The unclear cavity line in women mainly indicates the possibility of endometrial damage or endometrial adhesions, which may lead to abdominal pain and discomfort, decreased menstrual flow, amenorrhea, secondary infertility or habitual miscarriage. Because when a woman has endometrial damage or adhesions, the basal layer of the endometrium is damaged, and even if a woman’s ovaries are functioning normally and her estrogen levels are normal, the patient’s endometrium is unable to proliferate, secrete and exfoliate bleeding normally, so when the patient has an ultrasound, the endometrium is very thin, the cavity line is not clear, and the menstrual flow is very low. In women with thin endometrium, if it does not reach more than 0.7cm, the fertilized egg cannot be properly fertilized, which can easily lead to biochemical pregnancy due to failure of fertilization. Also, if the patient has adhesions in the endometrium, it can lead to narrow cavity of the uterus. If the patient is pregnant, the fetus will increase in size in the middle and late stages of pregnancy, but the pressure in the narrow cavity will increase, which may lead to premature rupture of the fetal membranes, placenta abruptio, stillbirth and other adverse consequences.