IUD Issues: Zero in with ultrasound
Displacement of an IUD from its expected location at the fundus of the uterus will almost always lead to some part of the IUD being embedded within the myometrium. Complete perforation may be difficult to identify by ultrasound because the surrounding bowel can hamper or prevent visualization. In these cases, other imaging modalities may be necessary.10,11
When a patient has an IUD and is referred for abnormal bleeding and pain, it is important to determine if the IUD position could be associated with the symptoms. Benacerraf et al. demonstrated that 75% of patients with an IUD referred with either pain or bleeding had a malpositioned IUD as compared to 35% of those without those symptoms.4 Braaten et al. demonstrated that malpositioned devices were present on 10.4% of scans among women having pelvic sonography for any indication and were usually in the lower uterine segment. In that study, approximately two-thirds of malpositioned IUDs were removed, resulting in a higher rate of pregnancy (due to non-initiation of another effective contraceptive method) as compared to those with normally positioned IUDs.15 In addition, malpositioned copper devices have decreased contraceptive efficacy if not located in the uterine fundus.16
Shipp et al. demonstrated that the endometrial cavity was narrower in patients with embedded or malpositioned IUDs as compared to those with normally positioned IUDs.7 Liang et al. demonstrated that women with larger transverse diameters of the coronal view of the uterus have a higher risk of IUD expulsion.17 Patients who are clinically suspected of having a small or large uterus may benefit from a pre-IUD insertion ultrasound to assess the maximal width of the endometrial cavity. This information may help determine the size of IUD that should be inserted or even whether an IUD is a reasonable option (Figure 10). Ultrasound may also be helpful for evaluation of IUD placement in women with uterine anomalies.
Further research is needed before an evidence-based recommendations can be made about IUD use in women with uterine anomalies.
IUDs have increasingly been inserted immediately postpartum, including following cesarean delivery. The advantage is a higher proportion of continued IUD use at 6 months postpartum when compared to interval IUD placement; however, approximately one-quarter are expelled or removed for malposition by 6 weeks postpartum.18,19