Objective To evaluate the association of the size of thyroid nodules and the diagnostic value of repeat fine needle aspiration cytology(FNAC) in diagnose of thyroid nodules.Methods One hundred and forty-three thyroid nodules in one hundred and thirty-five patients with repeat FNAC and thyroidectomy were retrospectively analyzed.The nodules were divided into three groups according to the largest diameter(L):GroupA,L＜0.5 cm;GroupB,0.5 cm≤L≤1.0cmandGroupC,L＞1.0cm.Yield of FNACs were divided into six levels according to the classification criteria of the Bethesda system,and Level Ⅰ,Ⅲ,Ⅳ,Ⅴ were defined as the indefinite cytological diagnosis.Results The diagnostic rate of repeat FNAC was obviously higher in group B compared with group A and group C,with significantly statistical difference (P ＜0.05).The risk of malignancy for persistently indefinite diagnostic aspirates after repeat FNAC was significantly reduced with statistical difference from the initial indefinite diagnostic aspirates in group B (P ＜0.05),while there was no statistical difference between group A and group C (P＞0.05).The diagnostic accuracy of repeat FNAC in group B was significantly higher than that in group A(P ＜0.05),but not in group C (P ＜0.05).Conclusions The repeat FNAC has a higher efficiency in those nodules with a largest diameter between 0.5 cm and 1.0 cm,and a repeat FNAC can be suggested.

Infant nutritional status evaluation is a basic experimental skill in the experimental teaching of nutrition and food hygiene. The construction of this virtual simulation experiment can solve the problems of activeness and poor coordination of infants and young children in the actual operation of the experiment. And based on the application of this virtual simulation project, the experimental teaching method of preventive medicine was explored. This experiment adopted online and offline mixed teaching method, which enriches teaching measures and strengthens the standardized process of infant nutritional status evaluation. After 3 semesters of practice from spring 2018 to spring 2020, the proportion of students who achieved excellent grades was 30.09% (34/113), 56.02% (279/498) and 66.79% (1 080/1 617), respectively, which increased significantly year by year ( Ptrend < 0.001). Among all the 2 228 students, 1 983 students (89%) believed that this experimental teaching could better cultivate the ability of autonomous learning. Through the study of virtual simulation experiments, students have improved their subjective initiative, and laid a foundation for the improvement of students' overall quality and the requirements of school elite education.