The aim of this study was to evaluate the accuracy of the ECF test for detecting the pregnancy status and embryonic mortality and to compare the reliability of ECF test from among ultrasonography and serum progesterone level. In this study, two groups were designed: the study group (n = 15) and control group (n = 9). All cows were observed for estrus activity four times daily. Cows in the study group were inseminated. After insemination, at the 7, 20, 30 and 45th days ECF test and ultrasonographic examination were applied to check the pregnancy status. Cows in the control group were not inseminated and examination procedure was performed like in the study group. Twenty days after insemination, pregnant positive cows that had been determined by ultrasonography were designated the study group. Twenty days after insemination, ECF test were applied and progesterone levels were determined in the serum samples obtained from pregnant positive cows. Fifteen cows in the study group were checked 20 days after insemination and determined pregnant. Their pregnancy status was confirmed 20 days after insemination by using ultrasonography. In the 30 th and 45th days ultrasonography was repeated, after which 13 cows were determined pregnant. In the serum of these two cows progesterone levels fell under 2 ng/ml. However, in the 20th day these cows' progesterone levels was higher than 2 ng/ml, in two cows embryonic death occurred. In cows which were determined as pregnant by ultrasonography at the 20th day, the ECF test was applied at the 7th day and 10 cows from this group had a positive reaction (66.7%). Test specificity, PPV and NPV results were 44.4%, 66.7% and 44.4% respectively; at the 20th day the ECF test was positive for 9 cows (60%), specificity, PPV and NPV results were 33.3%, 60.0% and 33.3%; at the 30th day, the ECF test was positive for 12 cows (92.3%), test specificity, PPV and NPV results were 45.5%, 66.7% and 83.3%; at the 45th day, 10 cows (76.9%), test specificity, PPV and NPV results were 54.5%, 66.7% and 66.7% respectively. Between the study groups, the ECF test accuracy at the 7th and 20th days were found lower than at the other days. The test's accuracy was determined the highest at the 30th day (70.8%), and the lowest at the 20th day (50%). The results show that ECF test is an unreliable method for pregnancy diagnosis and for determining embryonic death in dairy cows and these data indicate that the current ECF test cannot accurately identify the nonpregnant cows
