Uterine blood flow during various stages of pregnancy in dairy buffaloes using transrectal Doppler ultrasonography.

Reference data to assess function and perfusion of uteroplacental tissues by assessment of uterine blood flow parameters is not available in buffaloes. The objective of the present study was to assess and quantify blood flow parameters at various stages of gestation. A total of 54 Murrah buffaloes, six animals at every month of gestation, from two months to ten months, were subjected to transrectal Doppler ultrasonography to assess uterine blood flow in both the middle uterine arteries. Resistance and pulsatility indices, velocity and volume of blood flow, diameter of the artery and notch signal were measured for different waveforms. The resistance index value was positively correlated with pulsatility index (r=0.94, P<0.05) but negatively correlated with all other parameters for both arteries, ipsilateral and contralateral to the fetus. With a significant advancement of pregnancy, there was reduction in resistance index with a significant increase in velocity, volume of blood flow and diameter in both arteries. There was a significant increase in the volume and velocity of blood flow (P<0.05) during the last trimester with increased growth demands of the fetus. The notch signal disappeared by 20-24 weeks. Thus, transrectal Doppler ultrasongraphy proved to be a useful non-invasive method to assess the uterine blood flow during pregnancy in buffaloes. This could be a valuable tool to ascertain hemodynamic changes in complicated pregnancy (e.g. abnormalities in uterine blood flow/placenta/fetus) and its extent of deviation from normal.