RPR is the English acronym for Rapid Plasma Reactin Test, which detects the presence or absence of reactive elements of anti-cardiolipid antigens in a patient’s serum and is used for syphilis patient screening and epidemiological investigations. The RPR test assists in the diagnosis of syphilis after the human body has been infected with the syphilis spirochete for a certain period of time and produces a certain amount of cardiolipin antibodies in the serum. The test is highly sensitive but low specificity, and when the result is positive, the clinical manifestations are consistent with syphilis and a preliminary diagnosis can be made. False negatives are commonly seen within 2-3 weeks after the appearance of stage I syphilis hard chancre, or late stage syphilis. False positives are common in autoimmune diseases, leprosy, heroin addicts, a few pregnant women and the elderly. positive RPR results have the following clinical significance: 1. preliminary diagnosis of syphilis: about 50% of patients with stage I syphilis will have a positive reaction, almost 100% of patients with stage II syphilis rash will be strongly positive, and about 75% of patients with late syphilis will be positive, so that early and late latent syphilis can be identified; 2. diagnosis of neurosyphilis The RPR can help to diagnose neurosyphilis by using cerebrospinal fluid test; 3, efficacy observation: the titer of RPR generally peaks at the second stage of syphilis, and then gradually decreases, if not treated in time, about half of the patients maintain a low level of titer for life; if treated immediately at the early stage of syphilis, it can effectively inhibit the formation of antibodies, so that the RPR value always remains negative, if the treatment is started only at the late stage of syphilis If treatment is started at the late stage of syphilis, the RPR titer will not decrease significantly and the treatment will be ineffective.