Any of several methods used to demonstrate whether or not a woman is pregnant. Most pregnancy tests are based on the detection of a hormone, human chorionic gonadotrophin (hCG), in the urine. The sample of urine is mixed with serum containing antibodies to hCG and marker particles (sheep red cells or latex particles) coated with hCG. In the absence of pregnancy, the antibodies will cause agglutination of the marker particles. If the urine is from a pregnant woman, the antibodies will be absorbed and no agglutination will occur. These tests may be positive for pregnancy as early as 30 days after the date of the last normal period and are 98% accurate. Newer tests using monoclonal antibodies (beta hCG) are more easily interpreted. When carried out on serum rather than urine, these tests give even earlier positive results.
Subjects: Medicine and Health.