Development and influence of an endogenous serum luteinizing hormone surge after ovulation induction in stimulated cycles.

The aim of this study was to investigate whether the endogenous serum luteinizing hormone (LH) discharge in stimulated cycles--either simultaneously with or shortly after exogenous human chorionic gonadotropin (hCG) administration--is influenced by serum steroid hormones and follicle stimulating hormone (FSH). We also tested whether the LH discharge affects intrafollicular hormone metabolism and oocyte fertilization. In a group of 46 women with tubal pathology who were undergoing in vitro fertilization (IVF), follicular fluids were collected during oocyte retrieval. In addition blood samples were drawn daily, starting at cycle day 7 until the day of oocyte retrieval. LH, FSH, estradiol, progesterone, testosterone and prolactin were determined in all samples of serum and follicular fluid. Oocyte maturation was classified according to the morphology of the oocyte corona-cumulus complex. Of the 46 women studied, 15 showed no LH surge (group A) and 31 developed an endogenous LH surge (group B). Serum samples showed no significant differences between the two groups in follicular phase estradiol, progesterone, testosterone and prolactin. Only levels of serum FSH showed a significant difference between groups A and B (p < 0.0005). In follicular fluid samples LH (p < 0.05) and FSH levels (p < 0.005) were significantly different. Fertilization rate and cleavage rate, however, did not differ significantly. The late endogenous LH surge occurring simultaneously with or shortly after hCG application for ovulation induction did not affect intrafollicular steroid metabolism, oocyte maturation, fertilization rate or cleavage rate.