Human menopausal gonadotropin during in vitro maturation of human oocytes retrieved from small follicles enhances in vitro fertilization and cleavage rates.

OBJECTIVES

To compare the IVF rates of oocytes retrieved from small follicles (< 2 mL in volume) with those of oocytes retrieved from large follicles and to test the effect of adding gonadotropins to the IVF medium on the fertilization rates of oocytes from small follicles.

DESIGN

Oocytes were retrieved with endovaginal ultrasound (US) guidance from patients undergoing infertility treatment in our IVF program. Oocytes were grouped according to the volume of the originating follicle and subjected to our routine procedure for IVF. HMG was added to the IVF medium for some of the oocytes from small follicles.

SETTING

Toronto Fertility and Sterility Institute is affiliated with the University of Western Ontario and University of Toronto and is equipped for RIA, endovaginal US monitoring and oocyte retrieval, and for processing and culturing gametes and embryos.

PATIENTS

Infertile patients admitted to our IVF program.

INTERVENTIONS

Patients underwent ovarian stimulation with hMG before oocyte retrieval. No other interventions were introduced to the processing and culturing the gametes and embryos except the addition of hMG to the medium of some of the small follicle-originated oocytes with the informed consent from the patients.

MAIN OUTCOME MEASURES

Rates of fertilization, cleavage of the fertilized embryos before replacement, and meiotic status of some of the oocytes from small follicles.

RESULTS

Most of the oocytes from small follicles did not complete the first meiotic division; they had low rates of fertilization and cleavage compared with oocytes from large follicles, and these rates were improved by the addition of hMG to the IVF medium.

CONCLUSIONS

Oocytes from small follicles are probably less mature and require a more physiological environment to achieve normal rates of fertilization and cleavage.