Ectopic pregnancy is mainly when the fertilized egg does not reach the uterine cavity to settle, and in turn settles in the fallopian tube. It usually occurs within one week after the union of the sperm and the egg, that is, about three weeks from the last menstrual period. However, it is not detectable at this time and the only way to make a preliminary diagnosis is by taking a blood test for HCG. To confirm the diagnosis of ectopic pregnancy, an ultrasound should be done at 40 days of pregnancy, that is, 40 days after the last menstrual period. If no gestational sac is found in the uterine cavity and an inhomogeneous mass is found in the adnexal region, this indicates a high probability of ectopic pregnancy. For patients who are unsure, further clarification can be made by dynamic observation of the repeat blood HCG and ultrasound. Moreover, ectopic pregnancy may cause vaginal bleeding because of the poor location of its implantation, which may lead to poor development of the fertilized egg, resulting in preterm miscarriage and irregular vaginal bleeding, as well as vague pain in the left or right lower abdomen in some patients.