Pregnancy outcomes with increased nuchal translucency after routine Down syndrome screening.

OBJECTIVES: The purpose of this study was to evaluate the outcomes of pregnancies with nuchal translucency greater or equal to 3 mm for routine first trimester screening in unselected populations. METHODS: A total of 2980 pregnant women for first trimester ultrasonography were routinely offered crown-rump length (CRL) and nuchal translucency (NT) for screening for Down syndrome between 11 and 14 weeks' gestation. A complete follow-up was obtained in all cases by a review of medical records. RESULTS: Using a cut-off value of 3 mm, the prevalence of increased fetal NT was 0.7% (n=22). Among the 22 cases, there were five (22.7%) chromosomal abnormalities. Of the 17 chromosomally normal pregnancies, four resulted in fetal demise (spontaneous abortion, intrauterine death or termination of pregnancy due to fetal abnormalities). The remaining 13 pregnancies resulted in live births, including one gestational hypertension and one preterm delivery, respectively. The total incidence of an adverse outcome in the group of increased fetal NT was 45.5%. CONCLUSIONS: In a routine population with first-trimester ultrasonography, fetal NT measuring greater than or equal to 3 mm was associated with a poor pregnancy outcome with not only chromosomal abnormalities and congenital cardiac diseases, but also poor maternal and fetal health or adverse pregnancy outcomes. In addition, this study also demonstrated the necessity for fetal assessment and follow-up in cases where the fetal NT is increased in the first trimester.     

Quality assurance of nuchal translucency for prenatal fetal Down syndrome screening

Objective: To assess the quality of nuchal translucency, (NT) measurements were performed at four public institutions performing routine first trimester combined prenatal screening for Down syndrome. Methods: The median of the NT-MoM distribution and standard deviation (SD) of the log₁₀ NT-MoM were determined. Sonographers and screening centres distributions were assessed for measures of central tendency (median) and dispersion (log₁₀ SD). Cumulative Sum (CUSUM) charts were created to assess whether screening centres and individual sonographers who had performed at least 30 NT measurements exhibited any systematic bias by checking whether their CUSUM scores exceeded predefined upper and lower control limits. Results: Of the 36 sonographers, only 67% (n?=?24) had performed 30 or more scans. The median NT-MOM at each screening centre ranged from 1.02 to 1.09. Screening centre standard deviations ranged from 0.073 to 0.099. CUSUM charts indicated that only one screening centre remained within the predefined control limits throughout the assessment period. Analysis of variance indicated that a statistically significant difference existed between the log NT-MoM distributions of the individual sonographers (F?=?10.7; p <0.0001). Inspection of the individual sonographer CUSUM charts indicated that 11 (45%) of the 24, with more than 30 NT measurements were either under or over measuring the NT. Conclusion: Prospective monitoring and feedback of quality assurance assessment results of sonographers and screening centres should be routinely reported as both are responsible, if equity of screening performance is to be maintained.     

Down syndrome screening in multiple pregnancies by nuchal translucency measurement

Various non-invasive screening methods for Down syndrome have been introduced in clinical practice during the last two decades. Specific problems were encountered when these methods were applied for multiple pregnancies (twins and high-order multiples). The aim of the current review is to explore these issues and propose an adjusted methodological approach for this highly selected population. Overall, more women with twin pregnancies (mainly those who conceived via assisted reproduction) are found to be false-positive for Down syndrome. This is because the standard screening algorithms include maternal age. In addition, mid-trimester maternal serum screening is associated with a higher false-positive rate, secondary to changes in the fetoplacental endocrinologic metabolism in assisted reproduction pregnancies. Therefore, in multiple pregnancies, mid-trimester maternal serum screening is of limited clinical value. In those pregnancies, screening for Down syndrome by means of nuchal translucency measurements at 10-14 weeks is associated with a lower false-positive rate than mid-trimester serum screening. Nuchal translucency measurement is among the best available and most efficient screening methods for multiple pregnancies. This method for screening enables us to specifically identify those fetuses at high risk of Down syndrome and other anomalies and thus contribute for a better outcome. In addition, it should be systematically performed before any fetal reduction in high-order multiples is planned.     

Fetal nuchal translucency and skinfold to screen for fetal aneuploidy

Nuchal translucency (NT) is defined as the accumulation of subcutaneous fluid in the nuchal region of the fetus at 11-14 weeks. Its measurement in order to modify the previous background risk has been proved to be able to detect around 70% of trisomy 21 pregnancies (for a 5% fixed positive rate). When affected fetuses dying before 20 weeks are excluded, detection rate may decrease to 60%. Given that appropriate training of sonographers and adherence to a standard technique for the measurement of NT is of paramount importance to reduce variability, the Fetal Medicine Foundation has established a certification process. Fetal nuchal edema displayed at 15-20 weeks was described as enlarged nuchal skinfold, and is a less sensitive but more specific marker than nuchal translucency. Webbing of the neck in infants with trisomy 21 may be envisaged as the remainder of nuchal distension.     

Comparison and integration of first trimester fetal nuchal translucency and second trimester maternal serum screening for fetal Down syndrome

BACKGROUND: It is uncertain whether first trimester nuchal translucency (NT) is more effective than the well-established second trimester serum screening for fetal Down syndrome or whether their combination works best. We report data from a large multicentre non-interventional trial in which all subjects underwent both first and second trimester screening. METHODS: All women who attended the obstetric clinic before 15 weeks' gestation were recruited. An ultrasound examination was performed at 10 to 14 weeks to measure the NT. The nuchal measurements were not acted upon unless the fetus showed gross features of hydrops fetalis. All women had serum alpha-fetoprotein (AFP) and human chorionic gonadotrophin (hCG) assay at 15 to 20 weeks. The Down syndrome risk assigned by serum screening was disclosed and amniocentesis was offered if this assigned risk was >or=1:250 or if the women were 35 years and older. The efficacy of different combinations of screening markers was compared. RESULTS: Between January 1997 and August 2000, 17 590 women were recruited (19% >or=35 years old). After excluding subjects who miscarried, defaulted the serum test and other reasons, 16 237 pregnancies were analysed. Of these, 35 pregnancies were affected by Down syndrome (2.2 cases per 1000 pregnancies). At a false-positive rate of 5%, the detection rate of Down syndrome by NT alone, NT and age, serum hCG, AFP and age, and NT, hCG, AFP and age were 61%, 69%, 73% and 86%, respectively. CONCLUSION: Integration of NT and second trimester serum AFP and hCG assay yielded the best screening efficacy for Down syndrome.     

Predictive value of increased nuchal translucency as a screening test for the detection of fetal chromosomal abnormalities

Objective.?The study aimed to estimate the incidence of increased nuchal translucency in the first trimester ultrasound scan results (cut-off limit 2.5 mm) and to evaluate the predictive value of increased nuchal translucency as a screening test for the detection of fetal chromosomal abnormalities.

Methods.?We used the ultrasound scan results of nuchal translucency evaluation and the results of chromosomal analysis of the invasive prenatal control performed as a result of increased nuchal translucency.

Results.?We collected 2183 nuchal translucency ultrasound scans in which we detected 21 embryos with a pathologic value (0.96%). We collected the data of 168 cases of invasive prenatal control due to increased nuchal translucency from which 122 cases were found. A total of 122 cases of pregnant women undergone an invasive prenatal diagnostic method due to increased nuchal translucency, of which 11 fetuses were found with trisomy 21 (Down syndrome) (9%), 3 fetuses with trisomy 13 (Patau syndrome) (2.45%), 3 fetuses with monosomy 45XO (Turner syndrome) (2.45%) and 1 fetus with translocation (0.8%).

Conclusions.?The positive predictive value of the increased fetal nuchal translucency as a screening test for the detection of fetal chromosomal abnormalities based on the results of the chromosomal-genetic analysis of the invasive prenatal diagnostic procedures is 14.8%.     

早孕期颈项透明层增厚伴或不伴颈部淋巴水囊瘤胎儿的产前诊断结果及妊娠结局分析

目的比较早孕期颈项透明层(nuchal translucency,NT)≥5 mm伴或不伴颈部淋巴水囊瘤(cystic hygroma,CH)胎儿的产前诊断结果及妊娠结局。方法回顾性分析2017年7月至2020年12月在广州市妇女儿童医疗中心就诊的NT≥5 mm且接受介入性产前诊断的131例胎儿资料,按照囊肿内是否存在分隔将所有病例分为NT增厚不伴CH组(囊肿内未发现分隔,74例)和NT增厚伴CH组(囊肿内可见分隔,57例)。比较2组胎儿遗传学检测结果、胎儿超声结构畸形发生率以及出生后健康存活率。采用χ²检验、Fisher精确概率法或非参数检验进行统计学分析。结果NT增厚不伴CH组与NT增厚伴CH组胎儿遗传学检测结果异常发生率[67.6%(50/74)与61.4%(35/57),χ²=0.54,P=0.464]、超声结构异常发生率[21.6%(16/74)与33.3%(19/57),χ²=2.26,P=0.133]、健康存活率(12/14与3/8,Fisher精确概率法,P=0.052)比较,差异均无统计学意义。结论NT增厚伴或不伴CH胎儿,虽然两者疾病谱不同,但合并染色体异常及结构畸形发生率均高,出生后都有一定的健康存活率。     

Prenatal course and pregnancy outcome of fetuses with a transient nuchal translucency.

OBJECTIVES: This study was designed to correlate fetuses in a normal prenatal population who exhibited transient nuchal translucency (NT) with both prenatal course and pregnancy outcome. METHODS: The fetuses with abnormal NT were followed by ultrasonography at 1-2-week intervals during their prenatal course. Fetuses with NT who exhibited no detectable congenital malformations were defined as the NTO group; fetuses with abnormal NT and structural malformations but no chromosomal abnormalities were placed in the SM group; and fetuses with abnormal NT, structural malformations, and chromosomal abnormalities were categorized as the CA group. The groups were compared by: maternal age, weeks of gestation by ultrasound and the NT value at the initial exam, the maximum NT value, and the duration of abnormal NT. RESULTS: During the study period, 92 fetuses with abnormal NT were found, monochorionic twins excluded. Of the 92 fetuses, 80 were in the NTO group, 10 were in the SM group, and two were in the CA group. The maternal age and the gestational weeks at the initial diagnosis were not significantly different in the NTO and the SM groups. However, the NT value at the initial diagnosis, maximum NT value, and the duration of abnormal NT were significantly greater in the SM group than those values in the NTO group. CONCLUSIONS: Fetuses with transient nuchal translucency commonly had structural malformations, particularly fetuses with significant and large persistent NT.     

妊娠早期胎儿颈部透明层厚度与胎儿预后的前瞻性队列研究

目的探讨妊娠早期胎儿颈部透明层(NT)厚度与胎儿预后的关系。方法收集2015年12月至2018年12月于南京大学医学院附属鼓楼医院行妊娠早期胎儿NT厚度测量的单胎孕妇,共4958例建立前瞻性研究队列,进行妊娠早期胎儿结构超声筛查、妊娠早期血清学筛查、妊娠中期超声筛查及对新生儿出生后28 d的体格检查。根据妊娠早期超声筛查的结果,分为胎儿NT增厚(≥3.0 mm)者167例与NT厚度正常者4791例;将胎儿NT增厚的孕妇,分为胎儿单纯NT增厚者86例与NT增厚合并结构异常者81例。分析不同NT厚度胎儿的预后,并重点对单纯NT增厚与NT增厚合并结构异常胎儿的妊娠结局进行分析。妊娠早期超声筛查发现胎儿结构异常或血清学筛查结果为高风险的孕妇,经绒毛穿刺取样术行染色体微阵列分析(CMA)检测以明确产前诊断。结果(1)胎儿NT厚度正常孕妇的妊娠结局:共4791例孕妇,包括胎儿NT厚度正常且无结构异常者4726例,其中妊娠中期及产后新诊断结构异常83例,4688例活产;胎儿NT厚度正常但结构异常的孕妇65例,其中61例孕妇终止妊娠,4例活产。(2)胎儿单纯NT增厚孕妇的妊娠结局:86例孕妇中,66例(76.7%,66/86)行CMA检测,3例胎儿诊断为21三体综合征;除7例孕妇选择终止妊娠外,余79例行妊娠中期超声检查、新生儿出生后28 d体格检查、新生儿电话随访至6~21个月均未发现发育异常。(3)胎儿NT增厚合并结构异常孕妇的妊娠结局:81例孕妇中,73例(90.1%,73/81)行CMA检测,其中32例的胎儿为染色体非整倍体异常。70例选择终止妊娠,2例妊娠中期自然流产,9例活产。(4)NT增厚是否合并结构异常胎儿的产前诊断结果及预后比较:单纯NT增厚的胎儿染色体非整倍体的发生率为3.5%(3/86),合并结构异常者为39.5%(32/81),两者比较,差异有统计学意义(χ2=32.7,P<0.01);胎儿单纯NT增厚孕妇的健康新生儿存活率为91.9%(79/86),合并结构异常者为9.9%(8/81),两者比较,差异有统计学意义(χ2=112.3,P<0.01)。结论妊娠早期,超声筛查胎儿NT及结构,能提高出生缺陷的产前筛查率。单纯NT增厚胎儿的染色体非整倍体的发生率较低,新生儿健康存活率较高。     

Elevated first-trimester nuchal translucency increases the risk of congenital heart defects

OBJECTIVE: We sought to evaluate the association between first trimester nuchal translucency measurement and the risk for major congenital heart defect in chromosomally normal fetuses. STUDY DESIGN: First trimester (10 weeks 4 days of gestation to 13 weeks 6 days of gestation) nuchal translucency was obtained in a large prospective multicenter National Institute of Child Health and Human Development study for Down syndrome prediction. The study, which was conducted between May 1998 and December 2000, was restricted to singleton pregnancies. Gestational age was determined by crown rump length measurements. Perinatal outcomes were determined and included the frequency of major congenital heart defect, which was defined as those cases that potentially could require surgery, intensive medical therapy, or prolonged follow-up time. Logistic regression analysis was used to determine whether nuchal translucency was a significant predictor of congenital heart defect. RESULTS: There were 8167 chromosomally normal pregnancies, of which 21 cases of major congenital heart defect were identified at follow-up examination (incidence, 2.6/1000 pregnancies). The risk of congenital heart defect rose with increasing nuchal translucency measurements. The mean nuchal translucency value for the normal and congenital heart defect groups were 1.5 mm and 1.9 mm, respectively (P = .05). With a nuchal translucency measurement of < 2.0 mm, the incidence of congenital heart defect was 13 of 6757 pregnancies (1.9 of every 1000 pregnancies). At 2.0 to 2.4 mm, the incidence was 5 of 1032 pregnancies (4.8 of every 1000 pregnancies). At 2.5 to 3.4 mm, the incidence was 2 of 335 pregnancies (6.0 of every 1000 pregnancies). At > or = 3.5 mm, the incidence was 1 of 43 pregnancies (23 of every 1000 pregnancies). Logistic regression analysis confirmed that nuchal translucency was associated significantly with congenital heart defect (odds ratio, 2.1; 95% CI, 1.4-3.1; P = .0004). CONCLUSION: Increased first trimester nuchal translucency measurement was associated with a higher risk of major congenital heart defect in chromosomally normal pregnancies. The practical implications of our findings are that patients with unexplained elevations of nuchal translucency may need referral for a fetal echocardiogram.     

Agreement between predicted risk and prevalence of Down syndrome in first trimester nuchal translucency screening

The agreement between predicted risks of Down syndrome and observed prevalence was investigated in a population of 11,847 singleton pregnancies screened by first trimester nuchal translucency at a single institution. Twenty-seven cases of Down syndrome were observed; 20 were detected prenatally by nuchal translucency and maternal age screening, three by other means and four postnatally. The screened women were grouped according to their predicted risk of having an affected pregnancy, and this was compared with the observed prevalence. A significant correlation between predicted and observed prevalences was noted, thus demonstrating that risk estimates for Down syndrome based on first trimester nuchal translucency screening are accurate.     

Persistently elevated nuchal translucency and the fetal heart

Objective: To describe the outcome of fifteen cases with an elevated nuchal translucency (NT) which persisted into the second trimester as nuchal edema (NE) >6?mm whom underwent fetal echocardiography.

Materials and methods: Cases were identified following retrospective review of cardiac and genetic findings in fetuses with NE.

Results: Minor congenital heart disease was identified in 3/15 by the second trimester. Agenesis of the ductus venosus was evident in four. Pulmonary valve stenosis was diagnosed in one fetus at the 20-week scan and hypertrophic cardiomyopathy in one. However, hypertrophic cardiomyopathy or pulmonary valve stenosis was present after birth in all surviving cases by 3 months of age. On the basis of intention to treat, 11/12 survived to delivery and 9/12 survived to 28 days. There were 6 deaths before 14 months of age as a result of severe hypertrophic cardiomyopathy. Noonan syndrome was confirmed with genetic testing in 11/15 cases.

Conclusions: All fetuses with NT and NE had evidence of congenital heart disease at birth, and therefore, late gestation and postnatal review is recommended even when second trimester echocardiogram is considered normal. There is a high prevalence of Noonan syndrome and targeted genetic analysis should be considered. The outcome in these cases is poor.     

Serum parameters and nuchal translucency in first trimester screening for fetal chromosomal abnormalities

Objective To assess the relation between serum parameters and nuchal translucency in pregnancies affected by fetal aneuploidy in the first trimester.
Design Retrospective study of different serum parameters collected prior to chorionic villus sampling and measurement of nuchal translucency in relation to fetal aneuploidy.
Setting Switzerland (German and Italian sector) and Bregenz, Austria.
Population One thousand one hundred and fifty-one women aged 25 to 44 years at 10 to 13 weeks of gestation undergoing chorionic villus sampling, mostly for advanced maternal age. Fetal aneuploidy was found in 23 pregnancies including four cases of trisomy 21, five of trisomy 18 and one case of trisomy 13.
Main outcome measure Fetal karyotype, serum levels of free β-hCG, pregnancy-associated plasma protein A (PAPP-A) and alpha-fetoprotein and the measurement of nuchal translucency.
Results Serum PAPP-A was decreased in all common chromosomal abnormalities. Free β-hCG levels were increased in trisomy 21 but decreased in trisomy 18, whereas alpha-fetoprotein was low in trisomy 21, 18 and other chromosomal abnormalities. Nine of twenty-three abnormal embryos had evidence of an increased nuchal translucency. Nuchal translucency, however, did not seem to be associated with any alteration in the levels of the biochemical parameters in either chromosomally normal or abnormal embryos. A low serum PAPP-A or an increased nuchal translucency was seen in two-thirds of all pregnancies with chromosomal abnormalities.
Conclusion A nuchal translucency 3 mm and depressed serum PAPP-A levels have a good predictive value in the detection of fetal aneuploidy at 10 to 13 weeks of pregnancy. Serum free 0-hCG and alpha-fetoprotein levels may give additional information. An increased nuchal translucency was not-associated with altered serum parameters. This would allow these different markers to be used in combination.     

Screening performance of first-trimester nuchal translucency for major cardiac defects: a meta-analysis

OBJECTIVE: The purpose of this study was to evaluate the screening performance of increased first-trimester nuchal translucency for the detection of major congenital heart defects. STUDY DESIGN: A meta-analysis based on MEDLINE and EMBASE searches (up to June 2002) that assessed the diagnostic performance of increased nuchal translucency for congenital heart defect detection. Weighted sensitivity and specificity estimates (random effects) and summary receiver-operating characteristic curves were obtained. RESULTS: Eight independent studies with 58,492 pregnant women were analyzed. There was significant heterogeneity among the studies. Nuchal translucency above the 99th percentile had a sensitivity of 31% and specificity of 98.7% (random effects calculations), with a positive likelihood ratio of 24. Summary receiver-operating characteristic estimates were consistent with these values. The ability of nuchal translucency measurements above this threshold to detect cardiac malformations varied nonsignificantly (P=.64) for different congenital heart defects types (sensitivity range, 25%-55%). CONCLUSION: Nuchal translucency screening is a modestly efficient strategy for congenital heart defect detection; the use of the 99th percentile threshold may capture approximately 30% of congenital heart defects.     

Early resolution of increased nuchal translucency in a fetus with trisomy 18

The normal timing for first-trimester nuchal translucency screening of aneuploidies is 10 to 14 weeks' gestation. We describe a fetus with trisomy 18 that presented at 11 weeks with increased nuchal thickness. Reevaluation at 12 and 13 weeks showed early return to normal of the increased nuchal measurement.     

Nuchal translucency and other first-trimester sonographic markers of chromosomal abnormalities

There is extensive evidence that effective screening for major chromosomal abnormalities can be provided in the first trimester of pregnancy. Prospective studies in a total of 200,868 pregnancies, including 871 fetuses with trisomy 21, have demonstrated that increased nuchal translucency can identify 76.8% of fetuses with trisomy 21, which represents a false-positive rate of 4.2%. When fetal nuchal translucency was combined with maternal serum free-beta-human chorionic gonadotropin and pregnancy-associated plasma protein-A in prospective studies in a total of 44,613 pregnancies, including 215 fetuses with trisomy 21, the detection rate was 87.0% for a false-positive rate of 5.0%. Studies from specialist centers with 15,822 pregnancies, which included 397 fetuses with trisomy 21, have demonstrated that the absence of the nasal bone can identify 69.0% of trisomy 21 fetuses, which represents a false-positive rate of 1.4%. It has been estimated that first-trimester screening by a combination of sonography and maternal serum testing can identify 97% of trisomy 21 fetuses, which represents a false-positive rate of 5%, or that the detection rate can be 91%, which represents a false-positive rate of 0.5%. In addition to increased nuchal translucency, important sonographic markers for chromosomal abnormalities, include fetal growth restriction, tachycardia, abnormal flow in the ductus venosus, megacystis, exomphalos and single umbilical artery. Most pregnant women prefer screening in the first, rather than in the second, trimester. As with all aspects of good clinical practice, those care givers who perform first-trimester screening should be trained appropriately, and their results should be subjected to external quality assurance.     

Prospective evaluation of a first trimester screening program for Down syndrome and other chromosomal abnormalities using maternal age, nuchal translucency and biochemistry in an Australian population

BACKGROUND: A combination of maternal age and ultrasound assessment of the nuchal translucency (NT) has been used in the first trimester to screen for chromosomal abnormality. In the United Kingdom, the addition of NT screening was shown to be beneficial. AIMS: To report the sensitivity of combined first trimester biochemistry and ultrasound screening for Down syndrome in an Australian private practice specialising in obstetric ultrasound. METHODS: A prospective study in a private obstetric ultrasound practice. Over 22 months, 2121 patients were screened and data was analysed for sensitivity (detection) and false positive rates for all chromosome abnormalities. RESULTS: There were 17 chromosomal abnormalities, five of which were Down syndrome. Using maternal age alone or age and biochemistry, four of the Down syndrome cases were detected for a 29 and 19% false positive rate, respectively. Using age and NT or age, NT and biochemistry, all the Down syndrome cases were detected, for a false positive rate of 5.7 and 7.2%, respectively. The difference in detection rates for Down syndrome or other chromosomal abnormalities, using the four screening methods, did not reach statistical significance. However, the false positive rates in screening methods without ultrasound to assess the NT was significantly higher (P < 0.01). CONCLUSIONS: A combination of maternal age, NT and maternal serum biochemistry gives a high detection rate for both trisomy 21 and other chromosomal abnormalities. Down syndrome screening using either maternal age alone or age in combination with first trimester biochemistry conferred screen positive rates significantly higher than when combined with NT.