胎儿颈项透明层增厚与染色体异常的关系

目的 通过超声测量胎儿颈项透明层厚度(NT),探讨NT增厚与胎儿染色体异常的关系。 方法 选择2007年2月至2009年12月在北京大学人民医院产前检查的孕10~22周经腹超声检查胎儿NT增厚的孕妇78例,行羊水或脐带血穿刺进行胎儿染色体核型分析,并进行超声及分娩结局的随访。 结果 78例NT增厚病例中,染色体异常3例,均为21-三体综合征,发生率为3.85%(3/78)。6例发生不良妊娠结局,其中5例伴胎儿异常,胎儿异常分别为右侧脑积水和脑脊膜膨出、多囊肾、心脏畸形、风疹病毒感染和全身水肿。 结论 NT增厚对染色体异常特别是21-三体综合征的早期筛查具有重要意义,是孕早中期产前超声筛查的主要指征之一。     

早孕期产前超声检查诊断胎儿颈项透明层增厚的临床价值探讨

目的:探讨早孕期产前超声检查诊断胎儿颈项透明层（NT）增厚对临床诊断胎儿异常的价值。方法:于孕11—13⁺⁶孕周测量胎儿NT,超声随访观察至出生。结果:在5288例早孕期胎儿中,共检测出75例NT增厚,6例失访,11例染色体核型异常;58例染色体核型正常,但其中14例超声随访发现严重并发症,44例超声随诊至出生未见明显异常。结论:早孕期产前超声检查诊断胎儿NT增厚对于临床检出胎儿异常具有较高的诊断价值。     

彩超检测胎儿颈项透明层厚度与胎儿发育异常的应用研究

目的:探讨彩超检测胎儿颈项透明层(NT)增厚与胎儿发育异常的有关因素、临界值的确定以及临床的诊断价值。方法:应用GEVoluson730Expert、GEVolusonE8型彩色多普勒超声诊断仪,对孕11～13+6周、顶臀长(CRL)在45～84mm范围的1921例孕妇进行经腹超声检查,测量胎儿NT值,并随访至出生后3天。对所有孕妇的NT值按照不同的临界值进行分组,计算其灵敏度、特异度、阳性预测值和阴性预测值;并将胎儿正常的孕妇按照不同的孕周和不同的年龄段分组对其NT值进行比较。结果:①1921例孕妇中,经超声随诊和出生后随访发现胎儿发育异常共30例,其中27例NT值≥3.0mm,3例NT值<3.0mm。27例NT值≥3.0mm中,染色体核型异常4例,胎儿结构异常23例;3例NT值<3.0mm中,染色体核型异常1例,胎儿结构异常2例。另有25例虽然NT值≥3.0mm,但超声随诊至出生未见明显异常。②1891例胎儿正常的孕妇其孕11～11+6周、孕12～12+6周和孕13～13+6周的NT值比较,差异有高度统计学意义(F=5.550,P=0.005);其不同年龄阶段的NT值比较,差异无统计学意义(P>0.05)。③选择不同的临界值,灵敏度与特异度有所不同,当NT值≥3.0mm,其灵敏度为90.00%,特异度为98.68%,阳性预测值为93.10%,阴性预测值为98.24%较为平衡。结论:正常的早期妊娠中,随着孕周的增加,胎儿NT值逐渐增加,而孕妇年龄对NT值无影响;胎儿NT值的异常增厚与胎儿发育异常有着密切的关系,彩超检测NT厚度可作为孕早期筛查胎儿畸形的一个重要指标,NT值≥3.0mm作为诊断界值较为理想。     

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。     

中孕期超声筛查胎儿染色体异常软指标的临床价值

目的探讨中孕期超声筛查发现胎儿染色体异常软指标与胎儿染色体异常之间的关系,对超声软指标的临床价值作一评估。方法2004年2月至2006年11月在复旦大学附属妇产科医院产前筛查孕妇8810例,共筛查8883例胎儿(其中73例为双胎),中孕期详细超声筛查有无结构异常及染色体异常软指标,根据孕妇年龄、血清学筛查结果及超声检查综合评定,决定是否行羊膜腔穿刺染色体检查。染色体异常软指标主要包括:颈项软组织增厚、肱骨股骨偏短、轻度肾盂扩张、心室强光点、肠管强回声等。结果8883例胎儿中,发现染色体异常软指标598例,占6.73%。超声软指标诊断21-三体综合征敏感度为69.23%,特异度为93.36%,假阳性率6.74%。结论中孕期超声染色体异常软指标,对于筛查胎儿染色体异常具有重要的临床价值。     

孕妇超声下胎儿颈项透明层筛查的临床分析

目的分析孕妇妊娠11~14周胎儿颈项透明层(nuchal translucency,NT)超声筛查的临床意义。方法收集2012年1月至2012年12月在北京妇产医院妊娠11~14周进行超声NT筛查的孕妇共10 982例,以NT≥2.5mm为临界值。结果①10 982例孕妇中≥2.5mm者173例,随访到结局者165例,染色体异常者12例,21-三体5例,18-三体5例,13-三体1例,45XO 1例;胎儿外观畸形而染色体正常者9例;②对临床资料判断胎儿染色体正常者153例(通过孕期产检及分娩后新生儿查体随访,并非有染色体核型分析者)及染色体异常者12例的NT厚度进行完全随机两样本均数的比较,得出结论 (t<0.05),差异有统计学意义;③染色体正常者中对有无胎儿外观畸形进行NT厚度完全随机两样本均数的比较,结果 (P<0.05),差异有统计学意义。结论对妊娠11~14周孕妇进行NT超声筛查有很重要意义,可以尽早筛出胎儿染色体异常及外观畸形胎儿,降低大孕周引产风险。     

早孕期胎儿鼻骨缺失与染色体异常关系的研究

目的:探讨早孕期胎儿鼻骨缺失与胎儿染色体异常之间的关系。方法:回顾性分析2016年1月至2017年12月广州医科大学附属第三医院产前诊断及胎儿医学中心和福建医科大学附属第一医院超声影像科早孕期超声检查提示胎儿鼻骨缺失的相关资料,分析胎儿单纯鼻骨缺失及其在合并其他超声异常时对诊断染色体异常的价值。结果:高龄孕妇的胎儿单纯鼻骨缺失及合并其他超声异常时胎儿染色体异常的发生率分别为6.78%和75.00%,同非高龄孕妇的胎儿染色体异常率(分别为0.80%和42.50%)比较,差异均有统计学意义(P<0.05)。胎儿单纯鼻骨缺失的染色体异常率为2.72%,当合并其他异常指标时,胎儿染色体异常率升至58.75%,差异有统计学意义(P<0.01)。胎儿鼻骨缺失在合并颈项透明层(NT)增厚时,胎儿染色体异常的总发生率为60.81%。当NT>3.5 mm时胎儿染色体异常率达77.78%,与NT≤3.5 mm时的染色体异常发生率(34.48%)比较,差异有统计学意义(P<0.05)。结论:早孕期超声检查提示胎儿鼻骨缺失时,需详细的胎儿超声结构筛查评估,当发现合并其他超声异常时,临床医师应向孕妇提供遗传咨询,建议行产前诊断以排除胎儿染色体异常。     

早孕期超声检查诊断胎儿畸形的临床价值

目的：探讨早孕期超声检查诊断胎儿畸形的临床价值。方法：选取我院2011年12月至2013年12月接收的行早孕期超声检查的1085例孕妇为研究对象,检查指标包括颈项透明带厚度、鼻骨长度、三尖瓣血流与静脉导管血流频谱,并观察胎儿心脏、胃泡、四肢与头颅结构,参照孕妇意愿决定是否终止异常妊娠;剩余孕妇均行中孕期超声检查,并对其最终的妊娠结局进行追踪。结果：纳入研究的行早孕期胎儿异常检查的检出率为6．6％（72例）;1045例孕妇行中孕期超声检查,胎儿异常检出率为5．3％（55例）。结论：早孕期行超声检查时,早发性、严重性异常胎儿的检出率较高,但不能取代中孕期超声检查。     

双胎输血综合征早孕期超声预测指标初探

目的:实施前瞻性研究探讨孕11~14周超声筛查单绒毛膜双胎颈项透明层厚度(nuchal translucency,NT)不一致及静脉导管(ductus venosus,DV)血流频谱异常预测双胎输血综合征(twintwin transfusion syndrome,TTTS)的有效性。方法:选择2011年1月至2013年12月在四川大学华西第二医院就诊,孕11~14周经超声筛查为单绒毛膜双胎孕妇。测量胎儿NT,以双胎儿NT差值0.6 mm为NT不一致;采集DV血流频谱,以一个胎儿出现A波倒置或消失为DV血流频谱异常。随访相关数据及胎儿结局。结果:孕11~14周超声筛查单绒毛膜双胎孕妇,最终纳入67例。胎儿中位顶臀长(CRL)66.00±0.96 mm,中位妊娠孕周为12周。产前超声诊断TTTS 13例(19.4%),均在孕16~28周诊断,产后或引产后证实。NT不一致19例,其中7例发展为TTTS,NT不一致筛查TTTS敏感性53.8%(95%CI 29.0~76.8),特异性77.8%(95%CI 65.1~86.8)。DV血流频谱异常16例,其中11例发展为TTTS(9例一胎DV血流频谱异常,2例双胎DV血流频谱均异常),且都合并NT不一致。双胎DV血流频谱异常联合NT不一致筛查TTTS敏感性84.6%(95%CI 57.8~95.7),特异性90.7%(95%CI 80.1~96.0)。结论:孕11~14周单绒毛膜双胎NT不一致及DV血流频谱异常可能是双胎儿血流动力学不平衡的早期表现,对于单绒毛膜双胎行NT检查时需要评估DV血流频谱状况,NT不一致联合DV血流频谱异常可能是预测TTTS的早期指标。     

妊娠早期超声多指标筛查胎儿染色体异常的临床价值

目的 探讨妊娠早期超声多指标筛查胎儿染色体异常的临床价值.方法 对2008年9月至2010年9月在暨南大学附属第一医院产科就诊的2789例妊娠早期(11～13+6周)单胎初产孕妇超声测量胎儿颈项透明层(nuchal translucency,NT)厚度,记录胎心率(fetal heart rate,FHR)、面部角度(facial angle,FA)、静脉导管(ductus venosus,DV)、三尖瓣反流(tricuspid reverse,TR)、胎儿鼻骨(nasal bone,NB)等超声指标,观察胎儿结构.全部超声指标检查结果输入Astraia风险筛查软件计算染色体异常风险值(＞1/300为高风险截断值),根据知情同意原则对高风险者取绒毛或羊水进行染色体核型产前诊断.所有研究对象随访至分娩后6个月.率的比较用x2检验或Fisher精确概率法.结果 (1) 2789例孕妇筛查出21三体高风险107例,其中96例接受侵入性产前诊断,诊断染色体异常16例,染色体异常发生率为0.6％(16/2789),其中6例21-三体.2789例孕妇中,超声筛查21-三体高风险孕妇4例,最终确诊21-三体6例,假阳性率为3.6％ (101/2783).(2) NT≥2.5 mm者196例,21-三体高风险66例,均经绒毛穿刺诊断,发现染色体异常16例;有创性检查率2.3％(66/2789).(3)≥35岁孕妇占筛查总数的6.7％(186/2789),其中检出21三体高风险32例,占21-三体高风险总数的29.9％ (32/107);诊断21-三体2例,21-三体检出率为1.1％(2/186);年龄＜35岁者21-三体检出率为0.2％(4/2597);年龄≥35岁和年龄＜35岁人群中胎儿21-三体检出率差异无统计学意义(P=0.055).(4)筛查过程诊断胎儿结构异常13例,其中5例染色体核型异常.结论 妊娠早期超声多指标筛查将明显提高染色体异常胎儿检出率并降低假阳性和假阴性率,大大降低有创性检查率.尤其对高龄孕妇的染色体异常风险评估更有明显的指导意义.妊娠早期超声筛查不仅可以有效检出核型异常,同时可以诊断严重的胎儿结构异常.     

First-trimester ductus venosus velocimetry in relation to nuchal translucency thickness and fetal karyotype.

AIM: To evaluate first-trimester ductus venosus flow in relation to nuchal translucency (NT) and fetal karyotype. METHODS: Ductus venosus flow was measured in fetuses with NT greater than or equal to the 95th centile (group A) and in fetuses with NT less than the 95th centile (group B). The waveforms were classified as normal if the lowest forward velocity during atrial contraction (ACV) was positive and abnormal if it was absent or negative. The results were compared with the fetal karyotype. RESULTS: Ductus venosus measurement was carried out in 330 fetuses. In group A, there were 156 fetuses: in 4 cases, it was not possible to obtain the measurement, and in the other 152 cases, 93 (61%) had a normal ACV and 59 (39%) an abnormal ACV. NT thickness was significantly greater in fetuses with abnormal ACV. In 34 out of 156 cases (22%), chromosomal abnormalities were found. Twenty-three chromosomopathies out of 33 (70%) had an abnormal ACV, and 10 (30%) had a normal ACV. A significant association between abnormal karyotype and abnormal ACV was found. Ductus venosus measurement was carried out in 174 fetuses of group B. In 1 case, it was not possible to obtain the measurement. One hundred and seventy-one (99%) cases had a normal ACV, and in 2 (1%) cases the ACV was abnormal. No chromosomal abnormalities were found in group B. Considering group A and group B, a significant association between the finding of an enlarged NT and abnormal ACV was detected (p < 0.05). CONCLUSIONS: An abnormal ACV is more frequent in fetuses presenting enlarged NT than in those having normal NTs and in fetuses having the larger nuchal thickness. The probability of having a chromosomal abnormality in fetuses with enlarged NT is greater when an abnormal ACV is found.     

Search for hemodynamic compromise at 11-14 weeks in monochorionic twin pregnancy: is abnormal flow in the ductus venosus predictive of twin-twin transfusion syndrome?

BACKGROUND AND OBJECTIVES: Twin-twin transfusion syndrome is a devastating complication of monochorionic twin pregnancies. The presence of increased nuchal translucency thickness (NT) in one of the monochorionic twins has been associated with an increased risk of developing this syndrome. One of the most plausible mechanisms for increased nuchal translucency is heart failure, indirectly manifested by abnormal blood flow in the ductus venosus. We aimed to clarify the pathophysiology of increased NT found more frequently in monochorionic twins prone to develop twin-twin transfusion syndrome. DESIGN: We present 50 cases of monochorionic twin pregnancies in which nuchal translucency thickness was measured and ductus venosus blood flow evaluation was performed at 11-14 weeks of gestation. RESULTS: Whenever the fetuses of a twin pregnancy were found to have discrepant nuchal translucency thickness measurements and abnormal flow in the ductus venosus was found in the fetus with increased nuchal translucency thickness, twin-twin transfusion syndrome eventually developed. Progression to twin-to-twin transfusion syndrome was not observed in the twins displaying no intertwin difference in nuchal translucency thickness measurements and it was not observed in those with discrepant nuchal translucency thickness but normal flow in the ductus venosus of both fetuses. In the two cases which developed twin-to-twin transfusion syndrome, fetoscopic laser coagulation of the vascular anastomoses was successfully carried out at 18 weeks and normalization of the venous return was recorded. CONCLUSIONS: Both increased nuchal translucency and abnormal flow in the ductus venosus in monochorionic twins may be early manifestations of haemodynamic imbalance between donor and recipient. The combined evaluation of both parameters in monochorionic twin pregnancies may constitute an effective method for identifying those at risk of developing twin-to-twin transfusion syndrome.     

Application of ductus venosus Doppler velocimetry for the detection of fetal aneuploidy in the first trimester of pregnancy

OBJECTIVE: To test the hypothesis the application of ductus venosus Doppler velocimetry may serve as a screening tool between 10 and 14 weeks' gestation for the detection of fetuses with chromosomal abnormalities. METHODS: 372 consecutive fetuses were studied. Based on prior study, a chromosomal abnormality was suspected when either the nuchal translucency was above the 95th centile, or there was reversed or absent flow in the ductus venosus during atrial contraction. Sensitivity, specificity, and the negative and positive predictive values were calculated. RESULTS: There were 29 chromosomally abnormal fetuses. Of these 29 fetuses, ductus venosus blood flow during atrial contraction was either absent (n = 2) or reversed (n = 25) in 93.1%. In the chromosomally normal fetuses (n = 343), only 6 (1.7%) had abnormal Doppler profiles in the ductus venosus (specificity = 98.3%, positive and negative predictive values = 81.8% and 99.4%, respectively). CONCLUSION: The Doppler waveform of the ductus venosus was at least equal to NT thickness measurement for the detection of chromosomal abnormalities.     

Screening for adverse pregnancy outcome by ductus venosus Doppler at 11-13+6 weeks of gestation

OBJECTIVE: To estimate the independent contribution of abnormal flow in the ductus venosus at 11 to 13+6 weeks of gestation in the prediction of major fetal abnormalities and fetal death. METHODS: This was a prospective assessment of singleton pregnancies by maternal history, serum free beta-hCG, pregnancy-associated plasma protein A (PAPP-A), fetal nuchal translucency thickness, and ductus venosus Doppler. The patients were subdivided into five groups: normal outcome (n=10,120), miscarriage or fetal death (n=185), abnormal karyotype (n=95), and major cardiac (n=20) or noncardiac defect (n=70). Regression analysis was performed to determine the significance of the contribution to adverse outcome of reversed a-wave in the ductus venosus, maternal characteristics, fetal delta nuchal translucency, maternal serum log PAPP-A multiples of the median, and log free beta-hCG multiples of the median. RESULTS: The prevalence of reversed a-wave was significantly higher in the groups with miscarriage or fetal death (10.8%), abnormal karyotype (62.1%), and fetal cardiac defect (25.0%) than in the normal outcome group (3.7%), but not noncardiac defect (4.3%). An adverse outcome was observed in 2.7% of the fetuses with nuchal translucency at or below the 95th centile (in 2.6% of those with normal a-wave and in 7.0% of those with reversed a-wave) and in 19.3% of the fetuses with nuchal translucency above the 95th centile (in 8.9% of those with normal a-wave and in 70.9% of those with reversed a-wave). CONCLUSION: Reversed a-wave is associated with increased risk for chromosomal abnormalities, cardiac defects, and fetal death. However, in about 80% of cases with reversed a-wave, the pregnancy outcome is normal.     

Screening performance of first trimester nuchal translucency, ductus venosus blood flow and tricuspid regurgitation for cardiac defects

The present article summarises current knowledge on the risk of fetal cardiac malformations in fetuses with increased nuchal translucency (NT), abnormal ductus venosus blood flow pattern and tricuspid regurgitation. The risk of congenital heart disease (CHD) increases with increasing NT. However, nuchal translucency screening is only modestly efficient in the detection of congenital heart disease in low-risk pregnancies. If the nuchal translucency is normal, abnormal ductus venosus blood flow and tricuspid regurgitation show low sensitivities as single screening parameters. The combination of all 3 markers might increase the detection rates. Fetal echocardiography at 20 weeks of gestation is recommended in foetuses with an NT ≥95th percentile, as the incidence of CHD increases 2.5-fold. When the NT measurement is ≥99th percentile, the risk of CHD increases 10-fold. In this high-risk group and in fetuses with tricuspid regurgitation and/or an abnormal DV flow pattern along with an increased NT, first or early second trimester echocardiography performed by experts is warranted. The early examination of the fetal heart should be completed by a detailed echocardiogram at around 20 weeks of gestation.     

First-trimester ductus venosus, nasal bones, and Down syndrome in a high-risk population

OBJECTIVE: Assessing the role of fetal ductus venosus and nasal bones evaluation in first-trimester screening for Down syndrome. METHODS: This was a prospective cohort study in a tertiary referral fetal medicine unit involving 628 consecutive fetuses undergoing chorionic villus sampling. The indication for chorionic villus sampling was an increased risk (more than 1:300) for trisomy 21 based on maternal age and nuchal translucency screening in 313 cases (54.7%), increased maternal age in 195 (34.1%), and other in 64 (11.2%). Immediately before chorionic villus sampling, an ultrasound examination was performed. The pattern of blood flow in the ductus venosus and the presence or absence of the nasal bones was noted. RESULTS: A satisfactory examination of both ductus venosus and nasal bones was possible in 572 fetuses. Of these, 497 (86.9%) had a normal karyotype, and 47 (8.2%) were affected with Down syndrome. The likelihood ratio for trisomy 21 was 7.05 (95% confidence interval 4.27-11.64) in the case of abnormal ductus venosus flow and 6.42 (95% confidence interval 3.86-10.67) in the case of absent nasal bones. CONCLUSION: In addition to increased fetal nuchal translucency, Down syndrome is significantly associated with first-trimester abnormal flow velocity patterns in the ductus venosus and hypoplasia of the nasal bones.     

Ductus venosus blood flow evaluation at 11-14 weeks in the anticipation of twin-twin transfusion syndrome in monochorionic twin pregnancies

Twin-twin transfusion syndrome (TTTS) is a serious complication, occurring in about 15% of monochorionic twin pregnancies. Strong evidence suggests that increased fetal nuchal translucency thickness (NT) in one of the monochorionic twins is highly predictive of TTTS. One of the most plausible mechanisms for increased NT is heart failure, which can be indirectly manifested by abnormal blood flow in the ductus venosus. We present 20 cases of monochorionic twin pregnancies in which both NT thickness and ductus venosus blood flow evaluation were performed at 11-14 weeks. Whenever both fetuses showed discrepant NT, and abnormal ductal flow was found in the fetus with increased NT, TTTS eventually developed. In none of the twins displaying similar NT measurements, and in those with discrepant NT but normal flow in the ductus venosus of both fetuses, was the progression to TTTS observed. In the two cases that developed TTTS, fetoscopic laser coagulation of the vascular anastomoses was successfully carried out at 18 weeks, and normalization of the venous return was recorded. Increased NT and abnormal flow in the ductus venosus in monochorionic twins may be early manifestations of hemodynamic imbalance between donor and recipient The combined evaluation of both parameters in monochorionic twin pregnancies could be an effective screening method.     

The ductus venosus in early pregnancy and congenital anomalies

The ductus venosus (DV) is a tiny vessel leading oxygenated blood from the placenta to the fetal heart and its flow assessment has been used as an indicator of fetal acidemia. At 11 to 14 weeks, the fetuses with increased nuchal translucency also showing an abnormal DV blood flow were consistently found to be aneuploid. Early cardiac dysfunction, signaled by abnormal DV blood flow, was suggested as the underlying cause of increased nuchal translucency. Detection rates for aneuploidy with the use of DV blood flow studies range from 59 to 93% with 2 to 21% false-positive rates. In fetuses with normal karyotype, an abnormal DV flow pattern signals cardiac defects or adverse perinatal outcome.     

Screening for aneuploidy in the first trimester by assessment of blood flow in the ductus venosus

Objective To assess the role of ductus venosus Doppler assessment in screening for fetal aneuploidy in pregnancies at 11–14 weeks of gestation.
Design Prospective observational study.
Setting In a tertiary referral fetal medicine unit.
Population Two hundred fifty-six consecutive pregnancies between 11 and 14 weeks of gestation referred to our unit.
Methods Nuchal translucency was measured and colour Doppler imaging was used to assess normal (forward) or abnormal (absence/reversed) ductus venosus flow during atrial contraction.
Main outcome measures Fetal karyotype, structural abnormalities and pregnancy outcomes.
Results The nuchal translucency measurement was ≥95th centile in 90 (35.2%) pregnancies, and 123 (48.0%) had a nuchal translucency-related risk of ≥1:300. There were 46 chromosomally abnormal pregnancies and six euploid pregnancies with adverse outcome. The prevalence of abnormal ductus venosus Doppler waveforms in normal pregnancies was 4.49% (95% CI 1.76–8.76%). The sensitivities of abnormal nuchal translucency measurement alone, ductus venosus velocimetry alone or nuchal translucency and ductus venosus combined for Down's Syndrome were 80.4%, 58.7% and 93.5%, respectively. The likelihood ratios for aneuploidy with abnormal nuchal translucency measurement alone, ductus venosus velocimetry alone or nuchal translucency and ductus venosus combined were 3.33, 9.83 and 3.48, respectively.
Conclusion There is clear association between abnormal flow in the ductus venosus and fetal aneuploidy. The use of ductus venosus velocimetry in combination with nuchal translucency is better than either test alone, since it increases the sensitivity in the detection of Down's Syndrome to 94% and decreases the likelihood ratio of a negative test to 0.08.     

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.