EN
Transrectal colour Doppler ultrasonography is a useful non-invasive technique used for the assessment of blood flow through the reproductive organ during various cycle phases, pregnancy, and postpartum period. It also provides additional information on physiological and pathological processes in the ovaries and the uterus, which may contribute to the development of new methods for the treatment of reproductive disorders in cattle. The purpose of this work was to present the use of Doppler ultrasonography, which consists in the colour imaging of blood flow through vessels, during the reproduction of cattle. During the oestrus cycle in cows, colour Doppler ultrasonography and the so-called Power Doppler are excellent tools for the assessment of ovarian follicles during the oestrus cycle and of changes during the first 12 weeks after calving. It has also been used to examine the effects of superovulation by measuring the uterine blood flow and its relationship with the steroid hormone level, reaction of ovaries, and the number of embryos obtained in cows. Hormonal stimulation is related to a significant increase in blood flow velocity (BFV) and a reduction in the pulsation index (PI) in uterine arteries, concurrent with the development of numerous follicles and corpora lutea. Colour Doppler techniques can offer useful information for the assessment of corpus luteum (CL) function. Since proper angiogenesis plays an important role in correct CL functioning, research on blood flow volume may provide valuable information on CL physiology and physiopathology. Doppler ultrasonography is also an excellent method for the differentiation of ovarian cysts. The blood flow field in the cyst wall was found to be positively correlated with the progesterone level in blood. Colour Doppler ultrasonography has also been used to investigate the relationship between vascular blood flows inside the uterine horns during pregnancy and the location of the embryo, as well as for the assessment of its development rate on the basis of the endometrial vascularisation index. It has also been found that CL vascularisation increases in the first three weeks of pregnancy, and the assessment of CL parameters between the 5th and the 10th day after insemination could be a valuable method for pregnancy diagnosis as well as a marker for pregnancy loss. The transrectal colour Doppler ultrasonography method considerably accelerates and improves the detection of fertility disorders, which results in direct economic benefits of production.