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The objective of this study was to define several estimates of the success rate of in-vitro fertilization and embryo transfer treatment in relation to treatment outcome. The data were collected in a retrospective study of 591 patients treated during 3 years in one Belgian university hospital. Several models used for evaluating the treatment of infertility were fitted to the data (logistic model, binomial model, double binomial model, exponential model, the Speirs model. The number of oocytes retrieved and the proportion of fertilized oocytes at the first attempt can be used as prognostic factors. According to these factors, the success rate after five attempts varies from 28 to 88%.

Mature spermatozoa contain a number of proteases that are supposed to contribute to their fertilizing ability. The present study was directed at plasminogen activator (PA), a protease that belongs to the group of serine proteases and converts the zymogen plasminogen to the active broad-spectrum protease plasmin. To investigate the possible role of PA in the fertilization process, we have measured sperm-bound PA activity in 63 patients included in an in-vitro fertilization (IVF) programme and assessed their relationship to standard semen parameters and the rate of fertilization. PA activity was correlated significantly with the sperm count, as well as with sperm motility and morphology. Using logistic regression analysis, specific PA (pmol pNA 10(-6) cells min-2) was found to significantly influence the probability of fertilization. Other significantly predictive factors were motility and the percentage of spermatozoa with normal morphology. The sperm concentration (10(6) cells ml-1) did not significantly affect the outcome of IVF. We suggest that sperm-bound PA is involved in the fertilization process and may represent a potential indicator of sperm fertilizing capacity.

Benefits of the short-term utilization of a gonadotropin-releasing hormone (GnRH) agonist (Buserelin, Hoechst, AG, Frankfurt am Mein, FRG) for induction of ovulation in an in vitro fertilization program (IVF) program were assessed. Eighteen patients underwent consecutively an induction of ovulation by clomiphene citrate (CC) and human menopausal gonadotropin (hMG), then by hMG alone, and finally by Buserelin and hMG. The switchover from CC and hMG to hMG alone significantly increased the number of aspirated follicles and the oocyte recovery rate. The addition of Buserelin prevented the outcome of spontaneous luteinizing hormone (LH) surges. It reduced the preovulatory luteinization and increased the number of recovered oocytes as well as the number of embryos available for transfer. A 33% clinical pregnancy rate per ovum pick-up was achieved with the Buserelin-hMG treatment.