Transvaginal three-dimensional ultrasound: Accuracy of follicular volume measurements

Objective: 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 (D-1 x D-2 x D-3) 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 mt for 3-D measurements and +3.47 to -2.42 mt 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.