[Diagnosis and management of severe adverse events occurring during BCG therapy for non-muscle invasive bladder cancer (NMIBC)].

BCG therapy, which is the standard treatment for non-muscle invasive bladder tumours with high risk of recurrence and progression, has potential life-threatening adverse effects (AEs). Rapid deterioration of general condition in a patient with history of bladder tumour should question about an ongoing treatment with BCG and specify the date of the last instillation. Trauma during catheterization and untreated concomitant urinary infection upon instillations are risk factors of severe AEs. In emergency, the diagnosis of severe AEs of BCG therapy is only based on the medical questioning with the notion of current BCG treatment and risk-bearing event upon instillation. Management of AEs is related to their pathophysiological mechanisms and relies on a combination of antibiotics against BCG, the symptomatic treatment, and corticosteroid therapy which has shown to improve patient outcomes.