Doubling of HCG every other day does not rule out ectopic pregnancy 100% of the time, but only 80% of the time. In 20% of cases of ectopic pregnancy, the doubling of HCG can also occur when the gestational sac is more active. Therefore, the HCG alone cannot accurately determine whether a patient is pregnant intrauterine or ectopic, but must be combined with other clinical symptoms, signs, laboratory tests and ultrasound examinations to make a comprehensive judgment. If the HCG doubles well every other day, progesterone is more than 25ng/ml, there is no abdominal pain or vaginal bleeding, when the HCG is more than 2000mIU/mL, and the intrauterine gestational sac can be seen on ultrasound, intrauterine pregnancy can be confirmed. When the patient has a good doubling of HCG, but the progesterone is less than 15ng/ml, the patient has abdominal pain or vaginal bleeding, and the HCG is greater than 2000mIU/mL, but the presence of the gestational sac cannot be observed on ultrasound, it indicates the possibility of ectopic pregnancy.