Can we estimate the minimum number of oocytes retrieved based on follicle diameter on trigger day? Α cohort study

Is it possible to estimate the minimum number of oocytes retrieved based on the follicular diameter present on the day of triggering of final oocyte maturation in women undergoing ovarian stimulation for IVF?

This observational cohort study included data from 330 patients undergoing 429 IVF cycles from September 2020 to May 2024. The primary outcome measure was oocyte retrieval rate, which was calculated for each follicular diameter between 11 and 24 mm, recorded on the day of triggering, by dividing the number of oocytes retrieved by the number of follicles of the specific follicular diameter or larger. To estimate the minimum number of oocytes retrieved, the smallest follicular diameter on the day of triggering in which the lower 95% confidence interval (95% CI) of the corresponding oocyte retrieval rate reached or exceeded 100% was determined.

At oocyte retrieval, the median number of oocytes retrieved was 5.0 (95% CI 5.0-5.3) and the median number of metaphase II oocytes was 4.0 (95% CI 3.0-4.0). The lower 95% CI of the oocyte retrieval rate reached or exceeded 100% for the first time when the follicular diameter on the day of triggering used for its calculation was 16 mm (median oocyte retrieval rate 103.3%, 95% CI 101.3-105.3%). The corresponding diameter for the prediction of the mature oocytes retrieved was 18 mm (median oocyte retrieval rate 133.3%, 95% CI 112.5-154.2%).

These data and the methodology used could be useful in the context of effective patient counselling, clinical decision making and laboratory preparation.