A common question among health care professionals is how to manage nonvisible strings in users of intrauterine contraceptives (IUCs) at repeat follow-up visits. This study assessed the position of the IUCs in women who consulted repeatedly with nonvisible IUC strings. The medical records of the clinic were reviewed to identify new acceptors and switchers who had an IUC inserted between 1990 and 2009. All women were identified whose IUC string could not be visualized at the external os of the cervix by the health care professional at any given follow-up visit, even after attempting a standard maneuver of sweeping the strings from the cervical canal using a cervical brush or trying to visualize the strings in the cervical canal using colposcopy. Data were also retrieved on the use of ultrasonography and/or pelvic X-ray to assess IUC position, as well as data from any subsequent visits at which the IUC strings were nonvisible. The medical charts of 14,935 patients using an IUC were reviewed, and 750 women (5.0%) presenting for the first time with missing IUC strings at any follow-up visit were identified. Ultrasound scans showed the IUC to be in situ in 735 cases (98.0%), while 9 women (1.2%) had expelled the device and, in 5 cases (0.7%), the device was found in the pelvis following uterine perforation. IUC strings were missing on a second occasion in 297 cases. The device was found to be in situ in 295 cases (99.3%) and had been expelled in 2 (0.7%). At subsequent consultations, (between 1 and 18 years after the first consultation), strings were missing in 113, 55, 19 and 5 cases. In 111 (98.2%), 54 (98.2%), 18 (94.7%) and 5 (100%) of these cases, respectively, the IUC was found to be in situ, while in the remaining cases, the device had been expelled. Missing IUC strings are an uncommon finding, and ultrasonography confirmed that the device was in situ in the majority of these cases. For women with persistent missing IUC strings after one ultrasound scan that has verified appropriate intrauterine position, given the 2.4% likelihood that expulsion may have occurred at the time of subsequent visits, repeating the ultrasound (if available) should be considered for at least one (and possibly two) additional women's visit.86354-8