What are the symptoms and manifestations of a biochemical pregnancy?

　　Under normal circumstances, the main symptoms and manifestations of biochemical pregnancy include vaginal bleeding, early pregnancy reactions, amenorrhea or irregular vaginal bleeding, disappearance of the gestational sac, changes in serum human chorionic gonadotropin (hCG) levels, and others. A detailed analysis is as follows:

　　1. Vaginal Bleeding

　　During a biochemical pregnancy, patients typically experience vaginal bleeding similar to menstruation. The amount of bleeding may be close to that of normal menstruation or slightly less. During the bleeding, grayish-white membranous material may also be observed flowing out.

　　2. Early Pregnancy Symptoms

　　Although a biochemical pregnancy does not result in a viable pregnancy, patients may experience transient early pregnancy symptoms such as nausea, vomiting, and aversion to greasy foods due to a temporary rise in serum hCG levels.

　　3. Amenorrhea or Irregular Vaginal Bleeding

　　Some patients may experience amenorrhea or irregular vaginal bleeding, with delayed bleeding resembling a menstrual period, although the amount of bleeding is usually not particularly heavy.

　　4. Disappearance of the Gestational Sac

　　After experiencing a biochemical pregnancy, patients undergoing abdominal ultrasound or transvaginal color Doppler ultrasound may fail to detect the presence of a gestational sac.

　　5. Changes in Serum hCG Levels

　　In biochemical pregnancies, serum hCG levels rise, but the increase is typically modest and does not exhibit the doubling pattern seen every other day in normal pregnancies. As vaginal bleeding occurs, serum hCG levels gradually decline to normal levels.

　　It is recommended to check the quality of sperm and eggs before pregnancy and to undergo routine gynecological examinations to ensure good health in both partners. Additionally, folic acid should be taken during the preconception period to reduce the likelihood of biochemical pregnancy.