胎儿小脑幕下囊性病变较为常见,但由于胎儿小脑幕下解剖结构复杂,常规扫查准确率不高。文章应用三维超声对与小脑蚓部相关的Dandy-Walker综合征和Joubert综合征、Blake’s pouch囊肿及颅后窝蛛网膜囊肿4种囊性病变的诊断做了详细的阐述,对诊断与鉴别诊断胎儿脑部畸形的早期筛查提供重要的应用价值。 Fetal tentorial cystic lesions are more common, but due to the anatomy of the fetal tentorium complex, conventional scanning accuracy is not high. This article describes the diagnosis of Dandy-Walker syndrome associated with cerebellar vermis and Joubert syndrome, Blake’s pouch cyst and posterior fossa arachnoid cyst in four kinds of cystic lesions by three-dimensional ultrasonography. The diagnosis and differential diagnosis of fetal Early screening of deformities of the brain provides important application value.