What Does a Negative Test Result Mean?

In medical tests, generally speaking, a negative result indicates normality, while a positive result suggests the presence of a disease or virus. However, not all negative results represent normality. For instance, a decrease or negative result in fructose content in semen can lead to insufficient sperm motility, causing infertility, which is abnormal. In blood type testing, the majority of Han Chinese have a positive Rh blood type. If the Rh blood type is negative, it is considered rare blood, often referred to as "panda blood". A negative test result usually indicates normalcy. Under normal conditions, test results are typically negative. For example, in urine protein testing, a negative result usually suggests a low protein content in the urine. Similarly, in fecal occult blood testing, a negative result indicates the absence of blood in the stool. Furthermore, a negative result for hepatitis B surface antigen suggests the absence of hepatitis B virus infection. A negative experimental result can indicate that a certain component is not detected or its content is very low in the test. For instance, if certain substances are excreted in trace amounts within the normal range or undetectable by routine methods, they can be considered negative, such as in qualitative tests for urine sugar and urine protein. If a certain substance is not found, such as no cells or parasite eggs detected in microscopic examination of urine or feces, it can be recorded as "microscopic examination: -". Many antigen or antibody tests also habitually use negative to indicate normalcy. For example, if hepatitis B virus has not infected a person and the corresponding antigen cannot be detected, the hepatitis B surface antigen (HBsAg) will be negative; a negative result for the syphilis spirochete antibody test indicates no syphilis infection; a negative screening test for HIV antibodies (HIVAb) suggests no HIV infection, and so on. A negative result in bacterial culture indicates the absence of pathogenic bacteria growth in the sample, rather than the absence of normal flora. Overall, negative test results can provide reassurance to patients and exclude the existence of certain problems.