Ultrasound can be done at 5 weeks of pregnancy. During pregnancy, you need to go to the hospital regularly for various checkups, among which ultrasound is very important. Through ultrasound, you can observe the development of the fetus at different stages and determine whether there is any developmental abnormality in the fetus. When an ultrasound is performed at five weeks of pregnancy, usually only a round or oval-shaped gestational sac can be seen in the uterine cavity. It is only when the ultrasound is performed at around 7 weeks of pregnancy that the primordial heart tube pulsation and embryonic buds may be seen in the uterine cavity, which indicates that the fetus is intrauterine and can develop normally. If you experience any discomfort during pregnancy, such as vaginal bleeding or lower abdominal cramps, you should go to the hospital for an examination.