Definition The consensus synthesizes the views of national and international experts and defines syphilis serofixation as a patient with syphilis who has undergone standardized anti-syphilis treatment and adequate follow-up (1 year for stage I syphilis, 2 years for stage II syphilis, and 3 years for advanced syphilis) and whose non-syphilis spirochete serologic test has been maintained at a certain titer (usually 1 : 8 or less, but more than 1 : 8 is not uncommon) for more than 3 months, excluding reinfection, neurosyphilis, cardiovascular syphilis, and biological false positives. Syphilis serum is fixed when neurosyphilis, cardiovascular syphilis and biological false positives are excluded. Epidemiological consensus indicates that the prevalence of syphilis serofixation is high: 3.80% to 15.20% for stage I syphilis, 11.64% to 35.80% for stage II syphilis, 45.02% to 45.90% for stage III syphilis, and 27.41% to 40.50% for latent syphilis. This shows that serum fixation of syphilis has become a more difficult clinical problem. The possible mechanisms of syphilis serofixation, as summarized by consensus, include: alteration of syphilis spirochete membrane peptide antigens, lipoproteins and genes leading to inability to be cleared by the body’s immunity, abnormalities in the body’s immunity, including immune imbalance and immunosuppression, and disturbance in the secretion of T cell subsets, NK cells and cytokines. Prognosis There is consensus that persistent positive syphilis serology has mainly psychological and psychiatric effects on the patient. However, there is insufficient evidence-based medical evidence to assess the harmful effects of syphilis serofixation, and it is uncertain whether syphilis serofixation increases the risk of recurrence or progression to advanced syphilis, or whether additional penicillin therapy is beneficial. Treatment pathways Consensus has led to the development of treatment protocols for syphilis serofixation, including: A detailed history at the time of initial syphilis treatment, including history of sexual contact (time of infection, partner’s syphilis status, recent risky sexual behavior, etc.), history of previous treatment (time of initiation of treatment, type of drug used, duration, dosage, follow-up, etc.), in order to anticipate the patient’s post-treatment serologic response. During follow-up, cerebrospinal fluid examination is recommended to exclude neurosyphilis for those identified with syphilis serofixation, repeatedly if necessary. HIV testing should also be performed to rule out HIV infection. Cardiovascular syphilis and other visceral syphilis should also be excluded by appropriate testing. False-positive syphilis serology should also be excluded. Patients with serofixation of syphilis need to be analyzed and counseled. Patients who have received adequate anti-syphilis treatment and adequate follow-up, if there is no recurrence of clinical symptoms, neurological examination, cerebrospinal fluid examination and other relevant tests to exclude neurological and other visceral systemic damage, and if the non-syphilis spirochete serology test is maintained at a low titer of 1:8 for a long time, treatment is not necessary, but regular follow-up (usually every 6 months) is required. It is recommended to add syphilis spirochete-specific IgM antibody testing as a marker of syphilis recurrence and reinfection if available. A 4-fold or higher increase in non-syphilis spirochete serologic test titers during follow-up indicates recurrence or reinfection and requires re-treatment. Patients with syphilis serostasis need to weigh the pros and cons of pregnancy, and if they are pregnant, they need to be followed up regularly and, if necessary, preventive treatment can be considered, i.e., syphilis in pregnancy is treated according to the norms for syphilis in pregnancy. Studies have shown that treatment of pregnant syphilis patients with a standardized anti-syphilis regimen can prevent congenital syphilis in 98.5% to 100% of cases.