Number and Size of Antral Follicles as Predictive Factors in In Vitro Fertilization and Embryo Transfer

Purpose: The purpose of the study was to evaluate whethernumber and size of antral follicles can predict the outcomeof in vitro fertilization—embryo transfer.Methods: A total of 113 patients were prospectively includedinto this study. After 19 days of down-regulation, numberand size of follicles were determined by using recent three-dimensionaltransvaginal ultrasound technology. Beforeapplication of gonadotropin, all follicles had been definedas antral follicles. According to size, antral follicles werecategorized into four different groups: group I includedantral follicles < 5 mm, group II follicles 5–10 mm; groupIII 11–20 mm; and group IV >20 mm. Pregnant and non-pregnantpatients were compared in terms of their numberof antral follicles of group I–IV. These four groups were thencompared regarding implantation rate, number of retrievedoocytes, endometrium thickness, and age.Results: Pregnant patients showed an significant highernumber of follicles with the size between 5 and 10 mm (P=0.04). A significant correlation was found between numberof retrieved oocytes and antral follicle size of 5–10 mm(P= 0.0001). Antral follicles with a diameter between 5and 10 mm decreased significantly with age (P = 0.008).In groups III and IV, a significant correlation was foundbetween antral follicle size (P = 0.016) and serum estradiollevel after gonadotropin-releasing hormone-agonist down-regulation (P = 0.011).Conclusions: We demonstrated that patients with a highernumber of follicles between 5 and 10 mm showed a significantlyhigher pregnancy rate, whereas patients with a dominantnumber of antral follicles > 11 mm have a highercancellation rate due to ovarian low response.