Winsor E J, Tomkins D J, Kalousek D, Farrell S, Wyatt P, Fan Y S, Carter R, Wang H, Dallaire L, Eydoux P, Welch J P, Dawson A, Lin J C, Singer J, Johnson J, Wilson R D
Department of Laboratory Medicine and Pathobiology, The Toronto Hospital, Eaton 3-301, 200 Elizabeth Street, Toronto, Ontario, Canada, M5G 2C4.
Prenat Diagn. 1999 Jul;19(7):620-7. doi: 10.1002/(sici)1097-0223(199907)19:7<620::aid-pd599>3.0.co;2-e.
Cytogenetic results from a large multicentre randomized controlled study of 2108 amniotic fluids obtained at 11+0-12+6 weeks (EA) and 1999 fluids at 15+0-16+6 weeks (MA) were compared. There was no statistically significant difference in the rate of chromosome abnormalities (EA =1.9 per cent; MA=1.7 per cent) or level III mosaicism (EA=0.2 per cent; MA= 0.2 per cent) between the groups. Level I and Level II mosaicism occurred more frequently in MA. Maternal cell contamination was not significantly different between the groups, but maternal cells only were analysed from one bloody EA fluid. The number of repeat amniocenteses because of cytogenetic problems was 2.2 per cent in the EA group compared with only 0.3 per cent in the MA group. On average, culture of EA fluids required one day more than MA fluids. Although both culture success (97.7 per cent) and accuracy (99.8 per cent) were high for patients randomized to the EA group, routine amniocentesis prior to 13 weeks' gestation is not recommended for clinical reasons including an increased risk of fetal loss and talipes equinovarus.
对在孕11⁺⁰至12⁺⁶周获取的2108份羊水样本（早孕期组，EA）以及在孕15⁺⁰至16⁺⁶周获取的1999份羊水样本（中孕期组，MA）进行的一项大型多中心随机对照研究的细胞遗传学结果进行了比较。两组之间在染色体异常率（早孕期组 = 1.9%；中孕期组 = 1.7%）或III级嵌合体水平（早孕期组 = 0.2%；中孕期组 = 0.2%）方面无统计学显著差异。I级和II级嵌合体在中孕期组中出现得更为频繁。两组之间母血细胞污染无显著差异，但仅对一份血性早孕期羊水样本中的母细胞进行了分析。因细胞遗传学问题进行重复羊膜腔穿刺术的比例在早孕期组为2.2%，而在中孕期组仅为0.3%。平均而言，早孕期羊水样本的培养比中孕期羊水样本多需要一天时间。尽管随机分配到早孕期组的患者培养成功率（97.7%）和准确率（99.8%）都很高，但出于包括胎儿丢失风险增加和马蹄内翻足等临床原因，不建议在妊娠13周前进行常规羊膜腔穿刺术。
