THE OVARIAN HYPERSTIMULATION SYNDROME IN IN-VITRO FERTILIZATION - A BELGIAN MULTICENTRIC STUDY .1. CLINICAL AND BIOLOGICAL FEATURES

The multicentric study regroups 128 cases of the ovarian hyperstimulat ion syndrome (OHSS) in in-vitro fertilization (IVF) and 256 selected c ontrols. Values of serum oestradiol obtained from different laboratori es were found to be normally distributed after logarithmic transformat ion. Comparative study of clinical and biological characteristics indi cates that among OHSS patients (i) mean age was lower; (ii) tubal indi cations for IVF were less frequent; (iii) polycystic ovary-like condit ions (i.e. hyperandrogenism, anovulation, luteinizing hormone/follicle stimulating hormone ratio >2) were more frequent. OHSS patients displ ayed ovarian hypersensitivity reflected by higher oestradiol peak conc entrations in response to lower dosage of human menopausal gonadotroph in and by a steeper slope of oestradiol increment during stimulation. In these patients, the collection of greater numbers of fertilizable o ocytes allowed replacement of more embryos with a good vitality score. Ongoing pregnancy rate was found to be higher among the OHSS patients . The following complications were recorded among OHSS cases: abdomina l fluid at echographic examination or clinical ascites (86.7 and 71.1% , respectively); pleural and pericardial effusion (21 and 3%, respecti vely); haemoconcentration (71.1%); electrolytic disorders (6.2%). Alth ough significantly different between groups, clinical and biological p arameters under study showed considerable overlap of their distributio ns in control and OHSS cases. Therefore, these data must be submitted to discriminant analysis in order to derive a formula predictive of th e risk of OHSS.