Objective: Intrauterine devices (IUDs) are the most commonly used method of long-acting reversible contraception. IUD malpositions are described as expulsion, embedding, displacement, and perforation, which may cause contraception failure, organ injury, hemorrhage, and infection. The aim of the study was to evaluate the relationship between displacement and IUD positioning in the uterus, and uterine dimensions as measured using transvaginal ultrasonography. Materials and methods: Three-hundred and eighty-four patients who had TCu380A devices inserted at a tertiary hospital were evaluated at insertion and at 1 month, 3 months, and 6 months after insertion. At the insertion visit, demographic characteristics, history of menorrhagia, dysmenorrhea, previous IUD displacement, and obstetric history were recorded. Transvaginal ultrasonographic measurement of the uterine cavity, uterine length, uterine width, cervix length, cervix width, transverse diameter of the uterine cavity, the distance between the tip of the IUD and the fundus, and endometrium were measured to evaluate IUD displacement. Results: Sixteen of 384 patients had displacement. There were significant differences in times between last pregnancy outcomes and IUD insertion and dysmenorrhea history (p = 0.004 and p = 0.028, respectively). Among TCu380A users, women with 7.5 mm IUD endometrium distances had a higher risk for displacement with a sensitivity of 81% and specificity of 37.5% (AUC: 0.607, 95% CI 0.51-0.70). Women with uterus width less than 41.5 mm were more likely to have displacement with a sensitivity of 53.8% and a specificity of 75% (AUC: 0.673, 95% CI 0.60–0.75). Conclusion: IUD endometrium distance and uterus width are important parameters for displacement for TCu380A.