The symptoms of threatened miscarriage primarily include a small amount of vaginal bleeding and mild lower abdominal pain or sacral pain. Threatened miscarriage refers to the occurrence of a small amount of vaginal bleeding before 28 weeks of pregnancy, often dark red in color, with no pregnancy tissue expelled. This may be accompanied by intermittent lower abdominal pain or back pain, or it may occur without any pain symptoms. During a gynecological examination, the cervix is closed, the membranes are intact, and the uterine size matches the gestational age. After rest and treatment, the symptoms may disappear and the pregnancy can continue. If the amount of vaginal bleeding increases or the lower abdominal pain worsens, accompanied by dilation of the cervix and expulsion or shedding of pregnancy tissue, it can progress to an inevitable miscarriage, which then requires prompt and active management to terminate the pregnancy.