The Types of Pregnancy Tests
Pregnancy tests primarily aim to detect whether a female is pregnant. They can be categorized into the following types based on detection principles, sample types, usage scenarios, etc.:
I. Classification by Detection Principle
Human Chorionic Gonadotropin (hCG) Detection
Core Principle: After pregnancy, placental trophoblast cells secrete hCG, which is excreted through blood, urine, etc. Pregnancy is determined by detecting hCG levels.
1. Specific Types:
1. Immunochromatography (Colloidal Gold Method): Commonly used in home pregnancy test kits/strips. Results are judged by color bands on the test strip (e.g., two bands indicate positive).
2. Enzyme-Linked Immunosorbent Assay (ELISA): A laboratory method using enzyme-labeled antibodies to bind with hCG, enabling quantitative or qualitative detection via color reactions.
3. Chemiluminescent Immunoassay: Employed in hospital laboratories with high sensitivity, allowing quantitative detection of hCG concentration for early pregnancy diagnosis or abnormal pregnancy monitoring.
2. Other Biomarker Detection (Less Common):
Detection of progesterone, estrogen, etc. These are less specific than hCG and usually serve as adjuncts to hCG testing.
II. Classification by Sample Type
Urine Testing
1. Home Pregnancy Test Kits/Strips: Easy to use. Collect morning urine (with higher hCG concentration), drop it on the test area, and results appear within 5–15 minutes. Suitable for self-screening.
2. Hospital Urine hCG Testing: Similar in principle to home tests but more standardized, reducing false positives/negatives.
Blood Testing
1. Serum hCG Testing: Measures hCG in blood via blood sampling, including qualitative (only determines pregnancy) and quantitative (measures specific values, e.g., "β-hCG").
2. Advantages: Detects pregnancy earlier than urine tests (about 7–10 days after conception) and aids in diagnosing ectopic pregnancy, threatened abortion, etc.
III. Classification by Usage Scenario
1. Home Self-Testing:
Such as pregnancy test kits/strips, with clear instructions for initial at-home screening. Results require clinical confirmation.
2. Medical Diagnosis:
1. Routine hospital checks: Include urine and serum hCG tests for confirming pregnancy, estimating gestational age, and monitoring pregnancy health.
2. Special scenarios: Rapid hCG testing for suspected ectopic pregnancy in emergency rooms or pregnancy screening for patients with abnormal vaginal bleeding in gynecology clinics.
IV. Classification by Result Presentation
1. Qualitative Testing:
Only determines "positive" (pregnant) or "negative" (not pregnant), e.g., home test kits and most urine tests.
2. Quantitative Testing:
Provides specific hCG values (e.g., "500 mIU/mL"), common in blood tests. It assesses pregnancy progression or abnormalities (e.g., poor hCG doubling may indicate embryonic development issues).
V. Other Special Types
1. Early Pregnancy Tests:
Highly sensitive products that detect pregnancy 1–2 days before the expected menstruation
2. Digital Pregnancy Tests:
Display "pregnant" or "not pregnant" on an electronic screen, or directly estimate gestational age (based on hCG levels) for more intuitive results.
Pregnancy tests core on detecting hCG (or other biomarkers) to determine pregnancy status. Home urine tests offer convenience, while blood tests are more accurate for medical diagnosis. Selection depends on needs (screening, confirmation, monitoring) and scenarios (home, hospital), with final confirmation requiring clinical exams .
