Primary aortoenteric fistula after intravesical instillation of Bacillus Calmette-Guérin for bladder cancer.

Primary aortoenteric fistula is an extremely rare complication, and although its relationship with intravesical BCG therapy is anecdotal, it should be considered in patients with gastrointestinal bleeding who have previously undergone this treatment. Its diagnosis requires clinical suspicion, and its treatment should be carried out without delay. Long-term targeted anti-biotherapeutic treatment is a fundamental pillar for its management. Reconstruction with an antibiotic-impregnated silver prosthesis is a valid option in cases of controlled infection.