LH surge induction by GnRH agonist at the time of ovulation.

Eight women were treated for 1 cycle at the time of ovulation with GnRH agonist (3 injections of 0.2 mg buserelin s.c. at 12-hour intervals) to obtain follicular rupture. Clomiphene citrate was administered to 1 patient and pure FSH to 2 patients, whilst in the case of a woman with hypothalamic amenorrhea a pulsatile GnRH regimen was used. Four patients had an untreated follicular phase. When the maximal follicular diameter was 20-22 mm all treatments were withheld and GnRH-A was administered. Plasma LH, FSH, progesterone and estradiol were determined 24 hours before, at the time of and 12, 24 and 48 hours after the 1st injection of buserelin. Ovulation was detected in all cycles. LH levels increased dramatically from baseline levels of 14.4 +/- 4.1 to 155 +/- 48 IU/l 12 hours after the beginning of treatment, then returned to preovulatory values 48 hours later (13.0 +/- 3.9 IU/l). The duration of the luteal phase was 13.2 days and normal mid-luteal progesterone plasma levels were detected (39.8 +/- 9.3 nmol/l). These data suggest that the GnRH agonist can be successfully used at the time of ovulation to induce an endogenous ovulatory LH peak and that it can be used in conjunction with different medical treatments to induce follicular maturation.