A negative ultrasound during pregnancy usually does not cause bleeding, which is mostly caused by poor embryonic development or pre-miscarriage. Ultrasound during pregnancy can more accurately identify intrauterine pregnancy, and can also rule out the possibility of ectopic pregnancy and gravida and other pathologic pregnancies. A negative ultrasound can be chosen because it is more intuitive and clearer than an abdominal ultrasound and can detect intrauterine pregnancy earlier than an abdominal ultrasound. A negative ultrasound does not usually cause bleeding. When vaginal bleeding occurs in early pregnancy, it is mostly due to causes such as preeclampsia or embryonic dysplasia, etc. It can be combined with blood HCG (human chorionic gonadotropin) levels, progesterone and other tests to assist in the diagnosis, and it is important to follow the doctor’s instructions for proper rest, and to actively give progesterone, urotropin, and other medications to preserve the fetus.