The effects of 'coasting' on follicular fluid concentrations of vascular endothelial growth factor in women at risk of developing ovarian hyperstimulation syndrome

BACKGROUND: The aim of this study was to assess the effect of withholding gonadotrophins (coasting) during controlled ovarian stimulation (COS) on individual follicle concentrations of follicular fluid vascular endothelial growth factor (VEGF) in women at high risk of developing ovarian hyperstimulation syndrome (OHSS). METHODS: Twenty-two women who had been coasted and 26 optimally responding women (control group) undergoing COS for IVF were studied. At the time of oocyte retrieval, the follicular fluid from four to six individual follicles of different sizes was collected for VEGF analysis. RESULTS: A total of 118 follicles was analysed in the coasted group and 137 in the control group. A negative correlation was observed between the follicle size and VEGF concentration (r = -0.18, P = 0.03) in the control group, which was not seen in the coasted group. Similarly, the correlation between oestradiol (E(2)) and VEGF (r = 0.4, P < 0.0001) observed in the control group was not apparent in the coasted group. Significantly lower concentrations of VEGF were seen in the follicular fluid of the coasted patients. CONCLUSIONS: It is clear that there are differences in follicular fluid VEGF concentrations between the two groups. It is possible that coasting alters the capacity of the granulosa cells to produce VEGF and/or their response to hCG and in this way acts to reduce the severity and incidence of severe OHSS.