Follicular fluid VEGF levels directly correlate with perifollicular blood flow in normoresponder patients undergoing IVF

BACKGROUND: It has become increasingly clear that the follicular microenvironment of the maturing human oocyte is a determining factor for the implantation potential of an embryo deriving from that oocyte. Indeed the quality and maturity of an oocyte are influenced by the level of intrafollicular oxygen content which, in turn, is proportional to the degree of follicular vascularity. The aim of the study was to establish whether there is a relationship between follicular fluid VEGF concentrations, perifollicular vascularity and reproductive outcome in normal responders under the age of 35 undergoing IVF. MATERIALS AND METHODS: Sixty-one consecutive patients, all at their first IVF cycle, were included in the study. All patients had primary infertility due to male factor or tubal factor. At oocyte retrieval, the perifollicular vascularity of two follicles per ovary was estimated qualitatively through power Doppler blood flow, for a total of two hundred forty-four follicles. The follicular fluid from the identified follicles was centrifuged and stored until VEGF assay. The maturity and fertilization rate of the corresponding oocytes as well as embryo quality and pregnancy rate were recorded. RESULTS: In our study, we found VEGF levels to be significantly correlated with grade of perifollicular vascularity. Oocytes obtained from follicles with the higher grade of vascularization also showed a higher rate of fertilization, embryos, a better quality and higher pregnancy rates were obtained in women with highly vascularized follicles. Perifollicular blood flow doppler indices seem to predict oocyte viability and quality. Moreover, VEGF may play a potential role in the development of the perifollicular capillary network. DISCUSSION: The ability of a given follicle to express VEGF and develop an adequate vascular network may be inter-related in patients under the age of 35. An adequate blood supply may be fundamental important in the regulation of intrafollicular oxygen levels and the determination of oocyte quality.