Ghidini A, Strobelt N, Locatelli A, Mariani E, Piccoli M G, Vergani P
Department of Obstetrics and Gynecology, Georgetown University Medical Center, Washington, DC 20007, USA.
Am J Obstet Gynecol. 2000 Apr;182(4):972-7. doi: 10.1016/s0002-9378(00)70356-5.
The significance of isolated choroid plexus cysts found by ultrasonographic scan during the second trimester as a marker for trisomy 18 is still debated. We analyzed our data and reviewed the series published in the English-language literature to calculate the likelihood ratio of trisomy 18 in the presence of isolated choroid plexus cysts; that is, the factor by which the individual risk of trisomy 18 is increased in the presence of isolated choroid plexus cysts.
Likelihood ratios were calculated as ratio of the sensitivity to the false-positive rate. Sensitivity was defined as the rate of isolated choroid plexus cysts detected at midgestation among fetuses with trisomy 18. False-positive rate was defined as the rate of choroid plexus cysts detected at midgestation in the population without trisomy 18. The sensitivities of all published series reporting rates of choroid plexus cysts at the time of the first ultrasonographic examination between 14 and 24 weeks' gestation in populations with trisomy 18 and in low-risk populations were included in the analysis. To these we added all cases of trisomy 18 diagnosed at our institution during the period January 1, 1988, through June 30, 1998, in which prenatal ultrasonographic examination was performed between 14 and 24 weeks' gestation.
The prevalence of second-trimester ultrasonographic detection of isolated choroid plexus cysts among fetuses with trisomy 18 was 6.7% (13/194), whereas that in the population without trisomy 18 was 0.9% (752/79,583). The likelihood ratio associated with isolated choroid plexus cysts was therefore 7.09 (95% confidence interval, 3.97-12.18).
The presence of isolated second-trimester choroid plexus cysts increases the base risk of trisomy 18 by a factor of 7.09. This likelihood ratio can be multiplied by the risk calculated according to maternal age to obtain the individual risk of trisomy 18 and thus permit more accurate counseling of the patient.
孕中期超声扫描发现的孤立性脉络丛囊肿作为18三体综合征标志物的意义仍存在争议。我们分析了我们的数据，并回顾了英文文献中发表的系列研究，以计算存在孤立性脉络丛囊肿时18三体综合征的似然比；即，存在孤立性脉络丛囊肿时个体患18三体综合征风险增加的因素。
似然比计算为敏感度与假阳性率之比。敏感度定义为孕中期在18三体综合征胎儿中检测到的孤立性脉络丛囊肿的发生率。假阳性率定义为在无18三体综合征的人群中孕中期检测到的脉络丛囊肿的发生率。分析纳入了所有已发表系列研究中，报告孕14至24周首次超声检查时18三体综合征人群和低风险人群中脉络丛囊肿发生率的敏感度。我们还纳入了1988年1月1日至1998年6月30日期间在我们机构诊断的所有18三体综合征病例，这些病例在孕14至24周进行了产前超声检查。
孕中期超声检测到的18三体综合征胎儿中孤立性脉络丛囊肿的患病率为6.7%（13/194），而在无18三体综合征的人群中为0.9%（752/79,583）。因此，与孤立性脉络丛囊肿相关的似然比为7.09（95%置信区间，3.97 - 12.18）。
孕中期孤立性脉络丛囊肿的存在使18三体综合征的基础风险增加了7.09倍。这个似然比可以乘以根据母亲年龄计算出的风险，以获得个体患18三体综合征的风险，从而为患者提供更准确的咨询。
