Comparison of two methods to measure the area of ultrasonography images of corpus luteum in sheep

Ultrasonography (US) is a helpful tool for studying follicular and luteal dynamics, ovulation, and embryo development. However, there is currently no gold standard reference technique for estimating the size of the corpus luteum (CL). The aim of this study was to compare the results from measuring ewes’ CL size based on its’ diameter or its’ surface with the aid of image software. The study involved 19 ewes, recording the images of 50 CLs at different stages of development, and therefore, calculating its’ size by both procedures. The results showed that measuring the CL diameter to calculate its’ area is a rapid and reliable technique that can effectively substitute the measurement of the surface, which requires precision and time. The study concluded that measuring the two main axes of the CL is a valid method for effectively estimating its size.