TREATMENT VARIABLES IN RELATION TO OOCYTE MATURATION - LESSONS FROM ACLINICAL MICROMANIPULATION-ASSISTED IN-VITRO FERTILIZATION PROGRAM

Objective: In an effort to understand the mechanism underlying the imp roved pregnancy rate observed in IVF cycles when gonadotropin-releasin g hormone analogues (GnRH-a) are applied, we investigated a possible r elationship between treatment variables and oocyte nuclear maturity. D esign: Nuclear maturity was retrospectively assessed in cumulus-free, denuded oocytes, obtained from women undergoing micromanipulation-assi sted IVF treatment following controlled ovarian hyperstimulation with GnRH-a and menotropins.Setting: The setting was the infertility and IV F unit of a tertiary academic medical center. Participants: Two hundre d twenty-one patients underwent 435 treatment cycles. Main Outcome Mea sure: This was the proportion of germinal vesicle-intact immature (GVI I) oocytes. Results: One hundred fifty-four of the 3520 oocytes studie d (4.4%) were in the GVII stage. These oocytes were found in 66 of the treatment cycles (15.2%) and in 54 of the patients (24.4%). Cycles in which GVII oocytes were detected did not differ from those in which a ll the aspirated oocytes were mature in the following respects: patien t age, type and duration of infertility, controlled ovarian hyperstimu lation protocol and time of ovum pickup. However the GVII group was ch aracterized by a significantly higher peak estradiol level, as well as a higher number of mature follicles visualized sonographically (diame ter >14 mm) and oocytes retrieved. Conclusions: Comparing the present findings with previously published data, it appears that the inclusion of GnRH-a in the stimulation regimen is associated with a lower propo rtion of immature oocytes. A higher occurrence of oocyte-nuclear immat urity is apparently associated with a significantly better ovarian res ponse to stimulation. The high incidence of immature oocytes observed in patients with normospermic partners and low fertilization rates in previous cycles may suggest that the fertilization failure in some of these cases is due to oocyte, rather than sperm, dysfunction.