Fetal Medicine Center, Department of Obstetrics and Gynecology, Clinica Las Condes, Santiago, Chile.
Prenat Diagn. 2013 Dec;33(13):1233-7. doi: 10.1002/pd.4235. Epub 2013 Oct 4.
The aim of this study was to determine whether choroid plexus morphology ('butterfly' sign) and biparietal diameter (BPD) are effective sonographic screening tools for holoprosencephaly (HPE) in the first trimester.
An axial view of the fetal head was obtained routinely to determine the presence of the 'butterfly' sign in pregnancies presenting for sonographic screening at 11-13 weeks of gestation. The same view was also used to obtain BPD measurements. The definitive diagnosis of HPE was established by the sonographic demonstration of an anterior cerebral monoventricular cavity and thalamic fusion.
During a 9-year study period, 11 068 live fetuses were screened. There were 11 cases of HPE (prevalence 1/1006); all of them were detected by demonstration of an absent 'butterfly' sign with no false-positive cases. The BPD was less than the 5th percentile in 40% of the cases.
The 'butterfly' sign appears to be a highly sensitive marker for HPE in the first trimester. On the other hand, BPD measurements had a lower sensitivity, implying that microcephaly is not a prominent first-trimester feature in these cases. Incorporation of the 'butterfly' sign into the first trimester anatomy scan is simple and can facilitate the identification of the vast majority of fetuses with HPE in the first trimester.
本研究旨在确定脉络丛形态（“蝴蝶”征）和双顶径（BPD）是否是孕 11-13 周行超声筛查的胎儿中无脑儿（HPE）的有效超声筛查工具。
常规获取胎儿头部的轴位视图以确定“蝴蝶”征的存在，这些孕妇是因超声筛查而就诊，妊娠时间为 11-13 孕周。同一视图还用于获取 BPD 测量值。通过超声显示单一前脑脑室和丘脑融合来明确诊断 HPE。
在 9 年的研究期间，对 11 068 例活胎进行了筛查。有 11 例 HPE（患病率 1/1006）；所有病例均通过“蝴蝶”征缺失来发现，无假阳性病例。40%的病例 BPD 小于第 5 百分位数。
“蝴蝶”征似乎是孕早期 HPE 的高度敏感标志物。另一方面，BPD 测量值的敏感性较低，这意味着这些病例中微小头并非突出的孕早期特征。将“蝴蝶”征纳入早孕期解剖筛查中很简单，可以有助于识别大多数 HPE 胎儿。
