Clinically endometrial blood flow is usually categorized into three grades, where grade III is the best blood flow status and is normal. Type I endometrial flow indicates that the blood vessels have crossed the outer hypoechoic zone of the endometrium and have not yet reached the outer hyperechoic edge of the endometrium, type II indicates that the blood vessels have crossed the outer hyperechoic edge of the endometrium and have not yet entered the hyperechoic zone of the endometrium, and type III indicates that the blood vessels have entered the hyperechoic zone of the endometrium. The endometrial blood flow status is usually one of the criteria for determining the health of the endometrium. If the endometrial blood flow is good, it will help the pregnancy and the live birth. If the endometrial blood flow is found to be poor, it may be a sign of preterm miscarriage. Poor endometrial blood flow may be caused by the endometrium not growing properly. If the patient has poor endometrial blood flow, he/she should go to the hospital in time for early treatment.