Number and size of antral follicles as predictive factors in vitro fertilization and embryo transfer

Abstract

Purpose: The purpose of the study was to evaluate whether number and size of antral follicles can predict the outcome of in vitro fertilization-embryo transfer.

Methods: A total of 113 patients were prospectively included into this study. After 19 days of down-regulation, number and size of follicles were determined by using recent three-dimensional transvaginal ultrasound technology. Before application of gonadotropin, all follicles had been defined as antral follicles. According to size, antral follicles were categorized into four different groups: group I included antral follicles < 5 mm, group II follicles 5-10 mm; group III 11-20 mm; and group IV > 20 mm. Pregnant and non-pregnant patients were compared in terms of their number of antral follicles of group I-IV. These four groups were then compared regarding implantation rate, number of retrieved oocytes, endometrium thickness, and age.

Results: Pregnant patients showed an significant higher number of follicles with the size between 5 and 10 mm (P = 0.04). A significant correlation was found between number of retrieved oocytes and antral follicle size of 5-10 mm (P = 0.0001). Antral follicles with a diameter between 5 and 10 mm decreased significantly with age (P = 0.008). In group III and IV, a significant correlation was found between antral follicle size (P = 0.016) and serum estradiol level after gonadotropin-releasing hormone-agonist down-regulation (P = 0.011).

Conclusions: We demonstrated that patients with a higher number of follicles between 5 and 10 mm showed a significantly higher pregnancy rate, whereas patients with a dominant number of antral follicles > 11 mm have a higher cancellation rate due to ovarian low response.