Objectives: To evaluate the accuracy of three-dimensional (3-D) ultrasound (US) follicular volume measurements.
Design: Prospective clinical study.
Setting: A tertiary referral center for assisted reproduction.
Patients: Twenty-five patients undergoing ovarian stimulation for IVF-ET using the long protocol of GnRH agonist.
Intervention: Transvaginal two-dimensional (2-D) and 3-D ovarian scan performed immediately before US-directed follicle aspiration.
Main outcome measures: The volume of follicular fluid aspirated was compared with the corresponding volume of the follicle measured by 3-D US and with the conventional 2-D US volume measurement calculated using the formula pi/6 (D1 x D2 x D3). Limits of agreement and 95% confidence intervals were calculated and systematic bias between the methods was analyzed.
Results: The limits of agreement between the volume of follicular aspirate and follicular volume determined by US were +0.96 to -0.43 mL for 3-D measurements and +3.47 to -2.42 mL for 2-D measurements.
Conclusions: The true volume of ovarian follicles, within the clinically useful range for IVF-ET cycles, is measured more accurately by a 3-D US system than by 2-D US techniques.