Peripheral blood concentrations of inhibin B are elevated during gonadotrophin stimulation in patients who later develop ovarian OHSS and inhibin A concentrations are elevated after OHSS onset.

Ovarian hyperstimulation syndrome (OHSS) is a serious side-effect of controlled ovarian stimulation. Inhibin A and inhibin B, as putative predictors of OHSS development in the same stimulation cycle, were evaluated. A cohort of 428 in-vitro fertilization (IVF) patients was followed. Fifteen patients with severe OHSS were compared with matched (age, follicle number) controls. Serum samples were obtained at five time points from the start of ovarian stimulation until >/= 3 days post-embryo transfer and analysed with specific enzyme-linked immunosorbent assays. Inhibin A in the OHSS group showed a continuous increase with a significant elevation 3 days prior to oocyte aspiration (ASP-3) and onwards. Maximal concentrations were detected at embryo transfer and the concentrations remained high at >/= 3 days post-embryo transfer. Inhibin A concentrations in the control group showed a transient elevation (significant increase at ASP and embryo transfer). Inhibin A in the OHSS group was significantly higher than in controls only at the time point where OHSS had developed (>/= 3 days post-embryo transfer), and declined during OHSS treatment. Overall, there was a positive correlation between the number of follicles and inhibin A concentrations at ASP-3 until embryo transfer in the control group but not in the OHSS group. The concentrations of inhibin B in both groups increased from the start of ovarian stimulation, with peak values at ASP-3, and then a decline. Inhibin B was significantly higher in OHSS patients at ASP-3 and at ASP. Inhibin B at ASP-3 was correlated with the total number of follicles in both the OHSS group and the control group.