Placenta with blood sinus may disappear. Placental blood sinus is a pregnant woman in the ultrasound examination, some localized blood flow of the placenta is more rich in the region, in the ultrasound imaging will see a dark area, called placental blood sinus. This placental blood sinus is also mostly a physiological change that cannot be artificially altered, and may increase, decrease or even disappear on its own in the course of fetal development. This kind of placental blood sinus generally has no adverse effect on the pregnant woman and the fetus, if the pregnant woman and the fetus have no other abnormalities, just simply found a placental blood sinus, generally do not need to worry too much, and do not need special treatment. If the pregnant woman has vaginal bleeding, abdominal pain, etc., ultrasound found that the placenta has a dark area, need to be vigilant for placental abruption, placental hemorrhage, etc., and should be timely medical treatment.