CT imaging of intrauterine devices (IUD): expected findings, unexpected findings, and complications

Intrauterine devices (IUDs) are a commonly used form of long-acting reversible contraception, which either contain copper or levonorgestrel to prevent pregnancy. Although symptomatic patients with indwelling IUDs may first undergo ultrasound to assess for device malposition and complications, IUDs are commonly encountered on CT in patients undergoing evaluation for unrelated indications. Frequently, IUD malposition and complications may be asymptomatic or clinically unsuspected. For these reasons, it is important for the radiologist to carefully scrutinize the IUD on any study in which it is encountered. To do so, the radiologist must recognize that normally positioned IUDs are located centrally within the uterine cavity. IUDs are extremely effective in preventing pregnancy, though inadvertent pregnancy risk is higher with malpositioned IUDs. Presence of fibroids or Mullerian abnormalities may preclude proper IUD placement. Radiologists play an important role in identifying complications when they arise and special considerations when planning for an IUD placement. There is a wide range of IUD malposition, affecting IUDs differently depending on the type of IUD and its mechanism of action. IUD malposition is the most common complication, but embedment and/or partial perforation can and can lead to difficulty when removed. Retained IUD fragments can result in continued contraceptive effect. Perforated IUDs do not typically cause intraperitoneal imaging findings.