Incidence and Risk Factors for a Malpositioned Intrauterine Device Detected on Three-Dimensional Ultrasound Within Eight Weeks of Placement

Objectives: To estimate the incidence of intrauterine device (IUD) malpositioning detected on three-dimensional (3D) transvaginal ultrasound within 8 weeks of placement and identify risk factors for malpositioning. Methods: Retrospective study of women who had an IUD placed at a large obstetrics and gynecology practice from January 1, 2015, to December 31, 2020. All patients underwent two-dimensional ultrasound at the time of insertion and routine three-dimensional ultrasound within 8 weeks. Baseline characteristics and potential risk factors were compared between women with correctly positioned and malpositioned IUDs. Odds ratios were calculated by logistic regression to identify risk factors independently associated with malpositioning. Results: A total of 763 IUD placements were included, and 127 malpositioned IUDs were identified representing an overall rate of malpositioning of 16.6% (95% confidence interval [CI] 14.0–19.3) with 8.8% (95% CI 6.8–10.8) requiring removal. Patients with malpositioned IUD had higher rates of morbid obesity (13.4% versus 3.8%, adjusted odds ratio [aOR] 2.46, 95% CI 1.10–5.50), prior uterine window or rupture (9.0% versus 2.2%, aOR 2.78, 95% CI 1.06–7.30), copper IUD placement (64.2% versus 47.4%, aOR 1.99, 95% CI 1.31–3.03), and symptoms such as bleeding or pain at follow-up (35.8% versus 20.1%, aOR 2.58, 95% CI 1.67–3.98). Parity, breastfeeding, difficult insertion, and uterine size and positioning were not significant. Conclusions: The incidence of malpositioned IUD within 8 weeks of placement on 3D ultrasound is 16.6%, with 8.8% requiring removal. Significant risk factors for malpositioning include morbid obesity, prior uterine window or rupture, and copper IUD placement. These findings support the importance of routine follow-up 3D ultrasound after seemingly successful IUD placement.