Quantifying the changes in endometrial vascularity throughout the normal menstrual cycle with three-dimensional power Doppler angiography

BACKGROUND: We used three-dimensional power Doppler angiography (3D-PDA) to examine the periodic changes in endometrial and subendometrial vascularity during the normal menstrual cycle in 27 women without obvious menstrual dysfunction or subfertility. METHODS: 3D-PDA was performed on alternate days from day 3 of the cycle until ovulation and then every 4 days until menses. Virtual organ computer-aided analysis and shell-imaging were used to define and to quantify the power Doppler signal within the endometrial and subendometrial regions producing indices of their relative vascularity. RESULTS: Both the endometrial and subendometrial vascularization index (VI) and vascularization flow index (VFI) increased during the proliferative phase, peaking similar to3 days prior to ovulation (P < 0.001) before decreasing to a nadir 5 days post-ovulation (P < 0.001). Thereafter, both vascular indices gradually increased during the transition from early to mid-secretory phase. The flow index (FI) showed a similar pattern but with a longer nadir post-ovulation. Smoking was associated with a significantly lower VI and VFI. The FI was significantly lower in women aged greater than or equal to31 years and significantly higher in parous patients. CONCLUSIONS: Endometrial vascularity, as assessed by 3D-PDA, varies significantly during the menstrual cycle and is characterized by a pre-ovulatory peak and post-ovulatory nadir during the peri-implantation window.