Ovarian hyperstimulation syndrome and assisted reproductive technologies: Why some and not others?

Abstract

Background: α2-Macroglobulin (α2M) is a multifactorial binding protein, found in follicular fluid, that is a naturally occurring inhibitor of vascular endothelial growth factor (VEGF). The aim of this study was to determine if there is a relationship between serum VEGF levels, α2M levels and the development of OHSS in hyperstimulated subjects undergoing IVF (those with 15 or more oocytes). Methods: Venous blood was collected at the time of oocyte retrieval from subjects who yielded 15 or more oocytes. Serum samples were analysed for VEGF and α2M concentrations. Results: There was no statistically significant difference in serum VEGF levels at the time of oocyte retrieval between hyperstimulated subjects who did and did not subsequently develop OHSS [3.95 (3.3-4.4) versus 3.85 (3.3-4.5); P = 0.79]. By contrast, the serum level of α2M was statistically significantly higher in the group of subjects who did not develop OHSS [2.27 (1.91-2.58) versus 1.67 (1.45-1.73)]. Conclusions: These results suggest that elevated α2M levels are associated with a decreased risk of developing OHSS. α2M may act by 'removing and inactivating' VEGF, with higher levels providing increased protection against the syndrome. α2M measurements may help to differentiate those for whom it is safe to proceed with embryo transfer from those for whom it is not, because of the risk of OHSS.