Implanon® : difficultés d'insertion et de retrait, échecs contraceptifs

Abstract

Analysis of the results of a national pharmacovigilance study on Implanon, a contraceptive implant containing 68 mg of etonogestrel. This survey concerns cases of pregnancies (contraception failures), of migrations and of insertion or removal problems with Implanon reported to French Regional Drug Pharmacovigilance Centres and to Organon SA between May 2001 and September 2002. In France, 39 unintended pregnancies were reported over 17 months. The pregnancies were in 77% of cases (N = 30) due to an insertion technique error (implant not found when pregnancy has been diagnosed). For 3 patients (7,6%), pregnancy was due to a failure of etonogestrel contraceptive effect, explained twice by its association with an enzymatic inductor drug. For 4 patients (10%), pregnancy was due to an untimely insertion (insertion after day 5 of menstrual cycle or woman already pregnant). For two patients, no information was available. The incidence of reported pregnancies in France is estimated at 0.359 / 10(3) implants [0.246-0.482], in accordance with a typical Pearl Index of 0.06 [0.04-0.08]. Twenty-eight suspected migrations (N = 11), problems or failures in removal of the implant (N = 11) and insertion difficulties (N = 6) were notified, corresponding to an incidence of 0.257/10(3) implants [0.162-0.363]. Occurrence of pregnancy is possible with Implanon, due to errors in the insertion technique (device not really inserted) or to a non-respect of the SPC recommendations (drug-drug interaction or untimely insertion). Insertion problems can lead to localisation problems (implant not visible by X-ray) then needing further tests and even harmful practice (removal under general anaesthesia). That is why a real and strict training is highly recommended to physicians.