Delayed occurrence of an LH surge after HCG administration during ovarian stimulation with gonadotrophins: effect of LHRH treatment.

Previous studies have shown the appearance of a spontaneous luteinizing hormone (LH) surge after human chorionic gonadotrophin (HCG) administration in human menopausal gonadotrophin (HMG)/HCG-stimulated menstrual cycles. In this report we investigated the effect of leuprolide acetate, a long-acting luteinizing hormone releasing hormone (LHRH) agonist, on the occurrence of these post-HCG rises in serum LH. Two groups of patients were included. Group 1: 10 patients receiving HCG as a part of an HMG/HCG protocol for induction of follicular development in an IVF/GIFT program and Group II: 10 patients treated as Group I, but receiving the LHRH agonist leuprolide acetate to inhibit gonadotrophin secretion prior to and during ovarian stimulation. In Group I, none of the patients showed a surge prior to HCG administration. However, an LH surge following HCG treatment was apparent in four patients (40%). Pregnant patients (2/10) had low mean levels (less than or equal to 2.5 mIU/ml LH) in the follicular phase and showed no LH surge after HCG. In Group II, baseline levels of serum LH were reduced significantly (mean, 1.4 +/- 0.1 mIU/ml; P less than 0.001) compared to Group I. No patient showed an LH surge either before or after HCG administration and the occurrence of pregnancy was higher (6/9 transfers) than in Group I. In spite of the differences in pregnancy rates, the combined therapy versus HMG therapy showed no significant difference in number of oocytes collected or serum oestradiol levels. This suggests that high levels of serum LH, whether prior to or after HCG administration, may have a detrimental effect on the establishment of pregnancy despite adequate follicular growth.(ABSTRACT TRUNCATED AT 250 WORDS)