Changes in perifollicular vascularity after administration of human chorionic gonadotropin measured by quantitative three-dimensional power Doppler ultrasound. 
To determine the perifollicular vascular network and blood flow changes of the dominant preovulatory follicle using quantitative three-dimensional (3D) power Doppler analysis.  A total of 21 cycles were studied in spontaneously ovulating women who underwent folliculometry and 3D power Doppler angiography of perifollicular blood flow of the dominant preovulatory follicle on the day of human chorionic gonadotropin (hCG) administration and 24 h after it.  At 24 h after the administration of hCG, increases were found in the area inside the biggest follicular circumference (8.48 +/- 1.73 cm(2) vs. 9.30 +/- 1.64 cm(2)), in the percentage of vessel volume inside the perifollicular capsule (3.58 +/- 3.65% vs. 7.76 +/- 10.13%) and in total perifollicular blood volume (931.33 +/- 1084.60 vs. 3486.00 +/- 7272.34).  Moreover, the rearrangement in blood volume distribution resulted in equalization of the contribution of each feeding vessel to total perifollicular blood flow.  A more uniform vascular network resulting in decreased dominance of a single feeding vessel in total inflow was found (50.50 +/- 28.18% vs. 29.05 +/- 14.14%).  After the administration of hCG there was a visible increase in perifollicular capillary network volume, relative volume of blood, and balancing of blood inflow of each feeding vessel of the perifollicular circulation.