Revello M G, Sarasini A, Zavattoni M, Baldanti F, Gerna G
Viral Diagnostic Service, IRCCS Policlinico San Matteo, Pavia, Italy.
J Med Virol. 1998 Sep;56(1):99-103. doi: 10.1002/(sici)1096-9071(199809)56:1<99::aid-jmv16>3.0.co;2-r.
Two major variables may cause false-negative results in prenatal diagnosis of congenital human cytomegalovirus (HCMV) infection: sensitivity of the techniques(s) used; and time elapsed between maternal infection and antenatal testing. Previous results indicated that rapid HCMV isolation from amniotic fluid samples and viral DNA detection in amniotic fluid by nested polymerase chain reaction (nPCR) had comparable levels of sensitivity (69.2% and 76.9%, respectively). The nPCR protocol was reviewed following two additional false-negative antenatal diagnosis in a twin pregnancy during which two procedures were performed at 18 and 23 weeks of gestation, respectively. In the new assay, multiple (instead of single) and 100 (instead of 20) microliters amniotic fluid aliquots were individually amplified and tested by nPCR. By using this approach, low DNA levels (1-10 genome equivalents) were detected in 1-5/8 replicates of amniotic fluid samples taken from both twins during both procedures. In addition, viral DNA was detected in 5/6 replicates from two amniotic fluid samples still available from two previous false-negative cases. However, nPCR on multiple amniotic fluid replicates did not anticipate positive prenatal results in a retrospective case, which required two procedures for correct diagnosis and, when prospectively employed, did not avoid one additional false-negative prenatal diagnosis 8 weeks after maternal infection. Thus, delayed intrauterine transmission of the infection may be a potential cause of false-negative results. However, the combination of a very sensitive technique with appropriate timing of prenatal testing can substantially increase the reliability of prenatal diagnosis results.
在先天性人类巨细胞病毒（HCMV）感染的产前诊断中，有两个主要变量可能导致假阴性结果：所使用技术的敏感性；以及母体感染与产前检测之间的时间间隔。先前的结果表明，从羊水样本中快速分离HCMV以及通过巢式聚合酶链反应（nPCR）检测羊水中的病毒DNA具有相当的敏感性水平（分别为69.2%和76.9%）。在一例双胎妊娠中，分别在妊娠18周和23周进行了两次检测，出现了另外两例假阴性产前诊断后，对nPCR方案进行了审查。在新的检测方法中，对多个（而非单个）100微升（而非20微升）的羊水等分试样分别进行扩增，并通过nPCR进行检测。通过这种方法，在两次检测过程中从两个双胞胎采集的羊水样本的1 - 5/8次重复检测中检测到了低DNA水平（1 - 10个基因组当量）。此外，在之前两例假阴性病例中仍可获得的两份羊水样本的5/6次重复检测中检测到了病毒DNA。然而，对多个羊水重复样本进行nPCR在一例回顾性病例中并未预测出阳性产前结果，该病例需要两次检测才能正确诊断，并且在前瞻性应用时，也未能避免在母体感染8周后出现另外一例假阴性产前诊断。因此，感染的宫内传播延迟可能是假阴性结果的一个潜在原因。然而，将非常敏感的技术与适当的产前检测时间相结合，可以大幅提高产前诊断结果的可靠性。
