Courtney, a 34-year-old, suspects that she is pregnant. A serologic immunoassay test is performed to determine if she is pregnant. Which of the following statements is true about the test?
• All serology pregnancy tests are designed to detect human chorionic gonadotropin (hCG), which is a glycoprotein hormone secreted by the developing placenta shortly after fertilization. In a normal pregnancy, a qualitative serologic test detects the presence of the hCG hormone found in the serum and urine of pregnant women just 7-10 days following fertilization.
• The appearance of hCG in urine soon after conception and its subsequent rise in concentration during early gestational growth make it an excellent marker for the early detection of pregnancy. Even some over the counter home pregnancy urine tests can detect as little as 6.3 mIU/mL of hCG in urine, an amount which varies widely, but may be present anywhere from 3-9 days before a missed period.
• A quantitative immunoassay test measures the concentration of hCG, indicating the age of the baby. This test also screens for abnormalities that would give an abnormal hCG level like ectopic pregnancies, molar pregnancies, or possible miscarriages.
• Random urine specimens are appropriate for urine hCG testing (not serologic), but the
• Serologic tests require a blood sample, not urine.
• Over-the-counter urine tests (not serologic tests) can give false negatives because any low result will be negative, which can mean simply that the embryo has not yet implanted or developed enough to produce the minimum amount of hCG to meet the sensitivity requirements of the test.