Gross S J, Shulman L P, Tolley E A, Emerson D S, Felker R E, Simpson J L, Elias S
Department of Obstetrics and Gynecology, University of Tennessee, Memphis.
Am J Obstet Gynecol. 1995 Jan;172(1 Pt 1):83-7. doi: 10.1016/0002-9378(95)90088-8.
Risk of trisomy 18 in a fetus with ultrasonographic diagnosis of choroid plexus cysts and no other anomalies is controversial. Using our data and current literature, we performed a meta-analysis and estimated the positive predictive value of isolated choroid plexus cysts for trisomy 18.
Between Jan. 1, 1989, and Dec. 31, 1992, all women undergoing ultrasonographic examination at our institution were prospectively evaluated for fetal choroid plexus cysts and cytogenetic outcome. In addition, all reports dealing with fetal choroid plexus cysts obtained from MEDLINE (1983 through 1992) were assessed. Only prospective studies with > 10 cases of choroid plexus cysts were further evaluated to determine the total number of fetuses with choroid plexus cysts and otherwise normal sonograms. Frequency of aneuploidy was determined by analysis of our data and the included studies. To estimate the positive predictive value of choroid plexus cysts from trisomy 18, a theoretic 2 x 2 table was constructed with values available from the literature.
Eighty fetuses with choroid plexus cysts were identified in our unit. Of 74 fetuses with isolated choroid plexus cysts, there were no cases of trisomy 18. Meta-analysis identified 2 cases of trisomy 18 among 748 fetuses with isolated cysts (1/374). To derive a positive predictive value of isolated choroid plexus cysts for trisomy 18, we reviewed the literature and found a total of 50 fetuses with trisomy 18 who underwent ultrasonographic examination in the midtrimester. There were 3 cases of isolated choroid plexus cysts, and 12 of 50 (24%) had otherwise normal ultrasonographic results. Using a midtrimester incidence of 1 in 2461 for trisomy 18 (Hsu LYF. In: Milunsky A, ed. Genetic disorders of the fetus. 3rd ed. Baltimore: Johns Hopkins University Press, 1992: 155-210; Hook et al. Am J Hum Genet 1989; 45:855-61) and a prenatal prevalence of 0.95% for choroid plexus cysts (based on a review of the literature), we obtained a positive predictive value of 1 in 390.
On the basis of the risk for trisomy 18 obtained from our meta-analysis (1/374) and its close approximation to the estimated positive predictive value (1/390), our data do not support the routine offering of invasive prenatal cytogenetic testing in cases of isolated choroid plexus cysts.
超声诊断为脉络丛囊肿且无其他异常的胎儿发生18三体综合征的风险存在争议。利用我们的数据和当前文献，我们进行了一项荟萃分析，并估计了孤立性脉络丛囊肿对18三体综合征的阳性预测值。
在1989年1月1日至1992年12月31日期间，对在我们机构接受超声检查的所有孕妇进行前瞻性评估，以了解胎儿脉络丛囊肿和细胞遗传学结果。此外，对从MEDLINE（1983年至1992年）获得的所有关于胎儿脉络丛囊肿的报告进行了评估。仅对超过10例脉络丛囊肿病例的前瞻性研究进行进一步评估，以确定有脉络丛囊肿且超声检查结果正常的胎儿总数。通过对我们的数据和纳入研究的分析确定非整倍体的频率。为了估计18三体综合征中脉络丛囊肿的阳性预测值，构建了一个理论上的2×2表格，并使用文献中的可用值。
我们单位共识别出80例有脉络丛囊肿的胎儿。在74例孤立性脉络丛囊肿胎儿中，无18三体综合征病例。荟萃分析在748例孤立性囊肿胎儿中发现2例18三体综合征（1/374）。为了得出孤立性脉络丛囊肿对18三体综合征的阳性预测值，我们查阅了文献，发现共有50例18三体综合征胎儿在孕中期接受了超声检查。其中有3例孤立性脉络丛囊肿，50例中有12例（24%）超声检查结果正常。利用18三体综合征的孕中期发病率为1/2461（Hsu LYF。载于：Milunsky A主编。胎儿遗传性疾病。第3版。巴尔的摩：约翰霍普金斯大学出版社，1992：155 - 210；Hook等人。《美国人类遗传学杂志》1989；45：855 - 61）以及脉络丛囊肿的产前患病率为0.95%（基于文献综述），我们得出阳性预测值为1/390。
基于我们的荟萃分析得出的18三体综合征风险（1/374）及其与估计的阳性预测值（1/390）的接近程度，我们的数据不支持对孤立性脉络丛囊肿病例常规提供侵入性产前细胞遗传学检测。
