Threatened miscarriage primarily refers to the occurrence of a small amount of vaginal bleeding before 28 weeks of pregnancy, often dark red or blood-stained discharge, with no pregnancy tissue expelled. The amount of bleeding generally does not exceed that of a menstrual period and may be accompanied by intermittent pain in the lower abdomen or the sacral area. During a gynecological examination, the cervix is not dilated, the membranes are intact, and the size of the uterus corresponds to the gestational age. After rest or treatment, the symptoms may alleviate, allowing the pregnancy to continue. If vaginal bleeding increases and lower abdominal pain intensifies, and all or part of the pregnancy tissue is expelled through the vagina, a miscarriage that cannot be avoided is considered. In this case, it is necessary to terminate the pregnancy promptly to avoid endangering the pregnant woman's life due to excessive bleeding.