The cerebroplacental Doppler ratio and neonatal outcome in diamnionic monochorionic and dichorionic twins.

OBJECTIVE: Neonatal outcome in twins was studied in relation to the cerebroplacental ratio (CPR). METHODS: Seventy-five infants from twin pregnancies with fetal Doppler data obtained within 3 weeks of delivery were candidates for study (23 infants from diamnionic monochorionic and 52 infants from diamnionic dichorionic twin pregnancies). Multivariate regression analyses were expanded to include 114 twin infants (34 diamnionic monochorionic and 80 diamnionic dichorionic twins). Patients with twin transfusion syndrome were excluded from analysis in the monochorionic group. Targeted ultrasound examination with biometry was performed, and Doppler resistance index (RI) of the umbilical artery (UA) and the middle cerebral artery (MCA) were obtained, and the CPR, a measure of blood flow redistribution, was calculated. Outcome variables included major complications, growth restriction, days of ventilator and oxygen use, days in the neonatal intensive care unit and length of stay. RESULTS: The CPR was correlated more highly with adverse outcomes such as birth weight, special-care nursery days and length of stay than were the UA RI or the MCA RI. The CPR was significantly lower in monochorionic compared with dichorionic twins (1.12 vs. 1.27, p = 0.01). Multivariate regression analyses conducted separately on each twin group also demonstrated that CPR was superior to UA RI and MCA RI in predicting length of stay and restricted growth. Among the Doppler variables, the CPR showed the highest sensitivity for growth restriction (67%). CONCLUSION: In twins, CPR was superior to UA RI and MCA RI in predicting adverse neonatal events.

Diamnionic monochorionic twin gestations: an overview.

Monochorionic (MC) twins account for about 20-30% of all twins, but contribute disproportionately to mortality, intrauterine growth restriction, and preterm delivery compared with dichorionic (DC) twins. This higher mortality in MC twins is likely due to the effects of placental morphologic characteristics, which include complex vascular communications between the twins associated with twin-twin transfusion syndrome (TTTS), and the tendency for the common placenta to be shared either symmetrically or asymmetrically. In assessment of clinical outcomes for TTTS, artery to vein anastomoses in the absence of artery to artery or vein to vein, especially if present with placental asymmetry, carry the worse prognosis. Chorion status in twins forms the basis for clinical risk assessment and can be determined by 7 menstrual weeks using transvaginal sonography. The variable results reported in the literature for intertwin umbilical artery Doppler findings in MC twins may be explained by differences between sonographic and clinical criteria (including differential hemoglobin concentrations) reported by various investigators. Antenatal fetal Doppler assessment of the umbilical artery and cerebral arteries can help distinguish between TTTS and placental insufficiency in MC twins. Significant restriction of fetal growth occurs in about 25% of multiple gestations, accounting for about 17% of all growth-retarded infants. Redistribution of fetal blood (brain-sparing effect), as determined by Doppler interrogation of fetal cerebral and umbilical arteries, occurs more commonly in MC twins compared to DC twins and in growth-restricted MC twins compared to nongrowth-restricted MC twins. Overall, the prognosis is poorer for the donor twins in TTTS and there is a greater prenatal death rate for the donor (18-35%), and a higher overall survival rate for recipients following fetoscopic laser treatment. Finally, the clinical and sonographic findings suggest that the polyhydramnios/oligohydramnios sequence seen in MC twins likely represents a spectrum strongly linked to placental variables.

Antenatal ultrasound and fetal Doppler. Diagnosis and outcome in intrauterine growth retardation.

Advances in ultrasonographic biometry and fetal Doppler technology enhance our ability to detect the presence of fetal growth retardation, expand our understanding of its pathophysiology, and improve the ability to predict certain outcome parameters. Further refinement of these methods will allow better definition of IUGR as well as a means to more accurately direct perinatal resources. As causes of fetal growth retardation become more precisely defined, improvements in outcome are likely for certain subsets of those populations.

Is it time to reassess the risk for the growth-retarded fetus with normal Doppler velocimetry of the umbilical artery?

OBJECTIVE: Previous studies demonstrate an association between abnormal umbilical artery Doppler velocimetry and the birth of a small-for-gestational-age infant and between abnormal result and adverse neonatal outcome. The hypothesis is that preterm growth-retarded infants with normal antenatal velocimetry have outcomes similar to other preterm infants, whereas preterm small-for-gestational-age infants with abnormal Doppler results define a subgroup with increased morbidity. STUDY DESIGN: For 100 live-born infants, at risk for fetal growth retardation and undergoing antenatal Doppler and targeted ultrasonographic examinations, we assessed a number of complete neonatal outcome parameters. RESULTS: Ten neonatal deaths occurred in the study population, seven with abnormal Doppler results and three with normal Doppler results. Of the 90 surviving infants, gestational age at delivery was not different between the Doppler normal and abnormal neonates, whereas birth weight (1714 gm vs 1379 gm) was higher in the Doppler normal group (p = 0.006). The presence of intraventricular hemorrhage (20% vs 6%) was higher in the abnormal group (p = 0.05). Abnormal Doppler results defined an infant group destined for prolonged hospitalization, mean intensive care days (21 vs 9), and special care nursery days (25 vs 9). Thirty-eight percent of small-for-gestational-age babies had a normal Doppler result. Analysis of variance indicated small-for-gestational-age infants with abnormal Doppler results (n = 20) had a mean intensive care unit stay of 31 days, significantly different (p = 0.005) from small-for-gestational-age infants with normal Doppler results (n = 14), non-small-for-gestational-age infants with abnormal results (n = 21), and non-small-for-gestational-age infants with normal results (n = 35) whose mean intensive care unit stays were 14, 12, and 7 days, respectively. Gestational age at delivery (33.0 weeks) was not different among these groupings, not accounting for the observed differences. CONCLUSION: Normal antenatal velocimetry defines a distinct subgroup of preterm small-for-gestational-age infants at less risk for prolonged hospitalization compared with those with abnormal velocimetry.

Survival and follow-up of infants born at 23 to 26 weeks of gestational age: effects of surfactant therapy.

Little information is available regarding the effect of surfactant on outcome for infants born at or before 26 weeks of gestation. We addressed this issue by reviewing records of 310 infants born at gestational ages of 23 through 26 weeks who were admitted to our nursery from 1986, when surfactant was introduced, through 1990. Surfactant was administered to 154 infants (5 during a single-dose prevention study, 25 during a multiple-dose prevention study, 124 while receiving a Food and Drug Administration treatment investigational new drug); 156 infants were not treated with surfactant. Seventy-three percent of the treated infants survived, compared with 55% of the nontreated infants. Increased survival occurred at all gestational ages between 23 and 26 weeks but were greatest in infants born at 23 and 24 weeks. At follow-up, no differences in neurologic outcome were detected between surfactant-treated and nontreated infants. We conclude that surfactant use in extremely premature infants improves survival rates without increasing the proportion of impaired survivors.

Evaluation of fetal cardiac arrhythmias. Ultrasound findings and neonatal outcome.

During a four-year period, 3,882 fetal diagnostic ultrasounds were performed and 162 patients (4% of all patients scanned) were referred to our perinatal center for evaluation of fetal cardiac arrhythmia. Fetal echocardiography subsequently revealed an arrhythmia in 80 (49%) of these patients. The rhythm disturbances noted were premature atrial or ventricular contractions (n = 65, 81%), tachyarrhythmia (n = 8, 10%), and bradyarrhythmia (n = 7, 9%). Three of the bradycardic fetuses evaluated had complete heart block associated with anatomic abnormalities. In seven tachycardic fetuses, the finding of fetal compromise was followed by intervention. The majority of fetuses with cardiac rhythm disturbance will have premature atrial or ventricular contractions and will have normal echocardiographic evaluation and neonatal outcome. Sustained tachyarrhythmias and bradyarrhythmias are more likely to be associated with fetal morbidity. Based upon the findings of this study and others, we propose a scheme for follow-up of the fetus referred with an irregular cardiac rhythm.

Is pulsed Doppler velocimetry useful in the management of multiple-gestation pregnancies?

Few studies have addressed the significance of umbilical artery pulsed Doppler velocimetry in multiple gestation. Level II ultrasonography and pulsed Doppler studies were performed in 94 twin pairs and seven sets of triplets, which yielded data on 207 fetuses. A systolic/diastolic ratio was calculated for each fetus; abnormal pulsed Doppler velocimetry showed high correlation with adverse pregnancy events. Those with abnormal Doppler findings tended to be born 3 to 4 weeks earlier and to exhibit a greater number of stillbirths and structural malformations, as well as greater morbidity, when compared with fetuses without abnormal Doppler results. Fifteen of 17 infants with abnormal antenatal waveforms suffered serious morbidity. Seven were small for gestational age, and two were borderline for small for gestational age. An additional five infants with abnormal waveforms were appropriate for gestational age but were either recipient or donor in the twin transfusion syndrome. Eleven fetuses with this syndrome are described. Donor twins tended to be severely small for gestational age, with 7 of the 11 infants showing elevated systolic/diastolic ratios. Amniotic fluid volume tended to be diminished in the donor's sac but normal or increased in the recipient's sac. The observations in the study correlate with suspected physiologic changes of this syndrome. Because present findings suggest that fetuses with abnormal velocimetry suffer increased morbidity and mortality, a more rational method of management that uses Doppler data is suggested for multiple gestations.

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.

Antenatal prediction of women at increased risk for infants with low birth weight. A discriminant analysis of maternal characteristics known at 24 weeks.

Prenatal factors known to be associated with delivery of an infant with low birth weight (LBW) were studied in 165 women who were delivered of infants of 25,000 gm or less, as well as 154 women who were delivered of term infants with normal birth weights (greater than 2,500 gm). Data included information related to th clinical course of the pregnancy through 24 weeks' gestation. Of 25 characteristics measured prenatally, 10 variables were identified with indicated differences between the LBW and normal birth weight groups sufficient to make them suitable for a discriminant analysis. Following further analysis and attribute reduction, eight variables were selected as the final set of discriminating attributes. These are: maternal age, height, and weight, the patients's perception of her own parental treatment as a child, presence of uterine anomalies, bleeding during pregnancy, suspected multiple gestation, and number of previous pregnancies ending with a gestational age of 13 through 36 weeks. On the basis of coefficients derived for each of these variables, an equation was developed to derive a discriminant score for each patient. With the use of such equations, 73.5% of the known cases were correctly classified into groups with low and high birth weight. A similar high correct classification of cases was made when suspected multiple gestation was excluded as a variable.

FHR variability and other heart rate observations during second stage labor.

Seventy-four fetal heart rate (FHR) records that were continued to vaginal delivery were selected for study from more than 2000 intrapartum FHR tracings. Thirty-six of the births were associated with neonatal depression and Apgar scores of 3 or less and/or 6 or less at 1 and 5 minutes, respectively; 38 patients exhibited normal Apgar scores (7 and 10 at 1 and 5 minutes, respectively). Twenty minutes of heart rate activity immediately prior to birth was the basis of analysis. All categories of loss of short-term beat-to-beat variability (BBV), both baseline and with decelerations, were observed more frequently in the group with low Apgar scores (P less than .001). In assessing variability, duration of observed loss of BBV appears to be an extremely critical factor. If BBV was lost 50% or less of observation time, a wide range of Apgar scores was observed. When more than 50% of the record showed loss of BBV, the number of depressed neonates was relatively high. Bradycardia (heart rate of less than 120 beats per minute) was present frequently in the records of the normal group. The number of variable decelerations and the amount of uterine activity were relatively high during second stage labor; a similar frequency was noted in both groups. Decelerations were nearly uniformly associated with uterine contractions in both groups, and accelerations were also noted in both groups. Uniform decelerations (late) were also present in both groups, with a greater frequency in the group with lower Apgar scores, but there were no distinguishing characteristics noted.