Early diagnosis of pregnancy on ultrasound can be carried out starting from 2.5 - 3 weeks from the date of conception, i.e. starting from 3-5 days of delay from the expected date of arrival of menstruation. These dates are approximate and depend on the date of possible fertilization and the period of ovulation. With early ovulation, ultrasound can show pregnancy already from 2-4 days of delay, with late ovulation, it cannot be shown even with a week. This is just the option when a woman has a positive test, the hCG analysis shows, but the ultrasound does not. However, in the latter case, it is necessary to have a certain alertness regarding the ectopic localization of the embryo. Therefore, in case of any violation of the regularity of the menstrual cycle, it is necessary to make an appointment with a gynecologist without delay.