APPLICATION OF COLOUR DOPPLER ULTRASONOGRAPHY FOR OVARIAN BLOOD FLOW EXAMINATION IN COWS – A REVIEW

Abstract

The purpose of this review article is to summarize the data concerning the application of colour Doppler ultrasonography for examination of the ovaries in cows. The main indication for performing a Doppler ultrasound of the ovaries is to determine the changes in the ovarian blood flow during the follicular and luteal phases of the estrus cycle. The available literature shows that measurement of follicular blood flow is suitable for identifying the future dominant follicle at an early stage of development and for predicting the viability of the follicles after deviation. Additionally, examining the number of follicles with detectable blood flow was applied to predict the superovulatory response. In this regard, measurement of follicular blood flow by color Doppler ultrasonography has used to detect follicular development and to predict the correct time of ovulation. Colour Doppler ultrasonography is used to differentiate follicular and luteal cysts, which has crucial importance in choosing appropriate treatment. The better sensitivity of this diagnostic method (92.3%) than B-mode ultrasonography (61.5%) in determination of the follicular luteinization degree, shows that blood flow intensity is more accurate indicator for detection of active luteal tissue compared to wall thickness measurement. During the entire estrus cycle, there is higher positive correlation between luteal blood flow (LBF) and the progesterone level than between corpus luteum cross-sectional area (corpus luteum size) and progesterone (P4). Because of this fact, LBF increase can be used to establish early luteal function. On the base of close relationship between LBF and P4 values during the early and late luteal phases, it is accepted that LBF determination may distinguish developing (functional) and regressing (nonfunctional) corpora lutea with the same size. In conclusion, the current literature analysis indicates that transrectal colour Doppler ultrasonography is useful technique for examination of the reproductive organs blood flow and opens a new window for ovarian function investigation in cows.