Vaginal ultrasound after pregnancy has no effect on the child; on the contrary, it can assist in clinical diagnosis much earlier and better. A transvaginal ultrasound (vaginal ultrasound) is an ultrasound performed with a long strip of probe deep inside the vagina. Some pregnant women believe that vaginal bleeding will occur after the ultrasound and that this will increase the risk of miscarriage or preterm delivery. The small amount of vaginal bleeding is caused by irritation of the cervix during the exam and is not intrauterine bleeding. Unlike X-rays and CT examinations, there is no radiation or electromagnetic radiation, and it is virtually harmless to the body. There have been no definitive studies on the adverse effects of diagnostic ultrasound on the embryo or fetus. It is the same as abdominal ultrasound, except that the probe is placed in a different position and the doctor changes the condom on the probe for each patient examined, without increasing the risk of infection. For the following cases, we should perform vaginal ultrasound more: if you have had a cesarean section and are pregnant again at 6-7 weeks, you should do a negative ultrasound to clarify the distance between the gestational sac and the uterine scar, to exclude scar pregnancy, suspected cervical insufficiency, you should monitor the change in cervical length continuously at 2-week intervals starting at 14-16 weeks of pregnancy, suspected placental abnormalities, it is difficult to see the relationship between the placenta and the endocervix with abdominal ultrasound in late pregnancy, negative ultrasound can well The abdominal ultrasound in late pregnancy is difficult to see the relationship between the placenta and the endocervix, and the negative ultrasound can clarify the dangerous conditions such as placenta praevia, umbilical cord previa, and previa.