It is possible to determine the uterine pregnancy using a transvaginal sensor already for a period of 2.5–3 weeks from the moment of conception. This corresponds to about the third or fifth day of the delay in menstruation. Therefore, the very first ultrasound examination is done specifically to establish the fact of pregnancy. At such an early stage, the doctor can also identify a number of symptoms of a threatened abortion and prescribe treatment in a timely manner.