Follicular fluid-specific distribution of vascular endothelial growth factor isoforms and sFlt-1 in patients undergoing IVF and their correlation with treatment outcomes

Objective: To investigate the distribution of vascular endothelial growth factor (VEGF) isoforms and soluble form of VEGF receptor 1 (sFlt-1) in the follicular fluid (FF) of in vitro fertilization (IVF) patients in relationship to age, body mass index (BMI), diagnosis of polycystic ovary syndrome (PCOS), and their correlation with IVF outcomes. Design: Prospective study. Main Outcome Measures: VEGF₁₂₁ and VEGF₁₆₅ isoforms were detected using Western blotting and pixel density analysis. The concentration of sFlt-1 was determined by enzyme-linked immunosorbent assay (ELISA). In vitro fertilization outcomes measured included number of oocytes retrieved, fertilization rate, and clinical pregnancy. Statistical analysis used the Kruskal-Wallis and Mann-Whitney U test where appropriate. Results: There was a statistically significant association between higher VEGF₁₆₅ levels and the diagnosis of PCOS, BMI ≥ 30, and age ≥40 years. In vitro fertilization cycles resulting in pregnancy were linked to statistically lower VEGF₁₆₅ levels in the FF. No statistically significant trend was identified in levels of VEGF₁₂₁ or sFlt-1 relative to patient characteristics or IVF outcomes. Conclusion: Our results suggest that elevated VEGF₁₆₅ levels are associated with less favorable patient characteristics and clinical IVF outcomes.