Sexual Assault

Emergency Contraception: Mechanism of Action

Providing emergency contraception (EC) is a standard part of the sexual assault medical-forensic exam. However, I find that a lot of clinicians have a difficult time explaining how EC works so that patients can make a well-informed choice about whether they want it. So I was pleased to get an email yesterday announcing the availability of a new fact sheet on EC (PDF), outlining what the science tells us about mechanism of action. It should be a great resource to provide team members and our collaborating colleagues in the emergency departments who are often responsible for having similar conversations with patients.

“The International Consortium for Emergency Contraception (ICEC) and the International Federation of Gynecology and Obstetrics (FIGO) present a revised version of their fact sheet on the mechanism of action of levonorgestrel-alone emergency contraceptive pills (LNG ECPs). To develop this fact sheet, FIGO and ICEC worked with an international team of prominent doctors and experts in human reproduction to review the latest published studies on the mechanism of action of LNG ECPs. A careful review of the most recent evidence shows that the main mechanism of action of this emergency contraceptive method is to prevent or delay ovulation. The evidence is strong that this method does not interfere with implantation of a fertilized egg in the endometrium; evidence about a possible effect on sperm function is inconclusive.”

The fact sheet is available in Spanish, German and French (PDF), as well. The email I received also said a Portuguese version is forthcoming.