If the blood is bright red after the ultrasound, it is usually divided into the following cases: 1. In early pregnancy, the patient’s gestational sac is poorly developed, there are signs of miscarriage, some gestational sacs are deformed, the fetal buds have stopped developing and blood has accumulated in the uterine cavity, which is slowly discharged after the ultrasound. 2. In early pregnancy, some patients have no obvious abnormalities in the gestational sacs and fetal buds, but endocrine abnormalities, such as progesterone, can also be signs of miscarriage. 3. In the presence of ectopic pregnancy, the gestational sac does not settle in the middle of the uterine cavity, but in the cervical, fallopian tube or ovarian area, and vaginal bleeding may also occur. Some patients who have had uterine surgery or cesarean delivery will have scars on the uterine wall and will also bleed if the gestational sac lays in the scars.4. When an ultrasound is done in the middle of pregnancy, some patients will have intermittent bleeding if the placenta praevia is present. Having an ultrasound is usually done in early pregnancy and it is very helpful in identifying intrauterine and ectopic pregnancies, observing the development of the fetal buds and the test itself does not cause harm to the gestational sac or the fetus.