Objective:To explore the influencing factors of uterine myometrial and parauterine venous plexus reflux during transvaginal four-dimensional contrast-enhanced hysterosalpingography, which will help reduce and avoid the occurrence of reflux and improve the accuracy of diagnosis.Methods:A total of 306 infertile patients who underwent transvaginal four-dimensional contrast-enhanced hysterosalpingograph from June 2016 to June 2017 in the Third Affiliated Hospital of Guangzhou Medical University were retrospectively enrolled. The ultrasonographic characteristics were reviewed and the correlations between reflux and endometrial thickness, days after menstruation, intrauterine operation history and patency of fallopian tube were analyzed.Results:The incidence of countercurrent during four-dimensional contrast-enhanced hysterosalpingography was 14.71%. The chi-square test showed that the endometrial thickness and the days after menstruation had statistically significant effects on the incidence of reflux ( P=0.031 and <0.001, respectively). There were no statistically significant effects of intrauterine operation history and patency of the fallopian tube on the incidence of reflux ( P=0.610, 0.137). Logistic regression analysis showed that the incidence of reflux was associated with endometrial thickness ( B=-1.171, P<0.001) and the days after menstruation ( B=0.439, P=0.015). Conclusions:Transvaginal ultrasound measurement of endometrial thickness before angiography and selection of appropriate examination time according to the menstrual cycle can effectively reduce the incidence of reflux, and adverse reactions, and improve the accuracy of four-dimensional contrast-enhanced hysterosalpingography.