Adverse events due to suspected nickel hypersensitivity in patients with essure micro-inserts

To review reported adverse events associated with suspected nickel hypersensitivity and subsequent clinical outcomes in patients with Essure implants and to evaluate the correlation of nickel allergy-related adverse events with positive results of nickel patch testing.

Case series (Canadian Task Force classification II-3).

Reports of suspected nickel hypersensitivity reported from 2001 through July 21, 2010, were collected from de-identified data obtained from the MAUDE (Manufacturer and User Facility Device Experience) database and reports to the manufacturer directly from treating physicians, and published results for the 650 patients in the Phase II and Pivotal trials. Clinical outcomes and symptom resolution, when available, were obtained from de-identified information provided by the treating physicians to the manufacturer. Patients were not directly contacted for the study, and patient files were not reviewed. Patch testing was performed at the discretion of the treating physicians. Results were reported as positive or negative, without mention of the method or brand of patch testing used.

Even considering the possibility of underreporting by several orders of magnitude, the reported incidence of adverse events suspected to be related to nickel hypersensitivity in patients with Essure micro-inserts is extremely small (0.01%). The incidence of confirmed nickel reactions is even smaller. This very low incidence of clinical reactions is consistent with data from other nickel-containing implantable devices and is reassuring, raising the question of whether nickel reactions are clinically relevant in the use of nitinol-containing micro-inserts for hysteroscopic sterilization.