早孕期血清PAPP-A檢測聯合中孕期血清AFP、free β-HCG、uE3檢測對DS、ES的篩查效果

楊嵐,石錦平,吳曉,施楠,郭彩琴,趙麗

(南京醫科大學附屬無錫婦幼保健院, 江蘇無錫214002)

早孕期血清PAPP-A檢測聯合中孕期血清AFP、free β-HCG、uE3檢測對DS、ES的篩查效果

楊嵐,石錦平,吳曉,施楠,郭彩琴,趙麗

(南京醫科大學附屬無錫婦幼保健院,江蘇無錫214002)

目的觀察早孕期檢測血清PAPP-A聯合中孕期檢測血清AFP、free β-HCG、uE3對胎兒唐氏綜合征(DS)和愛德華氏綜合征(ES)的篩查效果。方法回顧性分析在我院行產前篩查且有隨訪結局的7 055例孕婦的臨床資料。所有孕婦早孕期檢測血清妊娠相關蛋白A(PAPP-A)和游離人絨毛膜促性腺激素β(Free β-hCG)，中孕期檢測血清甲胎蛋白(AFP)、free β-HCG、游離雌三醇(μE3)。設計3個DS、ES篩查方案。方案A納入指標為早孕期PAPP-A、Free β-hCG，方案B案納入指標為中孕期AFP、free β-HCG、μE3，方案C納入指標為早孕期PAPP-A和中孕期AFP、free β-HCG、μE3。用LifeCycle 4.0軟件綜合患者年齡、體質量、孕周等數據計算用三種方案篩查得出的患者DS、ES風險值。DS風險值>1/270為高風險，1/1 000～1/270為臨界風險；ES風險值>1/350為高風險，1/1 000～1/350為臨界風險。比較三種方案的DS高風險、DS臨界風險、ES高風險、ES臨界風險及陽性篩查結果檢出情況。胎兒出生者以胎兒是否確診DS、ES為金標準，終止妊娠者以羊水核型分析結果為金標準，計算三種方案篩查DS、ES的檢出率、假陽性率。結果方案C的DS高風險、DS臨界風險、篩查結果總陽性率均低于方案A、B(P均<0.05)。羊水穿刺染色體核型分析和胎兒出生后隨訪共發現DS患兒9例，其中方案A篩查結果陽性7例，檢出率77.8%，假陽性率3.95%；方案B篩查結果陽性6例，檢出率66.7%，DS假陽性率4.24%；方案C篩查結果陽性8例，檢出率88.9%，假陽性率1.80%。方案C的檢出率、假陽性率均優于方案A、B。羊水穿刺染色體核型分析和胎兒出生后隨訪共發現ES患兒2例，其中1例在3種篩查方案都得到了檢出，另1例ES患者用聯合方案得出了高風險值，ES檢出率聯合篩查方案均高于孕早期、孕中期方案。結論早孕期檢測血清PAPP-A聯合中孕期檢測血清AFP、free β-HCG、uE3對胎兒DS和ES的篩查效果優于早孕期檢測血清PAPP-A、free β-HCG或中孕期檢測血清AFP、free β-HCG、uE3。

唐氏綜合征；愛德華氏綜合征；早孕期；中孕期；妊娠相關蛋白A；人絨毛膜促性腺激素β；甲胎蛋白；雌三醇

Abstract:ObjectiveTo explore the screening efficiency about the first trimester screening of pregnancy-associated plasma protein A (PAPP-A) combined with the second trimester screening of alpha fetoprotein (AFP), free β-human chorionic gonadotropin (free β-HCG), uncojugated estriol (uE3) strategies for Down's Syndrome (DS) and Edwards' syndrome (ES).MethodsThe clinical data from 7 055 cases of pregnant women with pregnancy outcome, who underwent prenatal screening test, were retrospectively analyzed. The serum PAPP-A, free β-hCG in the first trimester, and AFP, free β-HCG, and uE3 in the second trimester were detected in all pregnant women. We designed three screening tests as three groups: projects A, B, and C. The risk evaluation of project A was serum free β-hCG and PAPP-A levels in the first trimester screening. Project B included free β-hCG, AFP, and uE3 levels in the second trimester. As for project C-so called the integrated serum test, included the serum PAPP-A levels in the first trimester, and AFP, β-hCG, and uE3 in the second trimester. The risks of DS and ES were evaluated by LifeCycle 4.0 software based on the age, weight and gestational week of gravidas. The cut-off value (high risk) and the intermediate risk value were >1/270 and 1/1 000-1/270 in DS, >1/350 and 1/1000-1/350 in ES, respectively. We compared the high risk rate, intermediate risk rate in both DS and ES as well as the total positive rates among the three screening tests mentioned above. The women who terminated pregnancy were identified by prenatal diagnosis via amniocentesis. Furthermore, those who did not terminate pregnancy were confirmed by the pregnancy outcomes, and were followed up based on karyotype of newborns. We evaluated screening efficiency of DS and ES such as the detection rate (DR) and false positive rate (FPR) among the three screening strategies.ResultsThe high risk and the intermediate risk in DS as well as the screening positive rate of the project C were significant lower than those of projects A and B, respectively (P<0.05) (neural tube defect were excluded). A total of 9 fetus with true DS were diagnosed via amniocentesis and follow-up pregnancy outcomes. In the project A, the number of high risk was 7, DR and FPR for trisomy 21 was 77.8% (7/9) and 3.95% (279/7 055), respectively. In the project B, the number of high risk was 6, DR and FPR for trisomy 21 was 66.7% (6/9) and 4. 24% (299/7 055), respectively. In the project C, DR and FPR for trisomy 21 was 88.9% (8/9) and 1.80% (127/7 055) , respectively. The DR and FPR for DS in the project C were both superior to those in the projects A and B (DR:P>0.05, FPR:P<0.05). We diagnosed two fetus with true ES through amniocentesis and follow-up pregnancy outcomes. Only one case was successfully detected by all three screening projects. The other case was detected as high risk in the combined screening test. The detection rate for ES in the project C was higher than those in both projects A and B.ConclusionThe screening efficiency about the first trimester screening of PAPP-A combined with the second trimester screening of AFP, free β-HCG, and uE3 for DS and ES is superior to both the first trimester double test (PAPP-A and free β-HCG) and the second trimester triple test including AFP, free β-HCG, and uE3.

Keywords: Down Syndrome; Edwards syndrome; the first trimester; the second trimester; pregnancy-associated plasma protein A; human chorionic gonadotropin-β; alpha fetoprotein; estriol

唐氏綜合征(DS，又名21三體綜合征)和愛德華氏綜合征(ES，又名18三體綜合征)是臨床常見的先天出生缺陷病。針對這類胎兒染色體疾病的產前篩查方案，現今國內應用最普遍的是中孕期血清學指標篩查方案[1～2]，該方法經濟簡便，對胎兒無創，可在一定程度上減少這類缺陷兒出生[3]，但其檢出率較低[4～5]。國外有研究顯示將早、中孕期血清學指標整合為一個方案，可將DS、ES檢出率提高到88%～95%[6，7]。但國內尚無同類文獻報道。本研究對2015年5月～2016年5月在我院規律產檢的7 055例單胎孕婦的臨床資料進行了回顧行分析，觀察早孕期檢測血清PAPP-A聯合中孕期檢測血清AFP、free β-HCG、uE3(聯合方案)對胎兒DS和ES的篩查效果。現報告如下。

1 資料與方法

1.1 臨床資料 選擇同期于我院產前診斷中心規律產檢且有完整妊娠結局隨訪結果的單胎妊娠孕婦共7 055例，預產年齡8～9歲(28.38±2.95歲)。均于早孕期(孕10～13+6周)和中孕期(15～20+6周)進行了產前血清學指標篩查。均無吸煙史，無胰島素依賴性糖尿病，無DS、ES兒分娩史。本研究已經我院醫學倫理委員會批準。孕婦或其家屬均簽署知情同意書，并填寫早、中孕期產前篩查申請單。

1.2 DS、ES篩查方法 ①方案A：孕10～13+6周抽取孕婦肘靜脈血3 mL，不抗凝，室溫靜置2 h后于3 500 r/min離心6 min后分離血清，-20 ℃儲存備檢。采用 芬蘭PerKin Elmer公司生產的1235全自動多標記儀、DELFIA時間分辨熒光法及配套試劑檢測血清妊娠相關蛋白A(PAPP-A)和游離人絨毛膜促性腺激素β(free β-hCG)水平。操作按試劑盒說明書進行。用Lifecycler 4.0軟件綜合患者年齡、體質量、孕周等數據計算患者用早孕期方案篩查DS、ES風險值。DS風險值>1/270為高風險，風險值1/1 000～1/270為臨界風險；ES風險值>1/350為高風險，1/1 000～1/350為臨界風險。②方案B：納入的血清學指標為孕中期(孕15～20+6周)血清甲胎蛋白(AFP)、free β-hCG和游離雌三醇(uE3)。其余同孕早期方案。③方案C：納入的血清學指標為孕中期血清AFP、free β-hCG、uE3和孕早期PAPP-A。其余同孕早期方案。

1.3 DS、ES篩查的準確性評價方法 對篩查出的高風險孕婦進行遺傳咨詢，建議其接受羊水穿刺進行胎兒染色體核型分析。孕婦胎兒出生者均進行隨訪確定胎兒是否患有DS或ES。胎兒出生者以胎兒是否確診DS、ES為金標準，終止妊娠者以羊水核型分析結果為金標準，計算三種方案篩查DS、ES的檢出率、假陽性率。

1.4 統計學方法 采用SPSS17.0統計軟件。率的比較采用χ2檢驗和Fisher確切概率法。P<0.05 為差異有統計學意義。

2 結果

2.1 三種方案篩查結果比較 三種方案篩查結果見表1。方案C的DS高風險、DS臨界風險率均低于方案A和B(P均<0.05)，而其ES高風險、ES臨界風險率無統計學差異(P均>0.05)；方案A和B的DS高風險、ES高風險、ES臨界風險率相比，P均>0.05。

表1 三種方案篩查結果[例(%)]

2.2 三種方案篩查結果準確性比較 羊水穿刺染色體核型分析和胎兒出生后隨訪共發現DS患兒9例(其中1例為易位型)，其中方案A篩查結果陽性7例，靈敏度77.8%，假陽性率3.95%；方案B篩查結果陽性6例，靈敏度66.7%，假陽性率4.24%；方案C篩查結果陽性8例，假陽性率1.80%。方案C的檢出率均高于方案A和B(P均<0.05)，假陽性率均低于方案A和B(P均<0.05)。見表2。

表2 三種方案篩查DS效果比較

2.3 不同篩查方案對11例胎兒非整倍體疾病的篩查風險值比較 詳見表1方案C篩查得出的DS、ES兒風險值均比方案A和B高。

3 討論

前已述及，現今產前篩查的各種篩查方案都有不同的檢出率和假陽性率，檢出率>80%且假陽性率<5%是比較理想的結果[8]。本研究結果顯示三種篩查方案的特異度都>95%，方案C的特異度最高；方案A、B、C篩查DS檢出率分別為77.8%、66.7%、88.9%，方案C的檢出率高于方案A、B。另外本研究方案B的DS檢出率與國內外報道相符[1，2]，方案A的檢出率略低于文獻報道的85%[4，5]，分析可能與未納入超聲指標頸項透明層厚度(NT)有關，研究顯示，如納入NT指標則有望將DS的檢出率提高到89%以上[9]。早孕篩查最大的優勢在于可使高風險孕婦在孕早期即通過絨毛染色體分析得到確診，以使真陽性孕婦及時終止妊娠，是目前發達國家較常用的篩查方案[10]。本研究方案A、B的DS高風險、DS臨界風險及總陽性結果檢出雖然比方案C多，但是檢出率低于方案C，假陽性率則高于方案C，與相關報道[11，12]相仿。

有研究顯示酌情篩查和早中孕全面整合篩查的假陽性率僅2%～3%，DS檢出率達到90%以上[7, 13]。但全面整合篩查需符合NT檢查要求，酌情篩查需將孕婦合理區分為高風險、臨界風險、低風險三類，雖然在篩查成本上較整合篩查更優[14]，但需確定該方案的各類風險范圍，不同實驗室不同地區的標準并不相同。此外，該方案和序貫篩查一樣，在早孕期的高風險孕婦需行絨毛穿刺加以確診，故限制了這兩類方案的廣泛應用，而整合篩查方案既可獲得較高的檢出率，又減少了經濟壓力和有創診斷的社會支出，在早孕期還緩解了孕婦的焦慮情緒，具備較好的成本效益值，在NT檢查和絨毛穿刺技術受局限地區，適于臨床推廣。本研究中確診的2例ES患兒，用方案A、B篩查僅有1例得到了高風險值，另1例經方案C篩查判定為高風險，可見方案C篩查較方案A、B增加了1例ES的檢出。并且方案A、B篩查出的1例ES患兒用方案C測算出的ES風險值高于方案A和B，體現出了方案C對ES良好的篩查價值，該優勢在國外學者的研究中也得以證實[15]。

本研究結果顯示，方案C可以減少陽性篩查結果數量(假陽性率)，從而減少羊水穿刺這種有創性檢查的數量。雖然臨床上還有一種敏感且無創的高通量測序技術通過對母血中的胎兒游離DNA進行測序對DS、ES進行篩查[16]，但目前其高昂的檢測成本限制了其普遍開展。本研究結果顯示 早孕期檢測血清PAPP-A聯合中孕期檢測血清AFP、free β-HCG、uE3對DS和ES體現出了良好的篩查效率，有助于減低患者經濟壓力和社會支出，性價比較高，適于臨床推廣。

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Screening efficiency about the first trimester screening of PAPP-A combined with the second trimester screening of AFP, free β-HCG, and uE3 strategies for Down's Syndrome and Edwards' syndrome

YANGLan,SHIJingping,WUXiao,SHINan,GUOCaiqin,ZHAOLi

(WuxiMaternalandChildHealthHospitalAffiliatedtoNanjingMedicalUniversity,Wuxi214002,China)

10.3969/j.issn.1002-266X.2017.35.006

R714.7

A

1002-266X(2017)35-0018-04

2017-03-14)

無錫市醫管中心面上項目(YGZXM1510)；無錫市科技發展基金項目(CSE31N1511)；江蘇省婦幼保健重點資助項目(201315)。

楊嵐(1979-),女，醫學碩士，副主任醫師, 主要研究方向為產前篩查、產前診斷。E-mail：lilylan5930@sina.com

趙麗(1978-)，女，醫學碩士，副主任醫師，主要研究方向為產前診斷、遺傳咨詢。E-mail：our163@163.com