Objective: To evaluate the relationship between 2 dimensional sonographic measurement of ovarian follicles and their actual volume.
Design: Prospective clinical study.
Setting: The in vitro fertilization (IVF) program of a University based, tertiary care hospital.
Patients and interventions: Sonographic categorization by shape, and measurement of 96 individual ovarian follicles immediately prior to aspiration for IVF. Each follicle was aspirated under direct ultrasound guidance and the volume recorded. The 96 follicles were visualized in a total of 14 patients from whom 2 to 27 oocytes were obtained.
Main outcome measure: Total volume of each follicle.
Results: Round and polygonal follicles exhibited a highly significant relationship between sonographically measured mean diameter and total follicle volume. The volume of follicles that were categorized as ellipsoid was not predicted by measurement of the longest diameter, shortest diameter or mean diameter.
Conclusion: The mean diameter of round and polygonal follicles accurately predicts total follicular volume. However, clinical decisions in ovulation induction should be modified when the follicle shape is predominantly ellipsoid because the traditionally held belief that the sonographic measurement of the follicular diameter correlates with the follicular volume does not apply in those circumstances.