Objective: To investigate if the presence of an abnormally large follicle during controlled ovarian hyperstimulation (COH) under pituitary suppression has any effect on the outcome of the cycle.
Design: Prospective, observational.
Setting: The reproductive endocrinology unit of a university hospital.
Patients: One hundred fifty patients undergoing COH for assisted reproductive techniques during a 6-month period (August 1990 to January 1991).
Interventions: Transvaginal follicular aspiration and IVF-uterine ET.
Results: A total of 19 cycles had abnormally large follicles identified on day 8 of the stimulation cycle after normal baseline ultrasound. Gonadotropins were continued and hCG injection was indicated when two or more follicles of the main cohort achieved a diameter of 20 to 22 mm. Twenty preovulatory oocytes were retrieved from 22 large follicles. Two were transferred for GIFT and 18 were inseminated in vitro, resulting in a 72.0% fertilization rate. The mean number of oocytes retrieved per patient was 10.9, 71.4% of which were mature with a fertilization rate of 67.7%. All these figures were comparable with the results obtained in the 131 patients of the control group undergoing IVF. No evidence of premature luteinization was observed in the study group, based on plasma P levels (x 0.83 ng/mL [conversion factor to SI unit, 3.180], range 0.31 to 1.40 ng/mL). The clinical pregnancy rate for the group with abnormally large follicles did not differ from the control group (27.8% versus 28.2%, respectively).
Conclusions: The presence of an abnormally large follicle during COH under pituitary suppression does not affect the outcome of the cycle. Moreover, under these conditions, continuous gonadotropin stimulation of a follicle to diameters considerably larger than the standard ones does not have a detrimental effect on the oocyte contained in it, suggesting that oocyte aging is an independent process from follicular growth once LH surge is prevented.