Ultrasound can check whether a patient is pregnant. There are three main methods to check whether a patient is pregnant in clinical practice: first, check the human chorionic gonadotropin to determine whether a patient is pregnant, as long as it is more than three times the normal value, the patient can be judged to be pregnant, and it is the most accurate and earliest method to check whether a patient is pregnant. It can be detected about 7-10 days after intercourse. Secondly, the accuracy of urine pregnancy test is not 100%, and it can be affected by many factors, so there can be false positive or false negative rate, after confirming pregnancy through urine test, blood test or ultrasound is needed to further confirm. Thirdly, ultrasound is the longest method to check the pregnancy of a patient. It is only when the patient is about 40 days pregnant that the ultrasound can clearly determine whether she is pregnant, and also whether the pregnancy is intrauterine or extrauterine.