Wøjdemann K R, Christiansen M, Sundberg K, Larsen S O, Shalmi A, Tabor A
Copenhagen University Hospital, Department of Obstetrics and Gynaecology, Hvidovre Hospital, Kettegaard Allé 30, DK-2650 Hvidovre, Denmark.
Ultrasound Obstet Gynecol. 2001 Dec;18(6):641-4. doi: 10.1046/j.0960-7692.2001.00592.x.
To develop and apply a quality control system in a Down syndrome screening study using nuchal translucency as an interventional marker.
In a prospective Down syndrome screening study fetal nuchal translucency thickness was measured in 9236 of the 10 045 examined pregnancies. For quality assessment two models were introduced: firstly, image-scoring evaluation of the nuchal translucency thickness measurements and secondly, establishment of the distributions of nuchal translucency multiples of the median over time and the influence of intervention.
The observer variability in the image-scoring evaluation was high with a kappa value of 0.48 in the overall validation. A revised model showed better interobserver agreement with a kappa value of 0.58; however, comparing the individual criteria the differences were still unsatisfactory, i.e. we found highly significant differences in the criteria "position of the fetus" (P = 0.0026) and "magnification of the image" (P = 0.0001). Regarding the distributions of the nuchal translucency multiples of the median, the median stabilized after a short learning phase representing the practical part of the sonographer's certification to nuchal translucency screening. In groups of medians of 50 nuchal translucency multiples of the median the intergroup standard deviation decreased from 0.100-0.060 after the learning phase to 0.046 after intervention.
When well-trained certified examiners perform nuchal translucency screening, continuous evaluation of the distribution of the nuchal translucency multiples of the median seems to be a good method to assess the quality for a center and may also be used to identify individual examiners deviating from the mean performance. The image-scoring methods we introduced cannot be recommended for quality control in a nuchal translucency screening program.
在一项以颈部半透明厚度作为干预指标的唐氏综合征筛查研究中，开发并应用一种质量控制系统。
在一项前瞻性唐氏综合征筛查研究中，对10045例受检妊娠中的9236例测量了胎儿颈部半透明厚度。为进行质量评估，引入了两种模式：其一，对颈部半透明厚度测量进行图像评分评估；其二，确定颈部半透明厚度中位数倍数随时间的分布以及干预的影响。
在整体验证中，图像评分评估的观察者变异性较高，kappa值为0.48。一个修订模型显示观察者间一致性更好，kappa值为0.58；然而，比较各个标准，差异仍然不令人满意，即我们发现在“胎儿位置”标准（P = 0.0026）和“图像放大倍数”标准（P = 0.0001）上存在高度显著差异。关于颈部半透明厚度中位数倍数的分布，在经历一个短暂的学习阶段后中位数趋于稳定，该学习阶段代表超声检查人员颈部半透明筛查认证的实践部分。在每组50个颈部半透明厚度中位数倍数的中位数组中，组间标准差从学习阶段后的0.100 - 0.060降至干预后的0.046。
当训练有素的认证检查人员进行颈部半透明筛查时，持续评估颈部半透明厚度中位数倍数的分布似乎是评估一个中心质量的好方法，也可用于识别偏离平均表现的个体检查人员。我们引入的图像评分方法不推荐用于颈部半透明筛查项目的质量控制。
