Evidence from a salvaged treatment cycle supports an aetiology for the empty follicle syndrome that is related to terminal follicular developmental events.

Oocyte retrieval in a stimulated in-vitro fertilization treatment cycle was unsuccessful when inadvertently carried out 12 h after the administration of human chorionic gonadotrophin (HCG) injection. Repeat follicular aspiration at 36 h post-HCG injection recovered 20 oocytes, out of which 16 metaphase-II eggs were subjected to intracytoplasmic sperm injection and eight became fertilized. Uterine transfer of three cleaving embryos resulted in a singleton pregnancy which went to term and a healthy female infant was delivered. Our experience shows that in addition to issues of HCG bioavailability to the developing follicles, the temporal relationship between HCG administration (or the luteinizing hormone surge) and follicular aspiration is also an important consideration in the determination of the aetiology of the empty follicle syndrome.