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 h ormone analogue and human menopausal gonadotrophin on the occurrence o f fractured zona oocytes (FZOs) in in-vitro fertilization (IVF) treatm ent cycles, we analysed 267 consecutive cycles in 199 patients. In 87 cycles, at least one fractured zona oocyte was recovered, and in 180 c ycles only intact zona oocytes (IZOs) were recovered. FZOs represented 5.8% of all oocytes retrieved and 14.8% when only cycles with FZOs we re considered. Serum oestradiol concentrations were significantly high er at day -3 and day -2 (P < 0.02) in cycles yielding at least one fra ctured zona oocyte compared to IZO cycles (day 0 = retrieval day), and there was a higher incidence of G terminal pattern of oestradiol curv e (P < 0.01) in cycles with FZOs. The mean numbers of all oocytes retr ieved and of mature oocytes were significantly higher in FZO than in I ZO cycles (P < 0.001). The fertilization rate of mature oocytes was si gnificantly 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 f requent event, it does not affect the overall results of our IVF progr amme. Zona pellucida fragility may be the result of over-maturation of some oocytes.