Department of Transfusion Medicine, University Medical Center, Göttingen, Germany.
Prenat Diagn. 2011 Dec;31(13):1300-4. doi: 10.1002/pd.2889. Epub 2011 Oct 26.
Before noninvasive prenatal diagnosis on the fetal Rhesus D status (NIPD RhD) can be implemented on a mass-scale, it is crucial to define requirements regarding sample transport. The aim of this study was to determine the relation between the transport time of samples for NIPD and the concentration of fetal DNA in maternal plasma.
We analyzed qualitative and quantitative data obtained in a previous study performed with real-time PCR to determine the accuracy of NIPD RhD following two different DNA extraction protocols. The number of days from phlebotomy until freezing of plasma at the study site was recorded and defined as transport time.
NIPD RhD results of 972 specimens were analyzed according to transport time, which varied from a few hours to a maximum of 8 days (median 2 days). No decrease of cell-free fetal DNA was observed in samples with less than 6 days transport time. There was a pivotal trend to higher cycle threshold values in samples with ≥ 6 days transport time compared with those with ≤ 5 days.
Because only a few laboratories offer an NIPD RhD service, we suggest a maximal transport time of 5 days from phlebotomy until freezing at the testing laboratory.
在大规模开展胎儿 RhD 状态的无创性产前诊断（NIPD RhD）之前，明确样本运输的要求至关重要。本研究旨在确定用于 NIPD 的样本运输时间与母体外周血浆中胎儿 DNA 浓度之间的关系。
我们分析了之前使用实时 PCR 进行的一项研究中获得的定性和定量数据，以确定两种不同 DNA 提取方案下 NIPD RhD 的准确性。从采血到研究地点冷冻血浆的天数被记录下来，并定义为运输时间。
根据运输时间分析了 972 份标本的 NIPD RhD 结果，运输时间从数小时到最长 8 天不等（中位数为 2 天）。在运输时间少于 6 天的样本中，未观察到游离胎儿 DNA 的减少。与运输时间≤5 天的样本相比，运输时间≥6 天的样本中循环阈值值有升高的趋势。
由于只有少数实验室提供 NIPD RhD 服务，因此我们建议从采血到检测实验室冷冻的最长运输时间为 5 天。
