Of the estimated 50,000 women worldwide who have been sterilized hysteroscopically with the Essure procedure (Conceptus, Inc., Mountain View, Calif.) since 1997, at least 64 have unintentionally become pregnant, according to the authors of a summary of the procedure's use to date.  

The procedure involves placing hysteroscopically microinserts containing polyethylene terephthalate fibers into the fallopian tubes. The fibers promote a benign, localized tissue growth that typically occludes the tubes within 3 months. 

As of December 2005, 64 unintended pregnancies were reported to the manufacturer of the device. While most of the pregnancies occurred in patients who did not receive proper follow-up after the procedure, some occurred because of misread hysterosalpingograms, undetected preprocedure pregnancies, and failure to follow product-labeling guidelines.  

Levy B, Levie MD, Childers ME. A summary of reported pregnancies after hysteroscopic sterilization. 

Of the estimated 50,000 women worldwide who have been sterilized hysteroscopically with the Essure procedure (Conceptus, Inc., Mountain View, Calif.) since 1997, at least 64 have unintentionally become pregnant, according to the authors of a summary of the procedure's use to date.