Middle cerebral artery blood flow in the fetus and central nervous system complications in the neonate.

OBJECTIVE: To evaluate the ability of blood flow (S/D) ratios in the fetal middle cerebral artery (MCA) to predict the occurrence of central nervous system (CNS) complications (bleeding and/or ischemia) in the neonate, and compare MCA flow to other tests of fetal well-being. STUDY DESIGN: This was a retrospective, observational, cross-sectional clinical outcome study of high-risk patients, evaluated in the Perinatal Center of the author's institution, who underwent antenatal testing with non-stress test (NST) and Doppler studies (including studies of the fetal umbilical artery and MCA) within 1 week of delivery. MCA flow was converted to multiples of the mean, and appropriate parametric and non-parametric statistics were used to compare MCA flow to the presence or absence of CNS complications. Comparisons were also made for the other tests of fetal well-being. RESULTS: CNS complications occurred only in infants who were delivered at less than 37 weeks of gestation (n = 14/131) and the analysis was limited to these 131 patients. Univariant analysis showed that only the NST correlated with CNS complications (OR = 5.46 (1.48-22.16)) and logistic regression confirmed the association. Neither increased diastolic flow in the MCA nor the presence of shunting correlated with CNS complications. CONCLUSIONS: This study confirms previous reports that fetal shunting, with decreased resistance and increased flow in the CNS, is a benign adaptive mechanism for the fetus under stress and not an increased risk for CNS complications. A non-reactive NST, however, is a very late sign of fetal compromise and is significantly associated with the risk of developing CNS complications.

Obstetric ultrasonographic findings and fetal chromosomal abnormalities: refining the association.

OBJECTIVE: In an attempt to refine the role of ultrasonography in screening and identifying fetuses at risk for chromosomal abnormalities, a retrospective review of patients undergoing genetic amniocentesis was undertaken. STUDY DESIGN: Computer databases from the perinatal biology laboratory and cytogenetics laboratory of our institution were correlated to compare the results of the fetus' ultrasonographic examination with the cytogenetic results from amniocentesis. Univariate and multivariate analysis were used to determine the best correlations between ultrasonographic findings and chromosomal abnormalities (study 1). The results were used to construct regression analysis formulas and a Neural Network program to predict the presence or absence of chromosomal abnormalities in a second set of patients (study 2) undergoing genetic amniocentesis. RESULTS: One hundred twenty-five chromosomal abnormalities were found in 3775 fetuses in study 1 (3.3%). Multivariate analysis showed significant correlations between anomalies of the central nervous system, heart, face and neck, and extremities and increased nuchal fold, increased bowel echogenicity, abnormal biparietal diameter-to-femur ratio, and the presence of chromosomal abnormalities. Regression equations and a Neural Network program successfully predicted the presence or absence of fetal chromosomal abnormalities in a second set of 901 at-risk fetuses. CONCLUSION: A normal ultrasonographic examination result in patients who are at increased risk for fetal chromosomal abnormalities reduces the risk 2- to 3-fold, whereas the presence of any major ultrasonographic abnormality or certain minor abnormalities significantly increases the risk. The application of these results to low-risk patients is still premature.

Intrauterine growth restriction and Doppler ultrasonography.

To clarify the difference between the fetus that is small for gestational age and the fetus with true intrauterine growth restriction, we undertook a retrospective study of singleton fetuses who had fetal weight estimation and umbilical artery Doppler velocity studies within 2 weeks of their delivery. Fetuses were divided into four categories on the basis of sonographic results from their last examination. Statistical comparisons of neonatal outcome were made for the four groups, which totaled 578 fetuses. Increased cesarean section for fetal distress, stays in the neonatal intensive care unit, and increased neonatal morbidity were seen in both small for gestational age and average for gestational age neonates with abnormal Doppler blood flow. The small for gestational age fetuses with normal Doppler studies showed no increased morbidity when compared with their average for gestational age cohorts. Umbilical artery Doppler blood flow studies were a better predictor of neonatal outcome than estimated fetal weight. Small for gestational age fetuses with normal Doppler studies most likely represent constitutionally small, not pathologically growth restricted, fetuses.

Comparison of the non-stress test with the evaluation of centralization of blood flow for the prediction of neonatal compromise.

OBJECTIVE: To determine whether the middle cerebral to umbilical artery systolic/diastolic velocity waveform ratio (MC/UA) was a more sensitive indicator of fetal compromise than the non-stress test (NST). STUDY DESIGN: An outcome study of high-risk patients undergoing NST testing and MC/UA studies within 10 days of delivery. Patients were divided into four groups based on their test results, and neonatal outcome parameters were compared. RESULTS: There were significant differences between all four test result groups with respect to length of stay in the neonatal intensive care unit (NICU). Patients in whom both the NST and MC/UA ratio were normal had significantly lower utilization of Cesarean section for delivery, admission and length of stay in the NICU and occurrence of significant neonatal complications. Logistic regression analysis indicated that the combination of the NST and MC/UA ratio was an excellent predictor of perinatal outcome. CONCLUSIONS: The MC/UA ratio improves the sensitivity for the prediction of poor perinatal outcome when it is combined with the NST.

Value of inferior vena cava Doppler waveform analysis for prediction of neonatal outcome.

The objective of this article is to determine the value of the inferior vena cava preload index (IVC) to predict neonatal outcome and compare it to other biophysical methods of antenatal surveillance. A clinical outcome study of patients referred to the author's institution for Doppler velocity blood flow studies was undertaken by comparing the ability of three antenatal surveillance tests: the nonstress test (NST); umbilical artery S/D ratio (UA); and the ratio of the middle cerebral artery to umbilical artery S/D ratios (MCUA) to predict poor neonatal outcome to the ability of the IVC to predict poor outcome. Patients were followed serially and neonatal outcome data was tabulated. Those patients that delivered within 10 days of their last study were included in the analysis. Seventy patients met the inclusion criterion. Neonatal outcome based on the results of the IVC as compared with outcome based on the results of the NST, UA, and MCUA tests. Odds ratios (with 95% confidence limits) for significant neonatal morbidity predicted by each test were: NST: 2.6 (0.14-14.6); UA: 5.7 (1.7-18.8); MCUA: 3.6 (1.1-13.1); and IVC: 4.1 (1.3-13.2). Logistic regression analysis indicated that the combination of MCUA and IVC was the best method of predicting poor neonatal outcome. This study of the utility of fetal IVC suggests that this noninvasive method of antenatal surveillance may provide an additional sensitive method of evaluating the status of the high-risk fetus.

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.

Sonographic diagnosis of intrauterine growth restriction.

Estimation of fetal weight in utero using multiple ultrasonic parameters remains the mainstay in screening for IUGR. The use of various fetal morphometric ratios and/or measurements of other fetal parameters may provide additional useful information. Serial evaluation to assess interval growth may be necessary to clarify the diagnosis. The use of Doppler ultrasound, especially the evaluation of the umbilical artery and middle cerebral artery velocity flow, is an important adjunct for both the diagnosis of IUGR caused by uteroplacental insufficiency and its continued management.

Comprehensive ultrasound examination in a private perinatal practice.

A retrospective review of the types of patients seen and the accuracy of the diagnosis made was undertaken for patients referred for comprehensive ultrasound examination in a large private perinatal practice. A review of the perinatal ultrasound database, neonatal intensive care database, and hospital charts was done in 1338 patients referred to the perinatal ultrasound laboratory for comprehensive ultrasound examination during a 2-year period. Accuracy of the ultrasound diagnosis and relationships between structural anomalies seen on ultrasound examination and perinatal outcome was undertaken. Positive and negative predictive values for the ultrasonic diagnosis were 82% and 98%, respectively. There were 19 (1.4%) false-positive diagnoses and 38 (2.8%) false-negative diagnoses. There was a high correlation between structural anomalies and chromosomal anomalies, with 15 of the 87 infants (17.2%) with structural anomalies also having chromosomal anomalies. The accuracy of ultrasonic diagnosis for comprehensive examinations in a large private perinatal practice compared favorably with previous reports in the literature. The information presented in this study should be helpful to obstetric centers with similar patient populations.

Small for gestational age fetus and neonatal outcome: reevaluation of the relationship.

A retrospective review of 1316 neonates who had been evaluated in the Perinatal Laboratory of my institution during the years 1990 and 1991 was undertaken to study the relationship between birthweight for gestational age, maternal high-risk factors, and neonatal ponderal index with neonatal outcome. Patients were stratified as to gestational age at delivery and the presence of significant congenital abnormalities. Univariant analysis (chi square or t test, where appropriate) was done comparing neonatal outcome for neonates that were or were not small for gestational age (SGA), whose mother did or did not have high-risk factors, and for infants with normal or abnormal ponderal indices. Multivariant analysis was also done using logistic regression analysis. In infants without congenital anomalies delivering at term only the presence of maternal risk factors had prognostic significance, whereas both maternal risk factors and defining infants as SGA had prognostic value in infants delivering preterm, especially less than 34 weeks' gestation. Ponderal index had no significant prognostic value at any gestational age. The data supports the concept that intrauterine growth retardation as defined as an SGA, low birthweight for gestational age infant, may be an inaccurate classification for infants delivering at term, but does have prognostic significance in preterm infants, especially those less than 34 weeks' gestational age.

The accuracy of antenatal fetal echocardiography screening in high- and low-risk patients.

OBJECTIVE: The purpose of this study was to evaluate the accuracy of four-chamber and left ventricular outflow tract views in low-risk patients and comprehensive fetal echocardiographic examinations in high-risk patients to diagnose structural heart disease or thoracic anomalies. STUDY DESIGN: A prospective outcome study of two cohorts was performed; 1136 low-risk patients and 886 high-risk patients were evaluated during a 2-year period. Low-risk patients underwent routine four-chamber and left ventricular outflow tract evaluation whereas high-risk patients had detailed fetal echocardiographic examinations. Accuracy of the ultrasonographic diagnosis was evaluated from neonatal discharge data. RESULTS: Only 2 of 14 patients with congenital heart disease in the low-risk group were correctly identified (sensitivity 14.3%) whereas 10 of 16 patients with congenital heart disease or thoracic anomalies were correctly identified in the high-risk group (sensitivity 62.5%). CONCLUSION: The current study showed poor diagnostic accuracy of the standard four-chamber and left ventricular outflow tract views in low-risk patients for the diagnosis of structural cardiac anomalies. Patients with risk factors for congenital heart disease should be referred for comprehensive fetal echocardiographic examination.

Accurate gestational dating: revisited.

Using first trimester fetal crown-rump length (CRL) measurements as the criterion for gestational dating, rather than menstrual history or neonatal gestational age evaluation after birth, may be a more accurate way of evaluating the accuracy of second or third trimester ultrasonic measurements for gestational age estimation. This hypothesis was tested using two study groups to evaluate the accuracy of second or third trimester ultrasound measurements for the estimation of gestational age. Three hundred twenty normal obstetric patients who had first trimester CRL measurements were evaluated in the first study. Stepwise multiple regression analysis was used to determine the best combination of multiple ultrasonic parameters for calculation of gestational age, using each patient's CRL as his or her own control. The best formula derived from the first set of patients was used in a second set of 138 high-risk patients to determine the accuracy of multiple ultrasonic parameters obtained during the second or third trimester to date gestation accurately. The analysis confirmed the accuracy of multiple ultrasonic parameters for gestational dating and indicated that the use of two parameters (head circumference and femur length) was as accurate as the traditional four-parameter technique.

Intrauterine growth retardation and preterm delivery.

OBJECTIVE: A retrospective study was undertaken to determine if premature infants had a higher incidence of intrauterine growth retardation than term infants did. If premature labor is significantly associated with intrauterine growth retardation, then defining intrauterine growth retardation with a population-specific postnatal birth weight for gestational age curve would underestimate the incidence in preterm infants. STUDY DESIGN: Data for the year 1990 were used to construct a postnatal birth weight for gestational-age curve. This curve was then used to analyze 1991 birth weight data and to determine the incidence of intrauterine growth retardation (< 10th percentile) at each week of gestation. Infants were also classified as having intrauterine growth retardation on the basis of an additional postnatal birth weight for gestational-age curve and two antenatal ultrasonic estimated fetal-weight-for-gestational-age curves. RESULTS: Analysis of the 1991 delivery data indicated that both ultrasonography curves showed a significant decrease in the incidence of intrauterine growth retardation with advancing gestational age, whereas the postnatal curves did not. CONCLUSION: The results give full support to previous reports that suggest intrauterine growth retardation is more common in preterm than in term infants and are consistent with the hypothesis that intrauterine growth retardation is significantly related to premature birth.

Defining altered fetal growth by second-trimester sonography.

A method of predicting birth weight from a single ultrasound examination between 18-28 weeks' gestation was evaluated prospectively in 315 obstetric patients with singleton pregnancies. Estimated fetal weight at the time of the ultrasound examination was used to predict actual birth weight. At delivery, the percent difference between the projected and actual birth weights was then used to define whether an infant was small, appropriate, or large for gestational age. This method appeared to be accurate and showed identical relationships to the presence of abnormal fetal heart rate patterns in growth-retarded infants as did the traditional birth-weight-for-gestational-age method of defining intrauterine growth retardation.

Comparison of dynamic image and pulsed Doppler ultrasonography for the diagnosis of intrauterine growth retardation.

Dynamic image and pulsed Doppler ultrasonography were used to evaluate 104 potentially growth-retarded fetuses. The two techniques were compared, and then used together to predict whether or not the neonate would be growth retarded. Both ultrasonic diagnostic techniques showed good correlation with neonatal outcome, but their combined use improved diagnostic accuracy.

The diagnosis of altered fetal growth.

The antenatal recognition of altered fetal growth should be an important goal for every obstetrician, because significant neonatal complications can be associated with both ends of the spectrum of altered growth. This article discusses the problems related to altered fetal growth, the difficulty in defining and diagnosing it, and some of the methods available for its antenatal diagnosis.

Ultrasonically estimated weight and gestational age. Predictors of neonatal respiratory distress syndrome.

Information from 504 women who had undergone real-time ultrasound examination within 72 hours of childbirth was used to evaluate the relationship between the product of ultrasonically estimated fetal weight (in kilograms) times ultrasonically estimated gestational age (in weeks) and neonatal morbidity and mortality. If this product was greater than 40, there were no neonatal deaths (excluding severe congenital abnormalities); if the product was greater than 80, there were no cases of significant respiratory distress syndrome. These data may prove to be highly useful in the rapid evaluation of preterm labor or other obstetric complications.

Accurate ultrasonic estimation of fetal weight. Prospective analysis of new ultrasonic formulas.

Five new ultrasonic weight formulae incorporating head circumference, fetal femur length, and a correction for oligohydramnios were prospectively analyzed in a group of 198 unselected patients scanned within 72 hours of birth. Comparison with the Shepard formula showed that inclusion of these parameters slightly, but significantly, improved the random error of weight estimation. The best-fit formula was: Log(10) BW = .04355HC + .05394AC - .0008582HC X AC + 1.2594 (FL/AC) - 2.0661.

Accurate ultrasonic estimation of fetal weight. Effect of head shape, growth patterns, and amniotic fluid volume.

Four hundred sixty-four fetuses underwent real time ultrasound examination within 72 hours before birth to evaluate other factors than the weight formula itself that might influence the accuracy of ultrasound weight estimation. The results indicated that fetal sex had no effect on weight estimation accuracy, but that fetal growth patterns, cephalic index, and the amount of amniotic fluid did. The weights of small-for-gestational age infants were significantly overestimated. Infants with oligohydramnios and low cephalic indexes were significantly underestimated by the ultrasonic weight formula. The weights of infants with high cephalic indexes were slightly overestimated and infants that were large-for-gestational age were slightly underestimated.

The design and implementation of a computer-based ultrasound data system.

A detailed description of the development of a computer-based ultrasound data system is presented to provide the background for those physicians interested in developing or using such a system. The system was found to be highly useful for acquisition and organization of ultrasound data, and proved to be an aid both teaching and patient care.