Cuckle H, van Oudgaarden E D, Mason G, Holding S
Department of Clinical Medicine, University of Leeds, UK.
Br J Obstet Gynaecol. 1994 Nov;101(11):948-53. doi: 10.1111/j.1471-0528.1994.tb13037.x.
To derive a method for revising the risk of Down's syndrome in maternal serum marker screening when there is vaginal bleeding. The effect on screening performance of routinely allowing for the presence or absence of bleeding in all women is also assessed.
Overview of published studies on the rate of reported vaginal bleeding in pregnancies with Down's syndrome, on the rate according to maternal age and on the association of bleeding with alpha-fetoprotein (AFP) level. The publications are supplemented with data on unconjugated oestriol (uE3), human chorionic gonadotrophin (hCG) and AFP levels in a consecutive series of screened women.
Routine Down's syndrome screening tests carried out on women having antenatal care at the St James's University Hospital, Leeds.
Eight hundred and nine screened women.
In five studies the rate of vaginal bleeding in Down's syndrome pregnancies was 1.7 times that in unaffected pregnancies on average. In three studies, the vaginal bleeding rate increased proportionally by 2.2% on average for each year of maternal age. Three studies and our own data were consistent with a 10% increase in the mean AFP level associated with vaginal bleeding, but it did not appear to materially alter uE3 and hCG levels or the standard deviations and correlation coefficients for any of the three analytes. An individual woman's risk was calculated by multiplying her age-specific odds of Down's syndrome by two likelihood ratios, one relating to the vaginal bleeding itself and one from the marker levels. Routine allowance for the presence or absence of vaginal bleeding was estimated to increase the detection rate by less than 1%.
Our method is of clinical value in revising the risk when there is concern that vaginal bleeding might be responsible for a negative maternal serum Down's syndrome screening result. A policy of routinely incorporating information on vaginal bleeding in risk estimation for all women would have too small an effect on overall screening performance to recommend it.
推导一种在出现阴道出血时修正孕母血清标志物筛查中唐氏综合征风险的方法。同时评估在所有女性中常规考虑有无出血情况对筛查性能的影响。
对已发表的关于唐氏综合征妊娠中报告的阴道出血发生率、根据孕母年龄的发生率以及出血与甲胎蛋白（AFP）水平关联的研究进行综述。对一系列连续接受筛查的女性的未结合雌三醇（uE3）、人绒毛膜促性腺激素（hCG）和AFP水平的数据进行补充分析。
在利兹圣詹姆斯大学医院对接受产前检查的女性进行常规唐氏综合征筛查测试。
809名接受筛查的女性。
在五项研究中，唐氏综合征妊娠中阴道出血的发生率平均是未受影响妊娠的1.7倍。在三项研究中，孕母年龄每增加一岁，阴道出血率平均相应增加2.2%。三项研究以及我们自己的数据均显示，与阴道出血相关的平均AFP水平升高了10%，但这似乎并未实质性改变uE3和hCG水平，以及这三种分析物中任何一种的标准差和相关系数。通过将个体女性的唐氏综合征年龄特异性比值比乘以两个似然比来计算其风险，一个似然比与阴道出血本身相关，另一个与标志物水平相关。据估计，常规考虑有无阴道出血会使检出率提高不到1%。
当担心阴道出血可能导致孕母血清唐氏综合征筛查结果为阴性时，我们的方法对于修正风险具有临床价值。对所有女性在风险评估中常规纳入阴道出血信息的策略，对整体筛查性能的影响过小，不值得推荐。
