Objective: To explain the unexpected low response to GnRH antagonist protocol in reproductive women with normal baseline hormone profiles.
Design: Retrospective study.
Setting: University hospital.
Patient(s): Twenty-five women undergoing their first IVF cycle.
Intervention(s): Follicular fluid (FF) from large follicles (>15 mm) was obtained during oocyte retrieval from unexpected low responders (n = 13, group A) and 12 age-matched normal responders (n = 12, group B).
Main outcome measure(s): The FF markers known to reflect follicle environment (insulin-like growth factor [IGF] II, IGF-binding protein 4, müllerian-inhibiting substance, pregnancy-associated plasma protein A, soluble Fas, and vascular endothelial growth factor [VEGF]) were analyzed by ELISA.
Result(s): The baseline characteristics (age, day 3 serum LH, FSH, E(2), duration and dose of r-FSH, GnRH antagonist) were not different between the two groups. The number of large follicles, oocytes retrieved, and serum E(2) levels on the day of hCG injection were significantly higher in group B. Whereas the other follicular markers did not differ between the two groups, VEGF was significantly higher in group A. In addition, the VEGF concentration showed an inverse correlation with the total number of oocytes retrieved.
Conclusion(s): The unexpected low response in women with normal basal hormone profiles, during GnRH antagonist protocol, was associated with altered follicular VEGF expression.