ABSTRACT
Objective:To investigate the performance of chromosome karyotype, chromosomal microarray analysis (CMA) and fluorescence in situ hybridization (FISH) in prenatal diagnosis of true fetal chromosome mosaicism. Methods:This retrospective study enrolled 40 women with true fetal chromosome mosaicism from 4 071 singleton pregnant women who were indicated for and underwent amniocentesis or/and cordocentesis in the the First Affiliated Hospital of Sun Yat-sen University from April 2018 to August 2021. The results of chromosome karyotyping, CMA and FISH, the types of chromosomal mosaicism, mosaicism ratio and pregnancy outcomes were analyzed using Chi-square test. Results:(1) The detection rate of true fetal mosaicism was 0.98% (40/4 071). (2) Sex chromosome mosaicism accounted for 42.5% (17/40). Other chromosomal mosaicism involved chromosomes 21, 22, 18, 16, 7, 12, 15, 17 and 20, as well as balanced chromosomal translocation. (3) The detection rate of true fetal mosaicism by chromosome karyotyping was 77.4% (24/31) from amniotic fluid samples and 10/19 from umbilical cord blood samples, while that data by CMA was 76.7% (23/30) and 7/11,respectively. (4) Of the 40 pregnant women with fetal chromosome mosaicism, FISH test was performed on 20 cases (14 cases were verified with both amniotic fluid and umbilical cord blood samples, five with amniotic fluid samples and one with umbilical cord blood sample), and all of the diagnosis of mosaicism were confirmed. For those with mosaicism ratio <30%, the detection rate by FISH was higher than that by CMA among amniotic fluid samples [14/19 vs 43.5% (10/23), χ2=3.88, P=0.049]. (5) Among the 40 pregnant women, five were lost to follow-up; 18 chose to terminate the pregnancy; and 17 continued the pregnancy to delivery. No abnormalities in mental or physical development were reported in the 17 neonates after birth or during on-line follow-up between 6 to 24 months old. Of the 14 pregnant women with mosaicism ratio <30% which confirmed by FISH, eight chose to continue the pregnancy, and no abnormalities in mental development or growth were found in the neonates. Conclusions:In prenatal diagnosis of true fetal choromosome mosaicism, the incidence of sex chromosome mosaicism is the highest. FISH may improve the prenatal diagnosis rate of mosaicism and is more accurate in determining the mosaicism ratio. The combination of FISH, CMA and chromosome karyotyping would significantly improve the detection rate of chromosomal mosaicism and assess the mosaicism ratio more accurately, which is of great value in clinical consultation and evaluation of fetal prognosis.
ABSTRACT
Objective:To analyze the effects of selective feticide by radiofrequency ablation (RFA) and the risk factors for adverse pregnancy outcomes in twins complicated by selective intrauterine growth restriction (sIUGR) and evaluate the neurodevelopment in live births during a short-term follow-up.Methods:This study retrospectively enrolled 75 twins with sIUGR who underwent RFA for selective feticide and were delivered in the First Affiliated Hospital of Sun Yat-sen University between January 1, 2017 and March 31, 2022. According to the gestational age at the procedure, they were divided into three groups including 16-19 +6 weeks of gestation (Group A, n=16), 20-23 +6 weeks of gestation (Group B, n=44) and ≥24 weeks of gestation (Group C, n=15). They were also grouped according to the presence or absence of twin-twin transfusion syndrome (TTTS): sIUGR with TTTS group ( n=36) and isolated sIUGR group ( n=39). The 39 cases in the isolated sIUGR group were further divided into three groups according to the Doppler flow in the smaller co-twin: type Ⅰ ( n=3), type Ⅱ ( n=27) and type Ⅲ ( n=9). According to pregnancy outcomes, the 75 cases were divided into adverse pregnancy outcome group ( n=49) and non-adverse pregnancy outcome group ( n=26). Statistical analysis was performed using two independent sample t-test, one-way analysis of variance and LSD test, nonparametric test and Nemenyi test, as well as Chi-square test and Fisher's exact test to compare the difference in clinical characteristics and perinatal outcomes among groups. Kaplan-Meier survival curves and Log-rank test were used to analyze the duration of pregnancy after the procedure. Univariate logistic regression analysis was used to identify the risk factors for adverse pregnancy outcomes. Results:(1) The gestational age at the time of procedure was (21.9±2.3) weeks (16.6-26.0 weeks) for all cases. The intertwin estimated fetal weight discordance (ΔEFW) was less and the duration of RFA was shorter in group A than in group B or C [(27.8±8.4)% vs (36.2±12.0)% and (39.8±15.5)%; 7 min (5-14 min) vs 10 min (5-16 min) and 12 min (8-18 min); LSD test or Nemenyi test, P<0.017]. The incidence of TTTS was higher in group A than in group B or C [12/16 vs 43% (19/44) and 5/15; Bonferroni correction, P<0.017]. There was no significant difference in the incidence of premature rupture of membrane, spontaneous abortion, fetal demise, premature delivery and gestational age at delivery between Group A, B and C (all P>0.05). (2) Compared with the isolated sIUGR group, the sIUGR with TTTS group showed less ΔEFW [(29.6±11.4)% vs (40.1±11.8)%, t=3.88, P<0.001], higher incidence of premature rupture of membrane [47% (17/36) vs 21% (8/39), χ2=6.01, P=0.014], lower rate of live births [69% (25/36) vs 95%(37/39), χ2=8.45, P=0.004] and earlier delivery [34.1 weeks (26.7-40.7 weeks) vs 38.0 weeks (29.3-40.0 weeks), Z=311.50, P=0.018]. (3) There was no significant difference in the incidence of premature rupture of membrane, live birth rate or 30-day survival rate among the sIUGR type Ⅰ, Ⅱ and Ⅲ groups (all P>0.05). (4) sIUGR complicated by TTTS was a risk factor for adverse pregnancy outcomes of the co-twin after the procedure ( OR=3.94, 95% CI: 1.40-11.10, P=0.010). (5) Thirteen co-twins presented with cardiac enlargement, myocardial hypertrophy or/and tricuspid regurgitation in routine ultrasound scans before the procedure and nine of them had TTTS. Among them, eight live births were followed up for one month to 4.5 years of age and no abnormality in cardiac function was reported. (6) There were overall 62 live births. Apart from two cases of neonatal death and four lost to follow-up, the other 56 cases were followed up to one month to 5 years of age and two premature infants showed gross motor retardation. Conclusions:The gestational age at RFA has no significant impact on pregnancy outcomes, while sIUGR complicated by TTTS may increase the risk of adverse outcomes after the procedure. After RFA, the overall survival rate of the co-twin in pregnancies with sIUGR is high and no severe neurodevelopmental abnormalities has been found during a short-term follow-up.
ABSTRACT
Objective:To investigate the prenatal genetic features and the factors influencing the prognosis of twin reversed arterial perfusion sequence (TRAPS) in monochorionic twin pregnancies.Methods:A total of 99 cases diagnosed with TRAPS by prenatal ultrasound in the First Affiliated Hospital of Sun Yat-sen University from July 1, 2007, to December 31, 2021, were included retrospectively. The prenatal genetic features of acardiac and pump twins were analyzed. Eighty-nine cases were followed up and divided into two groups: the expectation group ( n=45) and the intrauterine intervention group (all underwent radiofrequency ablation, n=44) and the pregnancy outcomes were compared between the two groups. After excluding eight cases without complete ultrasound data, the expectation group was further divided into two subgroups: the pump fetus survival ( n=28) and the pump fetus death groups ( n=9), and the survival subgroup was divided into the spontaneous arrest group ( n=16) and coexistence group ( n=12) according to whether or not the blood flow stopped spontaneously.The relationship between ultrasonic indexes and pregnancy outcome was compared between the groups. Chi-square test (or Fisher's exact test), univariate logistic regression analysis and receiver operating characteristic (ROC) curve were used to analyze the relationship between the estimated acardiac to pump twin weight ratio (A/P Wt) and the pregnancy outcome of the pump twin in the expectation group. Results:(1) The median gestational age at diagnosis of the 99 TRAPS cases was 16.4 weeks (13.3- 21.3 weeks) and 32% (32/99) were diagnosed in the first trimester. Most of the cases were monochorionic diamniotic pregnancies (72/99, 73%). The survival rate of the pump twins was 71% (63/89). (2) Chromosome karyotyping and/or chromosomal microarray analysis was performed in 19 acardiac twins and 82 pump twins. The detection rate of genetic abnormalities in the acardiac twins was higher than that in the pump twins [4/19 vs 5% (4/82), Fisher's exact test, P=0.039]. Chromosomal microarray analysis was performed in 54 pump twins with normal karyotypes and the results showed three (6%) with genetic abnormalities. (3) In the expectation group, the area under ROC curve for the prenatal A/P Wt were 0.913 in predicting pump twin death and 0.807 in predicting spontaneous cessation of blood flow in the cardiac twin, and the cut-off values were 0.24 (sensitivity: 88.9%, specificity: 96.4%) and 0.11 (sensitivity: 75.0%, specificity: 81.3%), respectively. The survival rate of pump twins with abnormal cardiac function after intrauterine intervention was higher than that of the expectant group [72% (18/25) vs 3/11, Fisher's exact test, P=0.025]. Conclusions:TRAPS can be diagnosed in the first trimester and commonly occur in monochorionic diamniotic pregnancies. The detection rate of genetic abnormalities in the acardiac twins is higher than that in the pump twins. Prenatal A/P Wt>0.24 indicates the death of the pump twin and prenatal A/P Wt≤0.11 suggests a high possibility of spontaneous cessation of blood flow in the acardiac twin. Radiofrequency ablation is an effective method for improving the prognosis of the pump twin with cardiac dysfunction.