the controls. The least visited health care clinic 1 year prior to the diagnosis was the emergency ward with a mean value of 1.3 (1.1-1.5) visits for the cases and 0.5 (0.4-0.5) visits for the controls. The most common psychiatric co-morbidities registered among the cases during the first year before the diagnosis of sexual abuse were stress, suicide attempt, and psychosis. Neuroleptics, sleeping pills, antidepressants, and tranquilizers were more frequently dispensed in cases than in controls. Similar patterns were found 2 years prior to the diagnosis. We encourage clinicians to actively ask for exposure of sexual abuse in girls with high health care consumption, making early detection and treatment of sexual abuse available as soon as possible.

Quantitative Flow Imaging in Human Umbilical Vessels In Utero Using Nongated 2D Phase Contrast MRI

BACKGROUND

Volumetric assessment of afferent blood flow rate provides a measure of global organ perfusion. Phase-contrast magnetic resonance imaging (PCMRI) is a reliable tool for volumetric flow quantification, but given the challenges with motion and lack of physiologic gating signal, such studies, in vivo on the human placenta, are scant.

PURPOSE

To evaluate and apply a nongated (ng) PCMRI technique for quantifying blood flow rates in utero in umbilical vessels.

STUDY TYPE

Prospective study design.

STUDY POPULATION

Twenty-four pregnant women with median gestational age (GA) 30 4/7 weeks and interquartile range (IQR) 8 1/7 weeks.

FIELD STRENGTH/SEQUENCE

All scans were performed on a 3.0T Siemens Verio system using the ng-PCMRI technique.

ASSESSMENT

The GA-dependent increase in umbilical vein (UV) and arterial (UA) flow was compared to previously published values. Systematic error to be expected from ng-PCMRI, in the context of pulsatile UA flow and partial voluming, was studied through Monte-Carlo simulations, as a function of resolution and number of averages.

STATISTICAL TESTS

Correlation between the UA and UV was evaluated using a generalized linear model.

RESULTS

Simulations showed that ng-PCMRI measurement variance reduced by increasing the number of averages. For vessels on the order of 2 voxels in radius, partial voluming led to 10% underestimation in the flow. In fetuses, the average flow rates in UAs and UV were measured to be 203 ± 80 ml/min and 232 ± 92 ml/min and the normalized average flow rates were 140 ± 59 ml/min/kg and 155 ± 57 ml/min/kg, respectively. Excellent correlation was found between the total arterial flow vs. corresponding venous flow, with a slope of 1.08 (P = 0.036).

DATA CONCLUSION

Ng-PCMRI can provide accurate volumetric flow measurements in utero in the human umbilical vessels. Care needs to be taken to ensure sufficiently high-resolution data are acquired to minimize partial voluming-related errors.

LEVEL OF EVIDENCE

2 Technical Efficacy Stage 1 J. Magn. Reson. Imaging 2017.

Clinical Outcome in Singleton and Multiple Pregnancies with Placental Chorangioma

INTRODUCTION

Chorangiomas (CAs) are the most common non-trophoblastic tumor-like-lesions of the placenta. Although the clinical significance of small CAs is unknown, the large lesions are often associated with maternal and fetal complications. The aim of our study was to assess the maternal clinical characteristics and neonatal outcome in singleton and multiple pregnancies with placental CA.

MATERIALS AND METHODS

Among 15742 selected placentas 170 CAs were diagnosed. Pregnancy and neonatal outcomes were analyzed in singleton (n = 121) and multiple (n = 49) pregnancy groups including 121 and 100 neonates, respectively.

RESULTS

The frequency of APGAR score <7 at 5 minutes (p = 0,012), abnormal pulsatility index (p = 0,034), and abnormal blood flow class (p = 0,011) were significantly higher in neonates from singleton compared to multiple pregnancies. Significantly smaller CAs in singleton pregnancies were related to small for gestational age neonates (p = 0,00040) and neonates admitted to the neonatal care unit (p = 0,028). In singleton pregnancies, significantly smaller CAs were associated to maternal preeclampsia (p = 0,039) and larger CAs to multiparity (p = 0,005) and smoking (p = 0,001) groups. The frequency of preeclampsia was high in both singleton and multiple pregnancy groups (41,32% vs 26,53%, respectively), however, the difference did not reach the level of statistical significance.

DISCUSSION

A high incidence of preeclampsia in cohort of placental CA might lead to a possible recognition of CAs as potential morphologic indicator of placental hypoxia.

CONCLUSION

A more favorable pregnancy outcome in multiple gestations compared to the singleton gestations with CAs might reflect an adaptive mechanism for increased demand of oxygen and associated placental tissue hypoxia in this group.

Added value of umbilical vein flow as a predictor of perinatal outcome in term small-for-gestational-age fetuses

OBJECTIVE

To compare umbilical vein (UV) flow with standard Doppler parameters in prediction of adverse perinatal outcome in late-onset small-for-gestational age (SGA) fetuses.

METHODS

Umbilical, uterine and middle cerebral arteries, and UV blood flow were evaluated by Doppler before delivery in a cohort of 193 term SGA fetuses. The value of the Doppler parameters to predict risk of emergency delivery for non-reassuring fetal status and neonatal metabolic acidosis was analyzed.

RESULTS

Fifty-three (27%) fetuses had non-reassuring fetal status requiring emergency delivery, whereas 21 (11%) newborns developed neonatal metabolic acidosis. Multivariable analysis showed that significant contributions to prediction of emergency delivery for non-reassuring fetal status and neonatal metabolic acidosis were provided by middle cerebral artery (MCA) pulsatility index (PI) and UV blood flow normalized by fetal weight. Decision tree analysis defined three groups with increasing risk of need for emergency delivery for non-reassuring fetal status: MCA-PI > 1.46 (risk 15.6%); MCA-PI ≤ 1.46 and UV blood flow > 68 mL/min/kg (risk 25%); and MCA-PI ≤ 1.46 and UV flow ≤ 68 mL/min/kg (risk 53.1%); and two groups with different risks of neonatal metabolic acidosis: UV flow > 68 mL/min/kg or UV flow ≤ 68 mL/min/kg and MCA-PI > 1.23 (risk ≤ 10%); and UV flow ≤ 68 mL/min/kg and MCA-PI ≤ 1.23 (risk 39.1%).

CONCLUSION

The evaluation of UV blood flow with spectral brain Doppler allows better identification of SGA fetuses with late-onset intrauterine growth restriction at risk of adverse perinatal outcome.

Laparoscopy guided Doppler ultrasound measurement of fetal blood flow indices during early to mid-gestation in pigs

The objectives of this study were to obtain relevant blood flow indices of umbilical arteries (UmA) of porcine fetuses using a laparoscopic ultrasound probe and to relate these data with fetal size at early to mid gestation. Fetal parameters and flow indices, i.e., fetal length and area, fetal heart rate (FHR), systolic pulse duration (T1), interpulse duration (T2), T2/T1 ratio, peak systolic velocity (PSV), time averaged velocity (TAV), resistance index (RI) and pulsatility index (PI), were measured in 182 fetuses of 26 pregnant Landrace gilts on pregnancy day (PD) 36 (122 fetuses from 17 gilts), PD42 (19 fetuses from 3 gilts) and PD51 (42 fetuses from 6 gilts). Fetal heart rate was higher on PD36 than on PD42 (P<0.05). No differences (P>0.05) were obtained concerning systolic pulse duration, flow velocities and RI. On PD42, the PI was lower (P<0.05), while the interpulse duration (P=0.06) and T2/T1 ratio tended (P=0.08) to be higher on PD42 compared with PD36 and to PD51. To find differences in UmA blood flow parameters concerning fetal size, i.e., fetal length, fetuses were retrospectively grouped as follows: small (lower 25%), medium (mean 50%) and large (upper 25%), respectively. Although, fetuses differed in size (P<0.001) within and between days of pregnancy, FHR, PSV, TAV, RI and PI did not differ (P>0.05) among the size classes. Only systolic pulse duration tended to be longer (P=0.05) in large compared with small fetuses on PD36, and interpulse duration was lower in large fetuses on PD36 in comparison with PD51 (P<0.05). Though there was no link between fetal blood flow indices and fetal intrauterine growth retardation (IUGR), with further studies based on these flow indices, it might be possible to evaluate nutrient- or stress-related influences on fetal growth and development, particularly in the case of IUGR.

Morphological and functional evaluation of normal and abnormal fetal growth by ultrasonography

Correction or estimation of gestational age is essential for the evaluation of fetal growth. When necessary, an appropriate fetal biometric parameter should be selected depending on fetal size. In the first trimester, crown-rump length (CRL) is appropriate, especially when the CRL is 20-40 mm. In the second trimester, biparietal diameter (BPD), head circumference (HC), and femur length (FL) are of equal predictability. Fetal weight estimation is still the basis of evaluation of fetal growth. The most predictable formula currently available includes the parameters BPD (or HC), abdominal circumference (AC), and FL. Serial measurements of AC are useful for diagnosis of intrauterine growth restriction (IUGR) and macrosomia. Quantitative evaluation of soft tissue deposition may be informative for macrosomia. Functional evaluation using Doppler velocimetry is essential in IUGR cases associated with uteroplacental insufficiency. Analysis of blood velocity waveforms of the umbilical and intracranial arteries, predominantly the middle cerebral artery, is widely performed. An increase in the pulsatility index (PI) or resistance index (RI) of the umbilical artery and/or a decrease in the PI or RI of the middle cerebral artery are highly predictable for fetal hypoxia and/or acidosis.

Systolic myocardial velocity alterations in the growth-restricted fetus with cerebroplacental redistribution

OBJECTIVES

Intrauterine growth restriction (IUGR) is associated with cerebroplacental redistribution (CPR), fetal stress and poor outcome, all of which may be related to dysfunction of the fetal myocardium. The aim of this study was to specifically assess myocardial function in IUGR fetuses with CPR in comparison with normal fetuses using color Doppler myocardial imaging (CDMI).

METHODS

CDMI was used to evaluate and compare myocardial velocities in the left and right ventricles in normal fetuses and in IUGR fetuses with CPR. Peak systolic tissue velocities (S') were acquired from both ventricular free walls in 20 IUGR fetuses (gestational age at scan ranged from 26 + 1 to 34 + 6 weeks, with serial measurements obtained in nine) and 42 normal fetuses (35 at week 28, with the remaining seven undergoing serial scans every 4 weeks, ranging from 18 + 6 to 39 + 1 weeks). Umbilical artery (UA), middle cerebral artery (MCA) and ductus venosus (DV) flows were also recorded.

RESULTS

Left and right S' increased with gestational age in normal pregnancy. Fetuses with IUGR and CPR had lower left ventricular S' than normal fetuses (mean, 2.41 (95% CI, 1.96-2.86) cm/s vs. 3.30 (95% CI, 3.05-3.55) cm/s; P = 0.0006). This reduction in S' correlated with the grade of UA flow abnormality (P = 0.0002). Fetuses with reversed diastolic UA flow had significantly lower left S' (mean, 2.0 (95% CI, 1.4-2.6) cm/s; P = 0.001) than normal fetuses. There was no correlation between left S' and MCA pulsatility index (P = 0.37) in the IUGR-CPR group, but there was a reduction in S' approaching statistical significance in fetuses with reversed DV flow in comparison to those without it (P = 0.09). Right S' was similar in the two study groups and did not correlate with worsening UA flow class. All fetuses with a left S' below 1.6 cm/s and reversed UA flow died in the perinatal period.

CONCLUSIONS

CDMI facilitates acquisition of fetal myocardial ventricular S'. The combination of IUGR and CPR is associated with a reduced left ventricular S', especially in those with reversed UA flow. In this subgroup a left S' below 1.6 cm/s seemed to predict mortality in the perinatal period.

Effect of a cholesterol-lowering diet during pregnancy on maternal and fetal Doppler velocimetry: the CARRDIP study

OBJECTIVE

The purpose of this study was to evaluate the effect of a low-cholesterol low-saturated fat diet on Doppler indices in the fetus and mother.

STUDY DESIGN

Two hundred ninety nonsmoking white women, aged 21-38 years, without previous pregnancy complications and carrying a single fetus were assigned randomly to continue their usual diet (control subjects; n = 149) or to adopt a low-cholesterol low-saturated fat diet (intervention group; n = 141) from gestational week 17-20 to birth. Doppler velocimetry of the umbilical artery and both uterine arteries were assessed at gestational weeks 24, 30, and 36.

RESULTS

The physiologic gestational decrease in umbilical artery pulsatility index (PI) from week 24-30 was more pronounced in the intervention group, compared with the control group, with median values (interquartile range) of -0.17 (-0.29, -0.06) and -0.11 (-0.25, 0.01), respectively (P = .048). Assignment to the intervention diet did not influence the changes in mean PI value of the 2 uterine arteries (P = .3). The change in umbilical artery PI and mean PI value of the uterine arteries between weeks 24 and 36 were not significantly different between the 2 groups (P = 1.0 and .2 respectively).

CONCLUSION

Our study shows that a cholesterol-lowering diet during pregnancy may modify fetoplacental circulation in mid pregnancy.

Time domain measurement of blood flow in the human fetal aorta during normal pregnancy

OBJECTIVE

To evaluate blood-volume flow-rate measurement in the fetal descending thoracic aorta using a non-invasive, non-Doppler, ultrasound technique.

METHODS

This was a cross-sectional, observational study. Volume flow measurements were obtained from the descending thoracic aorta in 59 human fetuses between 20 and 40 weeks' gestation. These were uncomplicated pregnancies that resulted in the live births of appropriately grown infants. The measurements were obtained using a time domain processing technique: color velocity imaging quantification (CVI-Q).

RESULTS

The blood-volume flow rate increased consistently from the second trimester until term. The mean values ranged between 100 mL/min at 20 weeks' gestation and approximately 350 mL/min at term. The normalized (weight-adjusted) volume flow rates decreased with increasing gestation, from a maximum of 626 mL/min/kg at 23 weeks to a minimum of 45.6 mL/min/kg at 37 weeks.

CONCLUSIONS

The regular measurement of blood-volume flow in the descending fetal thoracic aorta is feasible using CVI-Q. Although there is a considerable learning curve, with adequate training there are potential clinical applications for this non-Doppler technique. However, limitations exist with the currently available technology for clinical use in fetal vascular studies.

The value of the soluable intercellular adhesion molecule-1 levels in matermal serum for determination of occult chorioamnionitis in premature rupture of membranes

To compare the diagnostic value of soluble intercellular adhesion molecule 1 (sICAM-1) with that of c-reactive protein (CRP) for detecting chorioamnionitis (CAM) in serum of women with premature rupture of membranes (PROM), 55 pregnant women with PROM, including 18 pregnant women with preterm premature rupture of membranes (PPROM) and 20 normal pregnant women at term (TPROM) were studied. Maternal serum were measured by Sandwish enzyme-linked immunoabsorbent assay (ELISA) for sICAM. CAM was histologically confirmed after delivery. The results revealed that (1) maternal serum levels of sICAM-1 and CRP were significantly higher in women with PROM than those without it; (2) maternal serum levels of sICAM-1 and CRP were significantly higher in women with CAM than those without it; (3) serum levels of sICAM-1 in PPROM women were similar to those in TPROM women, whereas serum levels of CRP in PPROM women were significantly higher than those in TPROM women; (4) the sensitivity, specificity, positive predictive value, negative predictive value, Kappa index and area under receiver operating characteristic (ROC) curve of maternal serum sICAM-1 (cutoff 104.7 ng/ml) and CRP (cutoff 1.03 mg/dl) for diagnosing CAM were 100%, 91.2%, 87.5%, 100%, 0.20, 0.995 and 81.0%, 73.5%, 65.4%, 86.2%, 0.13, 0.811, respectively; (5) among the mild histological CAM group, severe histological CAM group and clinical CAM group, the difference in maternal serum levels of sICAM-1 were significantly (P<0.001), with the order of concentration from high level to low level corresponding to the severity of CAM. It is concluded that maternal serum level of ICAM-1 is superior to that of CRP as biomarker for diagnosing intraamniotic infection in pregnant women with PROM.

Relationships among Doppler-derived umbilical artery absolute velocities, cardiac function, and placental volume blood flow and resistance in fetal sheep

We hypothesized that umbilical artery (UA) absolute blood flow velocities measured by Doppler ultrasonography reflect placental volume blood flow (Q(UA)) and placental vascular resistance (R(UA)) in a late gestation fetal sheep model. In addition, we examined the relationships between umbilical artery absolute blood flow velocities and parameters of fetal cardiac function. Twenty-six sheep fetuses were instrumented at 112-132 days of gestation. After a 5-day recovery period, experiments were performed under general anesthesia in 16 normal fetuses, in 5 fetuses after maternal administration of phenylephrine, and in 5 fetuses after placental embolization. The Q(UA) and arterial blood pressures were measured using a transit-time ultrasonic flow probe and a catheter placed into the descending aorta, respectively. UA peak systolic velocity (PSV), end-diastolic velocity (EDV), time-averaged maximum velocity (TAMXV), pulsatility index (PI), mean velocity (V(mean)), fetal cardiac output, ventricular ejection forces, and the proportion of isovolumetric relaxation time (IRT%) in the cardiac cycle were measured with the use of Doppler ultrasonography. Significant positive linear correlations were found between UA EDV, TAMXV, and V(mean) versus Q(UA), whereas UA PI had a significant negative correlation with Q(UA). Significant negative correlations were shown between UA EDV, TAMXV, and V(mean) versus R(UA). A significant positive correlation was present between UA PI and R(UA). Doppler-derived UA parameters did not correlate with fetal arterial blood pressures, cardiac output, ventricular ejection forces or IRT%. In fetal sheep, Doppler-derived UA PI and absolute velocities, except PSV, are closely related to directly measured Q(UA) and R(UA), validating the use of noninvasive Doppler velocimetry in the assessment of placental circulation.

The predictive value of plasma fibronectin concentration on fetal growth retardation at earlier stage of the third trimester

In order to evaluate the predictive value of maternal plasma fibronectin (FN) concentration at 24-34 weeks on fetal intrauterine growth retardation (IUGR), a prospective double-blinded study was performed. The maternal plasma FN concentrations were measured by using a rate nephelometric procedure in the 130 initial normal nulliparous pregnant woman at 24-34 gestational weeks. The outcome of pregnancies and birth weight of their infants were followed up. IUGR was defined as that the birth weight was less than the 10th percentile for gestational age. The receiver operating characteristic curves and predictive values of FN predicting on outcome of pregnancy with IUGR were analyzed. The results showed that: (1) In a cohort of 130 initially normal nulliparous pregnant women, IUGR occurred in 14 cases during the follow-up; (2) The plasma FN levels in the women with IUGR (467.58 +/- 104.43 mg/L) were significantly higher than in the normal control group (299.44 +/- 105.55 mg/L, P < 0.01). However, there was no significant difference in the mean maternal age, gravidity, sampling gestational ages, delivering gestational ages between the two groups (P > 0.05); (3) The areas under ROC curve for predicting the outcome of pregnancy in IUGR was 0.893; (4) At the cut point of 475 mg/L FN level, the sensitivity, specificity, positive predictive value, negative predictive value and Kappa index for predicting the outcomes of pregnancy in IUGR were 57.14%, 95.69%, 61.54%, 94.87%, 0.5455 respectively. It was concluded that the maternal plasma FN might be used as an earlier predictor for screening of IUGR.

Umbilical vein blood flow in growth-restricted fetuses

OBJECTIVE

To determine whether umbilical blood flow is reduced in a subset of growth-restricted (IUGR) fetuses when expressed as flow per kilogram or flow per unit of specific sonographic fetal measurements.

DESIGN

Prospective.

SUBJECTS

Thirty-seven IUGR fetuses were examined by Doppler ultrasound within 4 h of the last non-stress test prior to delivery. This population was divided into three groups of varying clinical severity according to the characteristics of umbilical arterial pulsatility index (PI) and heart rate.

METHODS

Absolute and weight-specific umbilical vein (UV) flow were calculated from measurements of UV diameter and UV mean velocity. Umbilical vein diameter, velocity and UV flow were calculated also per unit head (HC) or abdominal circumference (AC) and correlated with gestational age.

RESULTS

Umbilical vein flow (UVf) per kilogram fetal weight was significantly lower in the more severe IUGR fetuses (abnormal umbilical arterial PI) than in normally grown comparable fetuses (P < 0.001). Umbilical vein flow per unit HC was significantly lower in the three groups (P < 0.001) than in the control population. The UV diameter/HC ratio was normal whereas UV velocity/HC ratio was significantly lower in IUGR fetuses than in comparable controls.

CONCLUSIONS

The present study clearly establishes that umbilical venous blood flow is reduced in IUGR fetuses on a weight-specific basis. The sonographic growth parameter which best distinguishes umbilical flow differences of IUGR fetuses from normal fetuses is the head circumference.

Critical comparison of indices and threshold values for assessing placenta performance using Doppler ultrasound

To determine the most appropriate index and an optimal cutoff value for obstetric Doppler ultrasound, the umbilical and uterine arteries of 467 patients were examined during the third trimester using an Acuson 128 color Doppler system. Doppler ultrasound detection of chronic placental insufficiency with fetal growth retardation and acute placental insufficiency with subpartal asphyxia were selected as criteria. A birth weight below the 10th percentile (using Hohenauer's percentiles) was taken as the parameter for the former and a 5-minute Apgar score of < 8 for the latter criterion. For each artery, two risk groups were studied: 103 patients with chronic and 27 patients with acute placental insufficiency. Using EROC curves, the prediction of chronic and acute placental insufficiency was computed for six Doppler indices (maximum systolic, mean [TAMX] and maximum end-diastolic velocities, S/D ratio, RI, PI) and 10 threshold values per index (the 1st to 50th percentiles for the qualitative indices and the 50th to 99th percentiles for the quantitative indices). The following results were obtained: (1) the development of chronic placental insufficiency was predicted best in Doppler examinations of the umbilical artery by calculating the PI with the 60th percentile as the threshold value, and in examinations of the uterine artery by determining the S/D ratio with the 90th percentile; 2nd (2) acute placental insufficiency was predicted best by calculating the mean blood flow velocity (TAMX) in the umbilical artery, with the 50th percentile as the ideal cutoff value; in examinations of the uterine artery the best results were obtained by determining the S/D ratio with the 90th percentile as cutoff value. Three conclusions may be drawn from the results: (1) taken overall, the qualitative Doppler parameters (S/D ratio, RI, PI) are superior to the quantitative parameters (maximum systolic, mean [TAMX] and maximum end-diastolic velocity) in the detection of both chronic and acute placental insufficiency; (2) in Doppler examinations of the umbilical artery the optimal threshold value is in the region of the 60th, and in examinations of the uterine artery in the region of the 90th, percentile; and (3) chronic placental insufficiency was detected better than the acute form; examinations of the umbilical artery yielded more explicit data than those of the uterine artery.

Prediction of perinatal morbidity at term in small fetuses: comparison of fetal growth and Doppler ultrasound

OBJECTIVE

To compare fetal growth assessed by ultrasound (change in standard deviation score of abdominal circumference and estimated fetal weight) during the third trimester with predelivery ultrasound measurements of fetal size and Doppler measurements from the umbilical and fetal arteries in order to predict suboptimal perinatal outcome in small babies at term.

DESIGN

Prospective observational study.

SETTING

Day assessment unit in a university hospital.

SUBJECTS

One hundred and four consecutive women with a clinical suspicion of a small fetus during the third trimester confirmed by ultrasound (abdominal circumference below the 10th centile) and ultimately delivered at term.

MAIN OUTCOME MEASURES

Acidaemia at birth, fetal distress requiring emergency caesarean section in labour, admission to the neonatal intensive care unit.

RESULTS

Ninety-four babies (90%) weighed less than the 10th centile and the incidence of suboptimal perinatal outcome was 27%. The largest areas under the receiver operating characteristic curves for suboptimal perinatal outcome were obtained with the change in standard deviation score of abdominal circumference and estimated fetal weight, and the ratios of aortic/middle cerebral and renal/middle cerebral pulsatility index. Although low, the odds ratios of the change in estimated fetal weight standard deviation score and the Doppler ratios were significantly different from zero.

CONCLUSION

Ultrasound assessment of fetal growth and predelivery fetal Doppler pulsatility index ratios were superior to predelivery estimates of fetal size and umbilical artery pulsatility index in predicting suboptimal perinatal outcome in small fetuses delivering at term, although the clinical value of such a prediction may be limited.

Recent advances in the use of Doppler waveform indices in the antenatal assessment of intrauterine growth retardation

Doppler ultrasound has been advocated as a useful tool to evaluate pregnancies with intrauterine growth retardation (IUGR). However, many previous studies have used smallness for gestational age (SGA) at birth to define IUGR. The ability of Doppler ultrasound to predict SGA, neonatal morphometric indices of wasting such as a low ponderal index, and perinatal morbidity is reviewed. Doppler assessment of the umbilical and uteroplacental vasculatures were inferior to ultrasound measurements of fetal size in the prediction of SGA. In low risk fetuses, umbilical artery waveform indices were of limited value in the prediction of neonatal morphometric indices of wasting. Within a group of high risk fetuses, Doppler assessment of the umbilical artery and, in particular, the middle cerebral and aortic vessels, were useful in predicting fetuses with neonatal wasting. Similar findings were noted in the prediction of perinatal morbidity. The review confirms the usefulness of umbilical artery Doppler waveform indices in the antenatal assessment of IUGR. Whilst preliminary studies appear to suggest that Doppler waveform indices of the middle cerebral and aortic vessels may confer an additional advantage in the antenatal assessment of IUGR, randomized controlled trials evaluating their effect on perinatal outcome and studies on the reproducibility of these indices need to be carried out before their widespread introduction into obstetric practice.

Umbilical artery Doppler flow-velocity waveforms and fetal acid-base balance in Rhesus-isoimmunized pregnancies

Pulsed Doppler blood-flow velocity waveforms in the umbilical arteries, as well as blood gases, hematocrit, and lactate concentration in umbilical venous blood, were examined in 21 patients undergoing 49 cordocentesis, 34 of which were followed by fetal blood transfusion into the umbilical vein. The aim of the study was to evaluate the correlations, if any, between the Doppler indices from the umbilical artery (pulsatility index, resistance index, systolic/diastolic ratio) and the blood gas values (pO2, pCO2, O2 content, pH) and lactate content in the umbilical vein. The only correlation confirmed in this study was in the subgroup of anemic fetuses undergoing fetal blood transfusion, where correlation existed between A/B and the initial O2 content (r = -0.41, p < 0.02). We conclude that, in Rhesus-isoimmunized pregnancies, in contrast to other pregnancies, a close correlation does not exist between the Doppler indices in the umbilical artery and the fetal blood gas values.

Antenatal diagnosis of intrauterine growth retardation by ultrasound

Ultrasound estimation of fetal weight or ultrasound measurement of fetal abdomen alone enables identification of small-for-gestational-age fetuses. A prerequisite for this is a reliable dating of pregnancy, which is provided by a routine ultrasound screening in the first half of gestation. The fetal growth can be followed by serial fetometric measurements. As a standard, charts of intrauterine growth based on the ultrasonic measurement can be used. As a secondary diagnostic test for monitoring fetal health in pregnancies suspected of intrauterine growth retardation, Doppler ultrasound evaluation of fetal and uteroplacental hemodynamics provided useful for early detection of imminent fetal distress.

Relationship between fetal cardiac and extra-cardiac Doppler flow velocity waveforms and neonatal outcome in intrauterine growth retardation

In a total of 42 consecutive pregnancies with intrauterine growth retardation (IUGR), Doppler velocimetry was related to neonatal outcome as determined by Apgar score at 1 min, umbilical artery acid-base status and PO2, number of nucleated red blood cells (NRBC), duration of ventilatory support, and sonographic appearance of cerebral leukomalacia. Doppler flow velocity waveforms were obtained from the ascending aorta (AO), pulmonary artery (PA), internal carotid artery (ICA) and umbilical artery (UA) at 2-3 day intervals until delivery. At cardiac level the peak systolic velocity (PSV) and time-averaged velocity (AV), and at peripheral level the pulsatility index (PI) was determined. As all Doppler parameters were significantly related to gestational age at birth, gestational age was taken into account in the analysis. There was no relationship between Apgar score, acid-base status and Doppler parameters. Low AVAO was related to a low umbilical artery PO2. Significant correlations were established between PSVPA, AVPA and PIUA, and the duration of neonatal ventilatory support. Infants who died within 22 days after admission to the neonatal intensive care unit (n = 7) displayed a significantly higher PIUA than those who remained alive. The PIUA was also related to the absolute and relative number of NRBCs. No relationship existed between the Doppler parameters and degree of leukomalacia. The present study demonstrates that from all Doppler parameters, the PIUA is most clearly related to neonatal outcome in IUGR.

Fetal umbilical artery velocity waveforms and subsequent neonatal outcome

Flow velocity waveforms (FVWs) from the fetal umbilical artery were recorded from 2178 pregnant women over a 6-year period. All of them had an obstetric factor indicating increased risk of fetal compromise. A total of 6749 studies was recorded. The systolic diastolic (AB) ratio was measured and classified as normal (less than 95th centile), elevated (95-99th centile), high (greater than 99th centile) or extreme (absent diastolic flow). The results of these studies have been related to subsequent fetal and neonatal outcome. An abnormal umbilical artery FVW was associated with shorter gestation and infants with lower birthweight, shorter length and lower ponderal index. There was a highly significant association between an abnormal FVW and the birth of an infant small for gestational age. The significance of the association increased with the increased abnormality of the umbilical artery FVW and this was independent of gestational age. Preterm infants associated with high or extreme AB ratios spent twice as long in the neonatal nursery than those with normal AB ratios. Analysis of 794 pregnancies studies serially indicated that an abnormal FVW in which the AB ratio was increasing, in contrast to a decreasing AB ratio, predicted a poor outcome for both size at birth and duration of neonatal intensive care. We conclude that in high risk pregnancy Doppler umbilical artery FVW studies predict the most compromised fetuses in terms of growth retardation and requirements for neonatal intensive care.

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.

Cord blood gases and absence of end-diastolic blood velocities in the umbilical artery

Umbilical artery and vein blood gases were compared in three groups of pregnant women delivered by elective caesarean section: group 1 (n = 21), normal controls; group 2 (n = 15), complicated pregnancies with normal umbilical artery blood flow velocity waveforms; and group 3 (n = 14), complicated pregnancies with absent end-diastolic blood velocity in the umbilical artery. Newborns in group 3 were found to be small for gestational age and to have significantly lower oxygen pressure and saturation. These fetuses were thus in a state of chronic hypoxia, which may predispose for development of intra-uterine distress. Doppler ultrasound examination can be useful in identifying this high risk group requiring intensified surveillance.

Abnormal velocity waveforms of the umbilical artery in growth retarded fetuses: relationship to antepartum late heart rate decelerations and outcome

In 70 intrauterine growth-retarded (IUGR) fetuses with antepartum late heart rate decelerations recordings of velocity waveforms of the umbilical artery were made with Doppler ultrasound and calculated as pulsatility indexes (PI). In 29 of these fetuses longitudinal recordings were made. Abnormal PIs preceded the occurrence of late heart rate decelerations in 27 (93%) of the 29 fetuses. The median duration of the interval between the first abnormal PI and the first appearance of antenatal heart rate decelerations was 17 days (range 0-60 days). This wide range can mainly be attributed to the gestational age at which the first abnormal velocity wave-form was recorded; during early gestation the interval was much longer than later in pregnancy. Absent end-diastolic velocity (AEDV) was found in 17 of the 29 fetuses (59%) and preceded the occurrence of decelerations with a median interval of 12 days. In the total group, 4 of the 70 IUGR fetuses with antepartum decelerations had a normal velocity waveform of the umbilical artery. Fetuses with AEDV (n = 45) were more severely growth retarded and were delivered at an earlier gestational age than those with end-diastolic velocity (n = 25). Also perinatal mortality and morbidity were higher in the group with AEDV. Yet, when fetuses were matched for gestational age and birth weight no differences in perinatal outcome were found in the groups with and without end-diastolic velocity.

Large placental chorioangioma as a cause of congestive heart failure in newborn infants

Two rare cases of infants born from pregnancies complicated by large placental chorioangiomas are reported. Congestive heart failure occurred early in the neonatal period as the main complication. Chorioangiomas may be diagnosed early in pregnancy by ultrasound examination. Since both maternal and neonatal complications may indicate premature termination of the pregnancy or be conducive to premature birth, repeated ultrasound examinations, including fetal echocardiography and flow measurements, are suggested to determine the optimal time of delivery. Possible pathophysiological mechanisms causing neonatal complications are discussed.

Measurement of arterial blood flow by Doppler ultrasound

A review is given of quantitative techniques and clinical applications of arterial Doppler ultrasound. The currently available Doppler equipment of stand-alone continuous wave and pulsed wave units, duplex systems and colour flow systems is briefly described. Doppler ultrasound can be divided into procedures concerned with waveform analysis, volume flow measurement and more recently colour flow imaging. Arterial Doppler waveform analysis is considered for a number of areas including carotid, lower limb, renal and renal transplant, obstetrics, adult cerebral, neonatal cerebral, and tumour studies. Using a duplex scanner volume flow in arteries can be measured from estimates of vessel cross sectional area, mean Doppler frequency and beam-vessel angle. The errors associated with each of these measurements is discussed, and reports of experimentally determined in vivo accuracy of volume flow measurements made using this technique are considered. Other volume flow measurement techniques including the promising attenuation compensation method are also explored.

Stillbirths: a clinicopathological survey (1972-1982)

A survey of 325 stillbirths from 27,072 babies delivered at University College Hospital Galway from April 1, 1972 to March 31, 1982, gave a stillbirth rate of 12 per thousand, which, when corrected for 66 lethal congenital abnormalities, became 9.6 per thousand. The cause of death in each stillbirth was determined clinically and pathologically where possible and was classified according to a modified Aberdeen classification of perinatal death. Consideration of the birth weights of the babies who died showed that 223 (68.6%) weighed over 1,500 g, and excluding those with abnormalities, they must be considered salvageable with the application of intensive neonatal care. There were 54 (16.6%) intrapartum deaths, which must also be considered preventable. The application of ultrasonic surveillance should complement clinical acumen, by allowing easier detection of the fetus at risk, thereby facilitating earlier intervention which in turn should reduce antenatal stillbirths.

Characteristics of Doppler blood-velocity waveforms in a cardiovascular in vitro model. I. The model and the influence of pulse rate

In order to study the indices describing the flow-velocity curves a cardiovascular in vitro model has been constructed. The model consists of two parts: (i) A heart simulator producing controllable cardiac output, pulse rate and pressure variations, (ii) a circulatory system made of elastic butyl rubber tubes with adjustable peripheral resistance bed. The flow-velocity curves were obtained by a Doppler velocity meter as a function of the pulse rate (PR) when pressure, volumetric flow, and peripheral resistances were constant. The four evaluated indices, pulsatility index (PI), peak velocity (Vpeak), rising slope (RS) and A/B ratio (A/B i.e. maximum/minimum velocity ratio) all showed significant correlation with pulse rate. PI, A/B and Vpeak showed a marked increased at low pulse rate and the inverse relation between these indices and pulse rate were best described by power functions, whereas RS was found to be inversely proportional to pulse rate. The results are in good agreement with the few existing clinical observations, and we suggest that the relations described are taken into consideration in the clinical interpretation of blood velocity indices.

Characteristics of Doppler blood-velocity waveforms in a cardiovascular in vitro model. II. The influence of peripheral resistance, perfusion pressure and blood flow

A cardiovascular in vitro model was used to examine the influence of peripheral resistance on the Doppler blood-velocity waveforms. In the study the velocity indices were determined as a function of peripheral resistance either with the flow kept constant (the perfusion pressure varied) or with the pressure constant (the flow varied). The peak velocity (Vpeak) is normally accepted as a simple expression of the stroke volume. However, in this study Vpeak did increase with resistance when the stroke volume was constant. Rising slope (RS) is said to correlate with heart contractility, but in this study such a relation was not found. Pulsatility index (PI) and A/B ratio (A/B) are normally considered to reflect peripheral resistance. PI was found to be a flow- and pressure-independent proportional expression of peripheral resistance. A/B also increased with resistance but this relationship is more uncertain. The results of this in vitro study support the clinical use of PI as a flow- and pressure-independent estimate of peripheral resistance. The relation of RS and Vpeak to heart contractility and stroke volume, respectively, is found to be dependent also on resistance, blood flow, and pressure.

A comparison of fetal abdominal circumference measurements and Doppler ultrasound in the prediction of small-for-dates babies and fetal compromise

A total of 145 pregnancies clinically suspected of being small-for-dates was studied at presentation with a single measurement of the fetal abdominal circumference and Doppler studies of the umbilical and arcuate arteries. The abdominal circumference measurement gave the best prediction of the small-for-gestational-age (SGA) baby (sensitivity 73%, umbilical artery sensitivity 47%, arcuate artery sensitivity 29%). The umbilical artery measurement gave the best prediction of antenatal fetal compromise; the performance of the tests was compared for a fixed sensitivity of 100% (i.e. all cases of antenatal compromise would be detected), the specificity of the umbilical artery measurement was 77%, abdominal circumference measurement 12% and arcuate artery measurement 2%. In our data, umbilical artery studies were not a sensitive predictor of the SGA baby but they did give an accurate prediction of the potentially compromised SGA fetus.

Abnormal antenatal ultrasound findings and subsequent handicap

The modern ultrasound technique in its various modes, real-time B-mode, M-mode, continuous and pulsed wave Doppler ultrasound, makes it possible to study in detail the fetal anatomy and function in utero. Fetometry allows for the evaluation of fetal size and growth and for detecting growth-retarded or macrosomic fetuses. Ultrasound seems, at present, to be the best method available in the detection of the growth-retarded fetus who is at risk of developing perinatal complications and subsequent handicap. Ultrasound can also be used when fetal growth retardation is suspected on clinical grounds. An absolute prerequisite for the proper use of ultrasound fetometry is the estimation of gestational age in early pregnancy. The high resolution of modern ultrasound scanners allows the antenatal detection of even minor fetal structural abnormalities. When lethal malformations are detected early in pregnancy, selective termination of pregnancy can be considered. Fetal abnormality detected in late pregnancy allows for optimal timing and mode of delivery leading to improved management and outcome, thus lowering the risks of subsequent handicap. Ultrasound examination of the extrafetal structures, e.g. umbilical cord, placenta and amniotic fluid volume, may add valuable clinical information. The finding of severe oligohydramnios is associated with increased perinatal mortality and morbidity. Fetal circulation can be evaluated by using the combination of real-time and pulsed Doppler ultrasound or, alternatively, by employing continuous wave Doppler ultrasound alone. Pathological changes in the blood velocity waveforms recorded from the fetal and umbilical arteries may signify very early signs of fetal hypoxia. The method has the potential of becoming a useful clinical method for fetal surveillance. The guidelines for a proper application in the perinatal medicine of the Doppler method have, however, not yet been established. In fetuses with cardiac arrhythmia and/or cardiac malformation, the Doppler investigation of the fetal circulation can be used to evaluate the haemodynamic alterations and, in cases of intrauterine treatment, to supervise and monitor the therapeutic effects. Fetal motor function can be followed and quantified with real-time ultrasound. Abnormal motor activity might indicate bad perinatal outcome. The predictive capacity of the test is increased when several variables are combined (e.g. the fetal biophysical profile score).(ABSTRACT TRUNCATED AT 400 WORDS)