Doppler assessment of fetal aortic isthmus flow in twin

OBJECTIVE: The purpose of this study was to investigate the aortic isthmus (AoI) flow difference between larger fetus and smaller fetus of twin; and to evaluate the predictive value of early diagnosis of hemodynamic change in twin growth. METHODS: This prospective study on 49 pairs of twin fetuses was performed to obtain AoI blood flow data. Cases with structural or chromosomal abnormalities and co-twin death were excluded. The interval from examination to delivery was within 4 weeks and 3 cases over 4 weeks interval were re-examined. Assessment of fetal AoI Doppler parameters were peak systolic velocity (PSV), end-diastolic velocity, times-averaged maximum velocities, pulsatility index (PI), and resistance index (RI). According to the direction of the diastolic flow in the AoI, antegrade and retrograde flow were made and was used to analyze the perinatal outcomes of each fetus. The predictive value of AoI Doppler parameters in predicting fetal growth was obtained by using ANOVA and logistic regression analysis of quantitative variables in each fetus of twins. RESULTS: There were significant differences in the gestational weeks at delivery, birth weight and the incidence of growth discordance over 20% or more between monochorionic twin and dichorionic twin. The AoI PI and RI were significantly higher in smaller fetus than in larger regardless of chorionicity. Retrograde flow was noted in 8 of 98 cases (8.2%) and the only one case was of the larger fetus and the others were smaller fetuses of twin. Significant correlations were found between the AoI PI and birthweight (P=0.018) and between the PSV and growth discordance (P=0.032). In monochorionic twin, linear correlation was shown between the AoI PI and birthweight (P=0.004) and between AoI PI and growth discordance (P=0.031). Also, the meaningful correlation between the PSV and birthweight (P=0.036) was found by using logistic regression analyses. CONCLUSION: On the basis of our observation, AoI PI has revealed their hemodynamic status and this result may improve the understanding of growth patterns in twins.

The Hemodynamic Change of Doppler Flow Velocimetry to Developing of Twin Growth Discordance in Relation to Placental Chorionisity, Placental Weight and Umbilical Cord Insertion / 대한산부인과학회잡지

OBJECTIVE: To evaluate hemodynamic change in growth discordant twins using a ratio of middle cerebral artery/umbilical artery resistance index and to assess the relationship between Doppler hemodynamic and the influence of placental chorionisity and umbilical cord insertion. METHODS: 118 live born twin pairs whose birthweight discordance below or above 20% between March 2000 and March 2002 were included in our study. And we divided the two groups in which above 20% of growth discordance (GD) group was GD and below 20% of GD group was control. Chorionisity and umbilical cord insertion in all study subjects within 24 hours after delivery were investigated. And then we classified to monochorionic (MONO), and dichorionic (DI) placenta and the type of insertion of umbilical cord were also classified central, marginal and velamentous type. 56 of twin pairs were performed 153 Doppler flow velocimetry between smaller and larger fetus prenatally. Resistance index (RI) of middle cerebral artery and umbilical artery in each fetus were measured and standardized as a ratio of middle cerebral artery/umbilical artery (MCA/UmA). ANOVA, Mann-Whitney U test, and chi-square test, were performed and p<0.05 was considered as statistically significant. RESULTS: Mean birthweight in monochorionic twins had lighter than those of dichorionic twins (p<0.01). The mean growth discordant ratios were 14.1% in monochorionic twin and 12.1% in dichorionic twins. In monochorionic twin, the smaller fetus in GD group showed lower value of MCA/UmA RI ratio than those of the larger fetus, significantly (1.09 vs. 1.28 p<0.05). And in monochorionic twins, the smaller fetus in GD group showed lower value of MCA/UmA RI ratio than the smaller fetus in control group, significantly (1.09 vs. 1.27 p<0.05). The placental weight in dichorionic twin was correlated the birthweight in infants in GD group, positively. Monochorionic twins in GD group had a significantly higher incidence of peripheral cord insertion than those of dichorionic twins in GD group (50.0% vs. 35.7% p<0.01). But dichorionic twins had a significantly higher incidence of central cord insertion than those of monochorionic twins in control group (69.2 vs. 57.4 p<0.05). CONCLUSION: The higher middle cerebral artery blood flows in smaller fetuses of monochorionic twins proved to be circulatory redistribution of the fetus in inadequate intrauterine condition. And these change of middle cerebral blood flow might be understood the part of mechanisms fetal growth and adaptation. Placental weight, number and umbilical cord insertion were also important factors which affected to develop the growth discordance of twin pregnancy.

The Hemodynamic Change of Doppler Flow Velocimetry to Developing of Twin Growth Discordance in Relation to Placental Chorionisity, Placental Weight and Umbilical Cord Insertion / 대한산부인과학회잡지

OBJECTIVE: To evaluate hemodynamic change in growth discordant twins using a ratio of middle cerebral artery/umbilical artery resistance index and to assess the relationship between Doppler hemodynamic and the influence of placental chorionisity and umbilical cord insertion. METHODS: 118 live born twin pairs whose birthweight discordance below or above 20% between March 2000 and March 2002 were included in our study. And we divided the two groups in which above 20% of growth discordance (GD) group was GD and below 20% of GD group was control. Chorionisity and umbilical cord insertion in all study subjects within 24 hours after delivery were investigated. And then we classified to monochorionic (MONO), and dichorionic (DI) placenta and the type of insertion of umbilical cord were also classified central, marginal and velamentous type. 56 of twin pairs were performed 153 Doppler flow velocimetry between smaller and larger fetus prenatally. Resistance index (RI) of middle cerebral artery and umbilical artery in each fetus were measured and standardized as a ratio of middle cerebral artery/umbilical artery (MCA/UmA). ANOVA, Mann-Whitney U test, and chi-square test, were performed and p<0.05 was considered as statistically significant. RESULTS: Mean birthweight in monochorionic twins had lighter than those of dichorionic twins (p<0.01). The mean growth discordant ratios were 14.1% in monochorionic twin and 12.1% in dichorionic twins. In monochorionic twin, the smaller fetus in GD group showed lower value of MCA/UmA RI ratio than those of the larger fetus, significantly (1.09 vs. 1.28 p<0.05). And in monochorionic twins, the smaller fetus in GD group showed lower value of MCA/UmA RI ratio than the smaller fetus in control group, significantly (1.09 vs. 1.27 p<0.05). The placental weight in dichorionic twin was correlated the birthweight in infants in GD group, positively. Monochorionic twins in GD group had a significantly higher incidence of peripheral cord insertion than those of dichorionic twins in GD group (50.0% vs. 35.7% p<0.01). But dichorionic twins had a significantly higher incidence of central cord insertion than those of monochorionic twins in control group (69.2 vs. 57.4 p<0.05). CONCLUSION: The higher middle cerebral artery blood flows in smaller fetuses of monochorionic twins proved to be circulatory redistribution of the fetus in inadequate intrauterine condition. And these change of middle cerebral blood flow might be understood the part of mechanisms fetal growth and adaptation. Placental weight, number and umbilical cord insertion were also important factors which affected to develop the growth discordance of twin pregnancy.

Intrauterine Growth Curve of Twins on the Basis of Gestational Age / 대한산부인과학회잡지

OBJECTIVE: In order to investigate more accurate patterns of intrauterine growth in twin fetuses, we constructed the twin-specific growth curve based on gestational age in live-born non-anomalous infants. METHODS: 563 twin pairs, 1,126 infants delivered between January 1994 and October 1999 were comprised our study population. The newborns were grouped according to gestational age and the median, 10th, 50th, and 90th percentile birth weight for each gestational week were calculated. Curves were plotted for the general population and for each gender and parity and compared with previously reported singleton's growth curve. RESULTS: After 32 weeks gestation, birth weight of twins falls below that of singleton, so that by 38 weeks the 50th percentile for twins falls below the singleton 10th percentile. This difference was also present among all subgroups of twins, such as gender and parity. And the mean birth weight in male twin infant was heavier than in female twin infant throughout all gestational week. CONCLUSION: The pattern of growth in twin infants differed from those of singleton. We recommend twin-specific growth curve for clinical use in the management of twin gestations.