Premature luteinization of follicles during ovarian stimulation for in-vitro fertilization.

The structure and growth of developing follicles was monitored using vaginal ultrasound scanning in an outpatient programme of in-vitro fertilization (IVF) and embryo transfer (ET). Patients received either human menopausal gonadotrophin (HMG) alone or clomiphene citrate (CC) + HMG for controlled ovarian stimulation. Ultrasound data were compared with pre-ovulatory oestradiol (E2), luteinizing hormone (LH) and progesterone (P) levels. Hormonal parameters and results were classified according to the main indications of IVF-ET treatment. Twenty-one of the 271 patients in the study showed ultrasonic evidence of premature luteinization (PL) of follicles, thickening of the follicular wall and the appearance of irregular echogenic structures in the follicle. PL was preceded in eight cases by an indisputable LH surge and subsequent P elevation. In the remaining 13 cases PL occurred either due to an abortive LH surge not exceeding by 3-fold the baseline values or as a result of HMG administration. Special attention was paid to the P pattern prior to and after human chorionic gonadotrophin (HCG) administration. PL cycles demonstrated significantly (P less than 0.05) higher P levels before HCG administration and at the time of oocyte retrieval as well. Because implantation was not achieved in these cases, the cancellation of PL cycles is recommended. Vaginal ultrasound scanning seems to be helpful in the evaluation of minor changes in the follicular structure, correlating frequently with hormonal findings.