Study Objectives: To examine the imaging modality used in cases of Essure failures and determine the cause of the unintended pregnancies (noncompliance to follow-up recommendations, misinterpretation of the imaging test, or device failure). Design: Retrospective, single-center interventional cohort (Canadian Task Force classification II-2). Setting: Tertiary level hospital. Patients: Women who have had Essure placement and subsequent pregnancy. Interventions: Coding data from the Regina General Hospital was examined for any pregnancy occurring after an Essure procedure. The hospital charts were then reviewed for data collection. A separate imaging database established over the same time frame was then reviewed to determine the imaging modality used in each case (transvaginal ultrasound [TVU], hysterosalpingogram [HSG], or none). Results of the imaging study were reviewed and the cause of the failure determined. Measurements and Main Results: Twenty-four pregnancies in 25 women were identified after Essure procedures from January 1, 2003 to March 31, 2013. There were 4 in vitro fertilization pregnancies and 4 pregnancies where the woman had been instructed not to rely on the devices because of incomplete placement noted at time of the procedure. Therefore, 17 unintended pregnancies occurred of a total 2080 procedures performed. Examination of the imaging studies revealed that 11 were due to patient noncompliance (either early cessation of backup contraception or failure to go for confirmatory imaging), 5 due to misinterpretation of the imaging tests (3 HSG, 2 TVU), and 1 device failure. This reveals a cumulative failure rate of 6 of 2080 or .29% over 10 years with only .04% (1/2080) being device related. Conclusion: Essure sterilization is an effective means of permanent contraception with a device failure rate of only .04%. Most unintended pregnancies after the Essure procedure result from a failure to comply with follow-up recommendations, and strategies to improve compliance should be emphasized. (C) 2016 AAGL. All rights reserved.