Abstract: Objective To explore the pathogenesis of complications arising from bladder instillation of the BCG vaccine in order to provide data for clinical applications. Methods One case of multiple organ failure caused by intravesical instillation of the BCG vaccine was analyzed. Related literature was reviewed while the incidence, pathogenesis and clinical manifestations of this complication were analyzed. Results The patient was discharged from the hospital in better condition after symptomatic treatment, involving blood pressure elevation, anti-infection, anti-shock and anti-tuberculosis medications as well as rehydration. The related laboratory indicators of the patient improved. However, the possibility of disseminated tuberculosis could not be ruled out, and allergic reactions might also be involved, which needed to be studied. Conclusion Although the majority of patients are well tolerant of bladder instillation of the BCG vaccine, clinicians need to be alert to its the risk of sepsis.

Key words: Bacillus Calmette-Guérin, intravesical therapy, bladder cancer, multi-organ failure, sepsis, adverse reaction