There is no need to hold urine for ultrasound at 10 weeks of gestation, because at the end of 5 weeks of gestation the chorionic vasculature is formed, at 8 weeks of gestation the placental circulation is established, maternal serum penetrates through the fetal membrane into the dialysis fluid of the amniotic cavity, forming amniotic fluid, about 5-10ml can be seen by ultrasound. At 10 weeks of gestation, the amount of amniotic fluid can reach 30ml, and the fetus can move freely in the amniotic fluid. With the help of the liquid dark area of the amniotic fluid, the ultrasound can clearly detect the fetus and placenta, and at this time, pregnant women do not need to hold urine for the fetal ultrasound. In early pregnancy, it is necessary to hold urine to understand the situation of the pregnancy sac, because the bladder can push open the intestinal canal after the bladder is filled with urine, and the distended bladder forms a liquid dark area, and the liquid dark area forms a sharp contrast with the surrounding tissues, so it can clearly understand the situation of the uterus and adnexa behind the bladder.