Assessment of follicular maturity by follicular diameter and fluid volume in a program of in vitro fertilization and embryo transfer.

We compared the assessment of follicular maturity by follicular diameter or follicular fluid (FF) volume and the subsequent fertilization and cleavage of the oocytes in 36 patients who had ovarian stimulation performed for in vitro fertilization and embryo transfer (IVF-ET). All patients received clomiphene citrate and human menopausal gonadotropin. The daily growth of follicles was assessed ultrasonically for 6 consecutive days before oocyte collection. The follicular diameter was found to be well correlated with the volume of follicular fluid. There were no significant differences among the dominant, second, and third follicles in the rates of oocyte recovery, maturation, fertilization, or cleavage. The rates of oocyte maturation and fertilization in FF volumes of 5.1 to 7.0 ml were significantly higher than in volumes of 1.1 to 5.0 ml, but the cleavage rates were similar. A smaller percentage of embryos developed to the four-cell stage when the oocytes were recovered from follicles with volumes of 1.1 to 3.0 ml. These observations suggest that follicular volume is a good parameter for judging the maturity of oocytes. It is also suggested that, although the oocytes of small follicles can be fertilized and cleaved, oocytes from larger follicles may have a better developmental capacity.