Risk factors of uterine perforation include clinician inexperience in IUD placement, an immobile uterus, a retroverted uterus, and the presence of a myometrial defect.4 Heinemann et al2 also suggested that breastfeeding and IUD placement soon after a delivery (≤36 weeks) are independent risk factors, and the presence of both factors has an additive increase in risk of perforation.
Primary rupture of the uterus has been reported at the time of IUD insertion, but secondary or delayed rupture is more common and seems to be due to the spasms of the uterus.5 Although 85% of perforations do not affect other organs, the remaining 15% lead to complications in the adjacent visceral organs.6 The most frequent sites of migration are to the omentum (26.7%), pouch of Douglas (21.5%), large bowel (10.4%), myometrium (7.4%), broad ligament (6.7%), abdominal cavity (5.2%), adhesion to ileal loop serosa (4.4%) or large bowel serosa (3.7%), and mesentery (3%).7 Rare sites are to the appendix, abdominal wall, ovary, and bladder.7
Intrauterine device migration should be suspected in patients who become pregnant after IUD placement (as was the case for our patient), when the “threads” or string cannot be located while attempting to remove an IUD, or when a patient has an “expulsed” IUD without observation of the device thereafter. Even though expulsion of the device happens in approximately 8 per 1,000 insertions, uterine perforation is also a possibility in the case of a “lost” IUD.8 When a lost IUD is suspected, a pelvic examination should be performed to assess for threads or string location. If unsuccessful, ultrasound or plain abdominal radiographic imaging may be used to locate the IUD. Once IUD migration has been confirmed, cross-sectional imaging such as CT scans or magnetic resonance imaging (MRI) is suggested to rule out adjacent organ involvement before considering surgical removal.4 If colonic involvement is suspected, colonoscopy can be used to confirm the diagnosis before operative removal.4
Although management of a migrated IUD in an asymptomatic patient is controversial, there appears to be a consensus that all extrauterine devices should be removed unless the patient’s surgical risk is excessive.1,5,9 Retrieval of an IUD can be performed by laparotomy or laparoscopy.10,11
To avoid these complications and interventions, IUDs should be inserted by an appropriately trained professional, after proper patient selection. These devices should be monitored by periodic examinations, either by medical professionals or by well-informed patients. This can be done by either checking for the threads or string in the cervical opening or by ultrasound imaging to confirm the location of the IUD.
Conclusion
Although many patients with uterine perforation and IUD migration present with symptoms, approximately 30% are asymptomatic.3 If a patient has a lost IUD and the threads or string is not visible during pelvic examination, appropriate work-up, including transvaginal or transabdominal ultrasound or radiographs, should be obtained to confirm the position of the IUD. If IUD migration is suspected, cross-sectional imaging, such as CT scans or MRI, is recommended to rule out adjacent organ involvement before considering surgical removal.4
Even though only 15% of migrated IUDs lead to complications in the adjacent visceral organs,6 surgical removal of the IUD is advised regardless of the presence of symptoms or identified complications. Importantly, to prevent the delayed diagnosis and morbidity of IUD migration, patients with IUDs should be educated about the possibility of migration and the importance of regular self-examination for missing threads or string.