Switching from cetrorelix to dydrogesterone in an IVF cycle - a new strategy for unexpected freeze-all cycles.

Preventing a luteinizing hormone (LH) surge is a major concern in controlled ovarian stimulation (COS). Several strategies have been developed over the years, including protocols with Gonadotrophin Releasing Hormone agonists and antagonists. More recently Progestin Primmed Ovarian Stimulation (PPOS) has shown to be equally effective in pituitary suppression, with comparable clinical and laboratorial outcomes.