胎儿颅后窝池异常的超声评价及临床意义

Clinical significance of ultrasonography in evaluating the abnormality of fetal cisterna magna

目的探讨胎儿颅后窝池（CM）异常的产前超声表现及其临床转归。方法孕中、晚期进行胎儿系统检查时于小脑横切面测量CM深度，对深度2～10mm外的129例胎儿进行随访观察和总结分析。结果随访CM深度异常的胎儿中CM缩小或消失39例，均为畸形病例，包括脊柱裂36例，小头畸形2例，Arnold—ChiariII型畸形1例；CM扩大90例，随访证实正常55例，治疗性引产1例，畸形引产34例。扩张组中，Dandy-Walker畸形合并18-三体6例。随CM扩张程度不同，畸形发生率的差异有统计学意义（P〈0．01）。结论产前超声检查应重视CM深度的改变，CM消失或缩小高度提示胎儿畸形；CM扩张是胎儿系统检查及定期复查的指征，单发且无进行性扩张者预后较好。

Objective To study the prenatal sonographic characteristics of the abnormality of cistema magna（CM）and the corresponding clinical outcomes. Method During the 2nd or 3rd trimester, the depth of CM was measured by ultrasound and the abnormality could be diagnosed if the depth was out of the standard of 2 mm to 10 mm. For each abnormal case, a thorough evaluation of fetal anatomy was performed and follow-up was done after birth. Results One hundred and twenty-nine fetuses were diagnosed as depth anomaly and were followed up. Among them, 39 fetuses were clinicaUy diagnosed as malformations, complicating with disappearance or diminishment of CM. Among the 90 fetuses with enlarged CM, 34 were clinically diagnosed as malformations and 55 were found no abnormality through follow-up,the rest 1 fetus was intermitted for therapy. In the Dandy-Walker malformation, there were 6 fetuses complicaring with trisomy 18. With the increase of CM expansion, the incidence rate of malformations was significantly increased （ P 〈 0.01）. The abnormality of CM is valuable in prenatal sonographic diagnosis. The CM disappearance highly indicates the abnormality of fetuses. Enlarged CM is the indication for a further systematic sonographic exam and follow-up.