Z-Scores for Assessing Ovarian Reserve in Young Patients Undergoing Fertility Preservation

We wanted to assess ovarian reserve based on small ovarian samples in patients aged up to 25 years old that require fertility preservation through ovarian tissue cryopreservation. Using a modified formula that estimates the total number of follicles in ovarian samples and the model for normal ovarian volume, we established a reference dataset for follicle densities in women age zero to 25 years old. Assessing the normality of follicle density is difficult because of, one, the natural decline of ovarian reserve with increasing age.

And two, the heterogeneous distribution of follicles. Comparison to reference values is also challenging because they're not standardized to age and biopsy size, so we're trying to bridge this gap. Our protocol describes the strategy for assessing the normality of follicle density based on small ovarian samples.

We directly quantify these follicles using histology and compare the results to age-normalized standard references via z-scores. With this tool, meta-analysis become possible because we can compare data from multiple studies. It is important to know if the ovarian reserve is low.

We focus on identifying patients with reduced ovarian reserve and suggest a cutoff value for that. This is of great value for physicians in counseling their patients, for autotransplantation of their cryopreserved ovarian tissue, as well as for further treatment after fertility preservation.