Four cases of heterotopia of an intrauterine device embedded in the bladder muscular layer causing cystolithiasis: case report and review of the literature

Family planning is a basic national policy in China. An intrauterine device (IUD) is an important method of achieving family planning owing to its high safety, low cost, and convenient use. The indwelling birth control ring has no obvious adverse effects on the sexual life of women after the operation, and the process is reversible. This ring can be removed for women who want to have children again. There are approximately 100 million women with IUDs worldwide, with approximately 80 million in China. This finding accounts for approximately 40% of women of childbearing age in China. Although an IUD is safe, the invasive operation inevitably leads to complications, such as pelvic infection, abnormal menstruation, and damage to adjacent organs. Among them, ectopic bladder stone formation is a rare complication, but several related cases have been reported. We report four cases of heterotopia of an IUD and cystolithiasis, with diagnosis based on the medical history, clinical manifestations, imaging, and cystoscopic findings. The four patients with ectopic IUDs were treated with cystoscopy combined with laparoscopy (or hysteroscopy). We describe the process of diagnosis and treatment of our patients, and the related literature on an ectopic IUD is reviewed.