胎儿脑中线结构异常的产前超声诊断

Ultrasound for prenatal diagnosis of fetal midline brain abnormalities

目的探讨产前常规超声检查对胎儿脑中线结构异常的临床应用价值。方法回顾性分析经常规超声检查怀疑有脑中线结构异常的胎儿178例，孕妇年龄19-43岁，平均年龄30．7岁，孕周14-38周。平均孕周28．4周。所有胎儿均经腹扫查．应用二维或三维超声扫查模式．总结并归纳其声像图特征。超声怀疑有脑中线结构异常的胎儿可行MRI检查或染色体检查，经生后随访或尸检证实超声检查结果。计算超声和MRI诊断胎儿脑中线结构异常的阳性预测值，采用卡方检验进行统计学分析。结果产前超声诊断胎儿脑中线结构异常178例，其中前脑无裂畸形27例，胼胝体发育不全53例，单纯透明隔腔缺如2例．Dandy-Walker畸形9例，小脑蚓部发育不良14例，巨大枕大池73例。178例胎儿失访9例．经生后随访或尸检证实的169例胎儿中，真阳性数为145例；178例胎儿中共有73例接受MRI检查，阳性60例，其中真阳性数为53例；超声和MRI诊断胎儿脑中线结构异常的阳性预测值分别为85．8％及88-3％．二者间差异无统计学意义（P〉0．05）。结论超声检查安全有效．方便省时，对胎儿脑中线结构异常确诊率较高．是产前筛查胎儿脑中线结构异常的可靠方法。

Objective To evaluate the clinical application of ultrasound as a routine scanning method for fetal midline brain abnormalities. Methods A total of 178 cases with fetal midline brain abnormalities suspected by ultrasound were analyzed retrospectively. The maternal age was 19 - 43 years old, with a mean maternal age of 30.7. The gestational age was 14 - 38 weeks, with a mean gestational age of 28.4 weeks. All the fetuses underwent transabdominal ultrasound, and the two-dimensional and/or three-dimensional ultrasound was used. The positive predictive value（PPV） of ultrasound and magnetic resonance imaging（MRI） were calculated, Chi-square test was performed to determine PPV of ultrasound, which was significantly different from that of MRI. Results The 178 fetus with fetal midline brain abnormalities were examined prenatally by ultrasound. Among these cases, there were 27 cases of holoprosencephaly, 53 cases of corpus callosum agenesis, 2 cases of isolated absence of septum pellucidum, 9 cases of Dandy-Walker malformation, 14 cases of cerebellar vermis hypoplasia and 73 cases of megacysterua magna. Nine cases were lost follow-up, and 169 cases were confirmed by autopsy or follow-up, 145 cases were true positive among the cases suspected by ultrasound; 73 fetuses underwent MRI, and 60 fetuses had positive results, 53 of them were true positive. The PPV of ultrasound and MRI were 85.8 % and 88.3 %, respectively. The PPV of ultrasound for fetal midline brain abnormalities showed no significant difference from that of MRI（P 〉 0.05）. Conclusion It is demonstrated that ultrasound examination is a safe, effective, convenient and time-saving method to screen fetal midline brain abnormalities with high detection rate.