In the late stage of pregnancy, the uterine wall of Xiaowei Han sheep begins to thicken, and the volume of the uterus gradually increases significantly. Regardless of the exploration method used, the uterus is easier to find. However, in order to provide a basis for confirming pregnancy through ultrasound examination before the uterine body has significantly increased in the early stages of pregnancy.

If the dark area of the gestational sac and early fetal reflex are seen in the uterine region, it can be determined that early pregnancy can be achieved in just a few seconds by a skilled operator. On the 23rd day of pregnancy in the small tailed Han sheep, a typical sheep with a gestational sac can be diagnosed with pregnancy by using B-ultrasound imaging, and the fetal reflex inside the gestational sac can be observed. The circular dark area in front and below the liquid dark area of the bladder is the early gestational sac

In the image, the hypoechoic dark area in the middle is fetal water, and the echoic light cluster inside the gestational sac is reflected by the fetal body. On the 24th day of pregnancy, the gestational sac slightly enlarged, but the difference in imaging between the two days was not significant. As the fetus develops, the required nutrients increase, the gestational sac enlarges, the fetal water increases, and the uterine wall further thickens. On the 28th and 32nd day of pregnancy, the gestational sac of the sheep can be seen to have significantly enlarged gestational sac and increased fetal reflex, presenting a recognizable fetal shape. From the imaging until the 40th day of pregnancy, it can be seen that the proportion of water in the gestational sac is relatively high, which can be used as a reference when determining gestational age.

Someone used sheep ultrasound technology to diagnose pregnancy in 280 female sheep after 76-146 days of mating, with an accuracy rate of 100%; Someone used B-ultrasound technology to diagnose pregnancy in 87 ewes after 15-120 days of mating. It was found that the accuracy of B-ultrasound testing was high for sheep over 30 days after mating, and the diagnostic rate could reach 100% after 40-60 days of mating. Some people also use sheep ultrasound to detect early pregnancy in 110 pregnant ewes, and the accuracy of detection can reach 100% after 26 days of mating.