Assessment of changes in volume and vascularity of the ovaries during the normal menstrual cycle using three-dimensional power Doppler ultrasound

BACKGROUND: Our aim was to describe changes in the volume and vascularization of both ovaries, the dominant follicle and the corpus luteum during the normal menstrual cycle using three-dimensional (3D) power Doppler ultrasound. METHODS: Fourteen healthy volunteers underwent serial transvaginal 3D ultrasound examinations of both ovaries on cycle day 2, 3 or 4, then daily from cycle day 9 until follicular rupture and 1, 2, 5, 7 and 12 days after follicular rupture. The volume and vascular indices of the ovaries, the dominant follicle and the corpus luteum were calculated off-line using virtual organ computer-aided analysis (VOCAL) software. RESULTS: The volume of the dominant ovary increased during the follicular phase, decreased after follicular rupture and then increased again during the luteal phase. Vascular indices in the dominant ovary and the dominant follicle/corpus luteum increased during the follicular phase, the vascular flow index (VFI) in the dominant follicle being on average (median) 1.7 times higher on the day before ovulation than 4 days before ovulation (P=0.003). The vascular indices continued to rise after follicular rupture so that VFI in the corpus luteum was on average (median) 3.1 times higher 7 days after ovulation than in the follicle on the day before ovulation (P=0.0002). The volume and vascular indices in the non-dominant ovary manifested no unequivocal changes during the menstrual cycle. CONCLUSIONS: Substantial changes occur in volume and vascularization of the dominant ovary during the normal menstrual cycle. 3D power Doppler ultrasound may become a useful tool for assessing pathological changes in the ovaries, for example, in subfertile patients.