探討非侵入性母血胎兒染色體檢測與羊膜穿刺術在現今產前診斷上之運用

Abstract

人類的懷孕總是存在產生部分異常胚胎或胎兒的機率，因而過去發展出羊膜穿刺術及絨毛膜取樣術等侵入性技術，以取得胎兒或絨毛膜細胞直接診斷是否有染色體的異常，但是侵入性檢查總是有少數機率有流產、感染、破水等風險存在，因此後來發展出第一孕期與第二孕期唐氏症篩檢，先行篩檢出可能的胎兒染色體異常的高風險個案，再行羊膜穿刺術，在台灣同時也以高齡懷孕為胎兒染色體異常的高風險群，皆施行羊膜穿刺術，然而僞陽性率偏高，許多實際上正常的個案，因為唐氏症篩檢為高風險而接受侵入性的羊膜穿刺術，因此最近又發展出非侵入性母血胎兒染色體檢測（NIPT）的篩檢技術，以期待能到更精確的篩檢結果，以減少偽陽性的結果，進而減少侵入性檢查施術的機會。 本研究取樣100例因故施行羊膜穿刺術的孕婦，其中有2名孕婦為雙胞胎，所以共有102例胎兒，然其中僅2例胎兒為染色體異常個案，僅佔1.96%。另取樣8例接受NIPT的案例，有1例NIPT顯示為高風險，經羊膜穿刺術取羊水胎兒細胞分析也證實為染色體異常個案。 產前診斷的技術日新月異，若將NIPT與第一孕期唐氏症篩檢的超音波檢查組合在一起，可以提供孕婦高敏感度、高特異性與高安全性的產前胎兒異常的篩檢方式，如此羊膜穿刺術的實施量將會減少很多，也會大量減少因實施侵入性檢查而導致流產、感染、破水等等事件的發生。

There are existing risks to have fetal chromosome abnormality in the world. Amniocentesis is used to obtain fetal cells to analyze fetal chromosome. This invasive procedure leads to some risks, including miscarriage, rupture of amniotic membrane, infection, and other complications. Therefore, some non-invasive screening methods were developed during recent two decades, such as second trimester Down screening and first trimester Down screening. And there is a recent technique named Non-Invasive Prenatal Test (NIPT), which is developed to decrease the chances to undergo amniocentesis. In this study, 100 cases of pregnant women with 102 fetuses underwent amniocentesis, but just 2 cases had abnormal fetal chromosome. This means that the previous indications for amniocentesis reveal low positive predictive value for fetal chromosome abnormality. On the other hand, 8 cases of pregnant women underwent NIPT. High risk was reported for one case. The case was confirmed with amniocentesis, and was proven to have fetal chromosome abnormality. Developing prenatal screening methods to reduce the chances of undergoing invasive procedure is important to prenatal diagnosis.