ABSTRACT
BACKGROUND: Intrauterine devices are currently one of the leading forms of reversible contraception in the world. However, in approximately 10-25% of women, intrauterine devices can become malpositioned, leading to consequences including pain, bleeding, as well as possible decreased contraceptive efficacy. OBJECTIVE: We sought to determine whether certain reproductive and uterine characteristics are associated with an increased risk of intrauterine device malposition. We hypothesized that anatomical characteristics such as the presence of any uterine anomalies, particularly congenital anomalies and fibroids that may lead to cavitary distortion, would be associated with a higher incidence of intrauterine device malposition. MATERIALS AND METHODS: We conducted a retrospective case-control study in an academic medical center. All patients presenting for scheduled ultrasound appointments for gynecologic indication between June 2004 and February 2016 were included (1,253 ultrasound reports identified). Of these, 236 demonstrated malpositioned intrauterine devices. With a control group of 281 patients with normal intrauterine device location, a total of 517 patients were included in the study. Transabdominal and transvaginal ultrasounds were performed followed by 3-dimensional rendering (as per our institution's protocol for patients with intrauterine devices) using Voluson 730 and Voluson E8 ultrasound machines. Demographic and reproductive characteristics, indication for ultrasound, intrauterine device, and uterine characteristics were all extrapolated from the electronic medical record. χ2 Tests were performed for categorical variables. Generalized linear models for Poisson distributed variables, and multiple logistic regression were used to ascertain significant independent predictors of IUD malposition. Ninety-five percent confidence intervals and effect sizes were calculated, and P < .05 was considered statistically significant. RESULTS: In this study, we found a cumulative IUD malposition rate of 19%. In patients with malpositioned intrauterine devices, there was increased incidence of retroflexed uterine positions (7.6% vs 1.8%, P = .001), and all uterine anomalies (this includes septate and bicornuate uteri and fibroids, 31.9% vs 23.5%, P = .02) compared with controls. The anterior midline uterine position was more commonly noted in controls (28.5% vs 11%, P < .001). A higher total number of fibroids was noted in the malpositioned group (3.7 vs 1.8, P = .01); however, fibroid size was not statistically significant. In particular, there was an increased incidence of submucosal fibroids in women with malpositioned intrauterine devices (P = .01). Multivariable logistic regression revealed that anterior midline position (odds ratio [OR], 0.33; 95% confidence interval [CI], 0.20-0.57) and absence of uterine anomalies (OR, 0.59; 95% CI, 0.38-0.93) were factors associated with a lower risk of IUD malposition; whereas vaginal bleeding (OR, 2.25; 95% CI, 1.38-3.67), pain (OR, 2.85; 95% CI, 1.84-4.44), or missing IUD strings at time of presentation (OR, 3.58; 95% CI, 1.88-6.82) were associated with an increased risk of malposition. CONCLUSION: Retroflexed uterine positions and all uterine malformations are associated with higher incidence of malpositioned intrauterine devices. Presence of increased number of fibroids and specifically submucosal fibroids showed a positive association with intrauterine device malposition, as did symptoms of bleeding, pain, and missing IUD strings at time of presentation. These findings pertain to women presenting for gynecologic ultrasound evaluation and may not be generalizable to all women with IUDs.
