研究正常胎儿小脑表面叶裂随孕周的变化规律并建立孕16~32周正常胎儿小脑叶裂数目参考值。

选取2019年6月至2020年12月在南方医科大学附属深圳妇幼保健院行产前超声检查无结构异常的644名妊娠12~32周的单胎孕妇，按孕周分为2个时间段观察：孕12~15周为阶段1，孕16~32周为阶段2，在二维图像上观察原裂、水平裂的显示情况并计数孕16~32周小脑原裂之前、原裂与水平裂之间、水平裂之后的叶裂数目及总数目，并分析其形态变化。随机抽取40名阶段2胎儿行叶裂数目两测量者间的组内相关系数（ICC）分析；建立阶段2胎儿小脑叶裂数目的参考值范围，采用Spearman相关行叶裂数目与孕周的相关性分析并建立拟合方程。

叶裂数目的计数两观察者之间的重复性检验一致性较好（ICC=0.969，P＜0.001）。各散点图显示正常胎儿小脑原裂之前、原裂与水平裂之间、水平裂之后叶裂数目及总数目与孕周呈正相关（r=0.863、0.698、0.831、0.932，P均＜0.001）。建立了各区域叶裂数目及总数目与孕周的二次多项式回归方程，原裂之前、原裂与水平裂之间、水平裂之后叶裂数以及总数目与孕周的回归方程分别为：Y=0.974X-0.014X ² -12.65，Y=0.362X-0.005X ² -4.843，Y=-0.125X+0.006X ² +0.285，Y=1.800X-0.024X ² -22.904。

利用产前超声可以较好地观察胎儿小脑表面叶裂并对其发育情况作出初步评估。胎儿小脑表面叶裂数目的正常参考值以及形态变化规律能为产前超声评估小脑皮质发育作出参考。

To determine the variation of cerebellar fissure with gestational weeks in normal fetuses and to establish the numeric reference range for fetal cerebellar fissure at 16-32 weeks.

From June 2019 to December 2020, 644 singleton fetuses with no structural abnormalities diagnosed by prenatal ultrasound were selected as study subjects at Shenzhen Maternal and Child Health Hospital, and divided into two groups: fetuses at 12-15 weeks of gestation and those at 16-32 weeks. The primary fissure and horizontal fissure in two-dimensional images were observed, the number of cerebellar fissures at 16 to 32 weeks of gestation counted, and the morphological changes analyzed. Forty fetuses were randomly sampled and tested for repeatability between two observers. The normal numeric reference range for cerebellar fissure between 16 and 32 weeks of gestation was established. The correlation between the number of cerebellar fissures and gestational age was analyzed by Spearman correlation, and fitting equations were then established.

There was no significant difference in the repeatability test between the two observers. The scatter plots showed that the number of cerebellar fissures were positively correlated with gestational age (r=0.863, 0.698, 0.831, and 0.932, P＜0.001). Quadratic polynomial regression equations were each fitted to the models. The regression equations for the number of cerebellar fissures in three different regions and the total number of fissures were Y=0.974X-0.014X ² -12.65, Y=0.362X-0.005X ² -4.843, Y=-0.125X+0.006X ²+0.285, and Y=1.800X-0.024X ² -22.904, respectively.

Prenatal ultrasound can be used to observe and evaluate the development of fetal cerebellar fissures. The numeric reference range and morphological changes of the normal fetal cerebellar fissures may be useful for prenatal evaluation of the development of the cerebellar cortex.