Characteristics of patients with and without gonadotropin surges during follicular recruitment in an in vitro fertilization/embryo transfer program.

Fifteen ovulatory patients undergoing ovarian stimulation with clomiphene citrate-human menopausal gonadotropin-human chorionic gonadotropin (hCG) for in vitro fertilization were studied. All 15 attained peak estradiol (E2) levels of greater than 600 pg/ml. Eight patients had an endogenous luteinizing hormone (LH) surge before the administration of hCG. The characteristics of these "surge" patients were compared with those of the remaining seven "nonsurge" patients. There was no significant difference in the peak morning E2 achieved before hCG or the endogenous LH surge, nor in the peak absolute increase in E2 over a 24-hour period in these two groups. The surge group had significantly higher E2 levels per follicle greater than or equal to 15 mm, measured by ultrasound on the morning of the day of administration of hCG or the LH surge (P less than or equal to 0.005). In addition, nonsurge patients had a greater number of follicles greater than or equal to 15 mm, compared with surge patients (P less than or equal to 0.05). It is hypothesized that greater quantities of nonsteroidal hormones, such as inhibin, produced by a greater number of preovulatory follicles in nonsurge patients, may block the pituitary response to hypothalamic gonadotropin-releasing hormone in the face of high and rising E2 levels.