Pharmacokinetics of exogenous gonadotropin and ovarian response in in vitro fertilization

Objective: To assess the diffusion of gonadotropin into the follicular fluid (FF) and its relation to the results achieved in a human IVF-ET program. Design: Retrospective pharmacokinetic study. Setting: Fukuoka University Hospital, Japan. Patient(s): Eighty-seven infertile patients underwent 137 cycles of IVF-ET. Intervention(s): Serum and FF were collected at the time of oocyte recovery. The hCG ratio (between follicular hCG and serum hCG concentrations, measured by time-resolved fluoroimmunoassay) was evaluated as an index of the diffusion of exogenous gonadotropin. Main Outcome Measure(s): Relation between hCG ratio and the results and outcome of the IVF-ET program. Result(s): The hCG ratio decreased with the total dosage of hMG and increased with the serum E-2 level, the number of oocytes recovered, and the number of oocytes fertilized. Patients with a poor response showed a low hCG ratio, which was associated with a complete lack of fertilization. The mean hCG ratio in the pregnant cycles was significantly higher than that in the nonpregnant cycles. An hCG ratio >0.46 was seen in all pregnant cycles. Conclusion(s): The diffusion of exogenous gonadotropin into the FF may be an important predictor of IVF outcome. (C) 1999 by American Society for Reproductive Medicine.