Dimitrova V, Markov D, Chernev T, Karag'ozova Zh, Mazneĭkova V, Andonova S, Vŭzharova R
Akush Ginekol (Sofiia). 2005;44(1):32-7.
To assess the feasibility of nuchal translucency [NT] measurement as a screening tool for Down syndrome [DS] and other chromosomal anomalies [ChA] between 11-14 weeks of gestation [w.g.].
A longitudinal prospective follow up study was carried out at a tertiary referral center including 408 singleton pregnancies between 11+0 and 14+0 w.g. Three experienced sonographers performed transabdominal and/or transvaginal scans using high-resolution ultrasound equipment. The ultrasound examinations included assessment of fetal number and viability, NT measurement and fetal anatomy survey. Down syndrome [DS] risk was calculated using the specialized computer program provided by the Fetal Medicine Foundation [FMF], UK. In cases of estimated DS risk > or = 1:300 invasive prenatal diagnosis was offered--chorionic villus sampling [CVS] between 11-14 w.g. or amniocentesis [AC] after 15 w. g., as well as follow-up scans including fetal echocardiography. The samples were tested by cytogenetic analysis, DNA analysis and/or FISH. When chromosomal fetal abnormality was detected termination of pregnancy was an option. Pregnancy outcome was ascertained from hospital records, referring physicians or the patients themselves.
108 (26%) out of the 408 women were ?35 years and 300 (74%)--below that age. A total number of 9 fetal chromosomal anomalies [ChA] were found including 6 cases with DS, 2--with trisomy 18 [T18] and 1--with Turner syndrome. The overall sensitivity for DS was 66.7% for a false-positive rate [FPR] of 13.4%. The figures for all ChA were 77.7% and 12.8%, respectively. All three cases of ChA other than DS were in the screen-positive group. The overall sensitivity and FPR for ChA for patients > or = 35 years was 80% and 35%, while for patients < 35 years it was 75% and 5.1 %, respectively. Diagnostic invasive procedures were performed in 50 out of 58 screen-positive cases, including 7 of the cases with ChA. In all 7 cases with prenatal diagnosis of fetal ChA the parents chose to terminate the pregnancy.
First trimester DS screening by NT measurement has high sensitivity and specificity. Screening for other chromosomal abnormalities missed by second trimester biochemical serum tests is also possible. Invasive prenatal diagnosis is performed at an early gestational age when termination of affected pregnancies by D&C is still an option. Other important advantages are the possibility of screening for ChA in multiple gestations, as well as early diagnosis of major fetal anomalies.
评估孕11至14周时颈部透明带（NT）测量作为唐氏综合征（DS）及其他染色体异常（ChA）筛查工具的可行性。
在一家三级转诊中心进行了一项纵向前瞻性随访研究，纳入408例孕11⁺⁰至14⁺⁰周的单胎妊娠。三名经验丰富的超声检查医师使用高分辨率超声设备进行经腹和/或经阴道扫描。超声检查包括评估胎儿数量和存活情况、NT测量及胎儿解剖结构检查。使用英国胎儿医学基金会（FMF）提供的专业计算机程序计算唐氏综合征（DS）风险。若估计DS风险≥1:300，则提供侵入性产前诊断——孕11至14周时进行绒毛取样（CVS），或孕15周后进行羊膜腔穿刺术（AC），以及包括胎儿超声心动图在内的后续扫描。样本通过细胞遗传学分析、DNA分析和/或荧光原位杂交（FISH）进行检测。若检测到胎儿染色体异常，可选择终止妊娠。通过医院记录、转诊医生或患者本人确定妊娠结局。
408名女性中，108名（26%）年龄≥35岁，300名（74%）年龄低于该年龄。共发现9例胎儿染色体异常（ChA），包括6例唐氏综合征（DS）、2例18三体（T18）和1例特纳综合征。DS总体敏感性为66.7%，假阳性率（FPR）为13.4%。所有ChA的相应数字分别为77.7%和12.8%。除DS外的所有3例ChA均在筛查阳性组。年龄≥35岁患者ChA的总体敏感性和FPR分别为80%和35%，年龄＜35岁患者分别为75%和5.1%。58例筛查阳性病例中有50例进行了诊断性侵入性检查，其中7例为ChA病例。所有7例产前诊断为胎儿ChA的病例中，父母均选择终止妊娠。
孕早期通过NT测量进行DS筛查具有高敏感性和特异性。对孕中期生化血清学检查遗漏的其他染色体异常进行筛查也是可行的。在孕早期进行侵入性产前诊断，此时通过刮宫终止受影响妊娠仍是一种选择。其他重要优势包括对多胎妊娠进行ChA筛查的可能性，以及对主要胎儿异常的早期诊断。
