The relationship between follicle diameter, fertilization rate, and microscopic embryo quality.

The diameter of preovulatory ovarian follicles was measured at the time of transvaginal US-guided oocyte retrieval, and the oocytes were subsequently examined to assess fertilization rates and the quality of developing embryos. With follicles divided into three groups of increasing diameter, there were no significant differences in the fertilization rates of oocytes recovered from follicles of different size. Embryo quality improved with increasing follicle size, although the differences were not highly significant. Our results demonstrate that an acceptable laboratory outcome can be achieved with oocytes retrieved from smaller sized follicles.