FRACTURED ZONA OOCYTES IN INVITRO FERTILIZATION CYCLES STIMULATED WITH GONADOTROPIN-RELEASING-HORMONE ANALOG AND HUMAN MENOPAUSAL GONADOTROPIN

In order to assess the possible influence of gonadotrophin-releasing hormone analogue and human menopausal gonadotrophin on the occurrence of fractured zona oocytes (FZOs) in in-vitro fertilization (IVF) treatment cycles, we analysed 267 consecutive cycles in 199 patients. In 87 cycles, at least one fractured zona oocyte was recovered, and in 180 cycles only intact zona oocytes (IZOs) were recovered. FZOs represented 5.8% of all oocytes retrieved and 14.8% when only cycles with FZOs were considered. Serum oestradiol concentrations were significantly higher at day -3 and day -2 (P < 0.02) in cycles yielding at least one fractured zona oocyte compared to IZO cycles (day 0 = retrieval day), and there was a higher incidence of G terminal pattern of oestradiol curve (P < 0.01) in cycles with FZOs. The mean numbers of all oocytes retrieved and of mature oocytes were significantly higher in FZO than in IZO cycles (P < 0.001). The fertilization rate of mature oocytes was significantly reduced (P < 0.05) in cycles with one or more oocytes with fractured zonae. There was no significant difference in the number of embryos transferred, pregnancy and abortion rates in both groups. We conclude that although the occurrence of fractured zona oocytes is a frequent event, it does not affect the overall results of our IVF programme. Zona pellucida fragility may be the result of over-maturation of some oocytes.