The term ‘serology’ refers to the analysis of serums, how they react together and the different types. When applied to blood, serological detection refers more specifically to the serums found in blood and whether one person’s blood serum is compatible with another’s (as seen in transfusion). The success of blood transfusions improved greatly upon the discovery of blood types and the test to determine a person’s blood type, but it wasn’t until 1937 that the discovery of serological testing for th Rh antigen made blood transfusions totally safe. This process allowed medical professionals to determine whether a person is Rhesus negative (Rh-) or Rhesus positive (Rh+). Serological detection isn’t just used to determine whether a person is Rh+ or Rh- however. A test of this kind will be carried out if a certain infection or condition is suspected by a medical professional. Certain conditions cause the body to produce specific antigens, which can only be detected in serological testing. If that particular antigen is found using the test then the appropriate treatment can be taken. If this is a blood transfusion then the results of the serological testing will also indicate what blood type is required.