A vaginal ultrasound can be done at 5 weeks and 3 days of pregnancy, but it is not recommended for those who have vaginal bleeding. Vaginal ultrasound refers to vaginal ultrasound, and compared to normal transabdominal ultrasound, there is no need to fill the bladder, the examination time is shorter, and the images are relatively clearer. At 5 weeks and 3 days of pregnancy, the pregnancy sac cannot be seen in the uterine cavity by transabdominal ultrasound, but when vaginal ultrasound is used, it is possible to see the presence of the pregnancy sac in the uterine cavity, which is of some diagnostic value in ruling out ectopic pregnancy. However, it is important to pay attention to the vaginal ultrasound examination, and it is not recommended if there is vaginal bleeding, so as not to increase the chance of infection. In conclusion, whether a woman who is 5 weeks and 3 days pregnant can undergo a vaginal ultrasound examination needs to be determined by the doctor after an interview based on the woman’s specific situation.