The first ultrasound can be done in 6 weeks of pregnancy, but only in a few cases, such as heavy vaginal bleeding, vaginal inflammation, etc. Pregnant women can choose the appropriate examination according to their own situation and medical advice. 1. Compared to abdominal ultrasound, vaginal ultrasound can observe the uterine cavity more clearly and the gestational sac can be observed earlier. Abdominal ultrasound is more convenient and easier for pregnant women to accept psychologically. Pregnant women can choose the appropriate examination according to their own needs and doctor’s advice. 2. No vaginal ultrasound: In 6 weeks of pregnancy, vaginal ultrasound cannot be performed in very few cases, such as in case of heavy vaginal bleeding or vaginal inflammation, at this time, if vaginal ultrasound is performed, it may lead to intrauterine infection, and it is recommended to choose abdominal ultrasound. If a pregnant woman is 6 weeks pregnant and has no special needs, it is generally recommended to take abdominal ultrasound examination, which is simple and convenient and can meet the requirements of maternity examination. However, if there are special circumstances, such as pregnant women with scarred uterus, vaginal ultrasound may be required without too much worry about affecting fetal development, infection, miscarriage, etc. The risk of these conditions occurring is very low.