Uterine blood flow and perfusion in mares with uterine cysts: effect of the size of the cystic area and age.

Transrectal color and power Doppler ultrasonography was used to study uterine blood flow and perfusion in mares with and without uterine cysts. Vascular perfusion of the uterus and blood flow velocities, vascular perfusion, diameter, circumference, and area of a cross section of the mesometrial attachment were evaluated. To study the effect of internal cysts, two matched groups (cystic and control, n=21 mares/group) were used. Uterine vascular perfusion in mares with cysts was less (P<0.0001) in the cystic than the noncystic region and less (P<0.0009) than that for controls. Mares with cysts had lower (P<0.04) pulsatility index (PI) and greater end diastolic velocity (EDV; P<0.03) and time-averaged maximum velocity (TAMV; P<0.05) of the mesometrial vessels than the controls. To study the effect of the size of internal uterine cystic area, paired mares were arranged in four groups (n=8-11/group): small uterine cystic area (< or =275 mm(2)) versus controls and large uterine cystic area (>410 mm(2)) versus controls. A small uterine cystic area did not affect uterine hemodynamics. Mares with large uterine cystic area had lower PI (P<0.05) and greater peak systolic velocity (P< or =0.05), EDV (P<0.009), and TAMV (P<0.005). To study the effect of age, old versus young mares without cysts were compared (n=11/group). Old mares had greater EDV (P<0.02) and TAMV (P<0.01) than young mares. Results demonstrated, for the first time in any species, reduced uterine vascular perfusion in mares with uterine cysts and a positive association between size of the cystic area and disturbed uterine hemodynamics.