What is HCG test?

HCG testing is a medical diagnostic method that determines pregnancy or monitors related health conditions by detecting the level of human chor gonadotropin (HCG) in the human body.

Here is a detailed explanation of HCG testing:

I. Biological characteristics of HCG and source: HCG is a glycoprotein hormone secreted by the cytotrophoblast cells of the placenta. After a woman becomes pregnant, the fertil egg implants in the endometrium of the uterus,

and the placenta begins to form and secrete HCG. Physiological functions: Maintain corpus lute function, promote progesterone secretion, and support early pregnancy. Regulate the development of the fetus-placenta unit to ensure normal embryonic growth. ion pattern: HCG secretion begins 6-8 days after fertilization, with initially low levels. In the early stages of pregnancy, HCG levels double every48-72 hours), reaching a peak at about 8-10 weeks and then gradually declining, maintaining until delivery.

II. Principle of HCG testingAntigen-antibody reaction:

HCG testing uses specific antibodies that bind to HCG in urine or blood, judging the presence or absence of HCG and its concentration a colorimetric reaction (such as a test strip changing color)

or instrumental detection (such as a blood test). Test types: Qualitative testing: Determines you are pregnant (positive/negative), commonly used in home pregnancy test strips. Quantitative testing: Measures the specific concentration of HCG (mIU/mL) used to monitor embryonic development, rule out abnormal pregnancies (such as ectopic pregnancy, hydatidiform mole),

or assist in the diagnosis of certain tumors (such choriocarcinoma).

III. Uses of HCG testing

Early pregnancy diagnosis: HCG can be detected as early as 7-1 days after fertilization through a blood test, and a urine test is usually performed 7 days after a missed period. Highly sensitive tests can detect HCG levels as low 25 mIU/mL. Monitoring abnormal pregnancies: Ectopic pregnancy: HCG levels increase slowly, and a combination of ultrasound can make a diagnosis Hydatidiform mole: HCG levels are abnormally high, requiring further examination. Assessment of the risk of miscarriage: A decline in HCG levels indicate abnormal embryonic development or miscarriage. Tumor diagnosis and follow-up: Certain reproductive cell tumors (such as choriocarcinoma, testicular) will secrete HCG, and detecting its level is helpful for diagnosis and monitoring treatment effects.

IV. Methods of HCG Testing

Urine Test (Home Pregnancy Test): Advantages: Convenient,, low cost. Steps: Collect first-morning urine (when HCG concentration is highest). Dip the test strip into the urine or apply urine the designated area. Wait 3-5 minutes to read the result (two lines indicate a positive result, one line indicates a negative result). Precautions: void excessive water intake to dilute urine. Follow the instructions carefully to avoid contamination or expired test strips. False negatives may occur due to testing too early or urine dilution and false positives are rare but may be caused by medications (such as fertility drugs) or diseases. Blood Test (Hospital or Clinic): Advantages: High sensitivity quantifiable, earlier detection time (6-8 days after fertilization). Types: Qualitative blood test: Confirms pregnancy. Quantitative blood test (βHCG): Measures specific concentrations for dynamic monitoring. Application scenarios: Frequent HCG testing is required when suspected ectopic pregnancy or hydatidiform mole. embryo implantation status after assisted reproductive technology (such as IVF).

V. Precautions for HCG Testing

Testing time: Urine test: More accurate a 7-day delay in menstruation; testing too early may miss a diagnosis. Blood test: Can be detected 6-8 days after fertilization, but is usually recommended to wait until the expected menstrual date. Interpretation of results: A positive result needs to be confirmed by B-ultrasound to rule outopic pregnancy or hydatidiform mole. If a negative result is suspected to be pregnant, it can be retested after 2-3 days or directly undergo a blood. Special cases: Taking fertility drugs (such as clomiphene) may affect the results, and it needs to be informed to the doctor. Some (such as pituitary diseases, thyroid diseases) may cause HCG false positives, and further examination is needed.