Threatened miscarriage refers to a small amount of vaginal bleeding occurring before 28 weeks of pregnancy. Usually, the amount of bleeding does not exceed that of a normal menstrual period, and the blood may be dark red or appear as bloody vaginal discharge. The color of the bleeding is not significant. No pregnancy tissue is expelled initially, and this may be followed by episodic lower abdominal pain or back pain, although these symptoms may not occur. During a gynecological examination, the cervix is closed, the membranes are intact, and the size of the uterus corresponds to the gestational age. After rest and treatment, the symptoms may disappear, and the pregnancy can continue. If the amount of vaginal bleeding increases or lower abdominal pain intensifies, accompanied by the expulsion of pregnancy tissue, it progresses to inevitable miscarriage. Inevitable miscarriage refers to a miscarriage that cannot be avoided. Based on the symptoms of a threatened miscarriage, the amount of vaginal bleeding increases, and episodic lower abdominal pain intensifies, possibly accompanied by vaginal fluid discharge. During a gynecological examination for inevitable miscarriage, the cervix is dilated, and embryonic tissue or the amniotic sac can be seen obstructing the cervical opening.