Abstract： Objective:By formulating and validating a nomogram for differentiating in-trauterine adhesions(IUA)based on clinical characteristics and three-dimensional transvaginal ultrasound(3D-TVS),to improve the accuracy of 3D-TVS diagnosing IUA,and to reduce the rate of misdiagnosis and missed diagnosis of IUA.Methods:A total of 607 subjects who under-went 3D-TVS and hysteroscopy at Sun Yat-sen Memorial Hospital for suspected IUA were en-rolled between June 2017 to July 2021.The clinical characteristics and preoperative 3D-TVS characteristics of all subjects were all collected.Firstly,the collected samples were randomly di-vided into the training set and the validation set by SPSS at a ratio of 7∶3.In the training set,the logistic regression analysis explored the relationship between clinical characteristics,3D-TVS characteristics and IUA.On the basis of logistic regression analysis,the variables with sig-nificant statistical differences were selected to establish a nomogram.In validation set,receiver operating characteristic(ROC)curve,clinical calibration curve,Hosmer-Lemeshow test,deci-sion curve analysis(DCA),and clinical impact curve(CIC)were used to evaluate the perform-ance of the nomogram.Results:We finally included 607 samples,of which 401 were diagnosed with IUA by hysteroscopy and 206 were diagnosed with non-IUA.At the beginning,607 samples were divided into a training set(n=420)and a validation set(n=187).In the training set,age,frequency of previous first-trimester procedure,frequency of previous second trimester and late procedure,uterine cavity area(cm2),interrupted endometrial echogenicity,and left or right lateral indentation angle≤130 degrees differed significantly between IUA and non-IUA groups(P<0.05).In validation set,the area under the curve(AUC)of the ROC curve indicated that the nomogram had the ability to accurately predict and diagnose IUA.Both the Hosmer-Leme-show test and the clinical calibration curve showed that the nomogram had high calibration abil-ity.Both DCA and CIC showed that the model had high clinical value.Conclusions:The differ-ential nomogram was established based on the clinical characteristics and 3D-TVS characteris-tics.It was able to feasibly distinguish IUA before hysteroscopy.Age,frequency of previous first-trimester procedure,frequency of previous second trimester and late procedure,uterine cavity ar-ea(cm2),interrupted endometrial echogenicity and left or right lateral indentation angle≤130 degree were significant variables for predicting IUA.