For esophagogastric anastomotic leakage complicated with mediastinal abscess after proximal gastrectomy, management should focus not only on leak closure or drainage of pleural effusion, but more importantly on timely control of the mediastinal infection source adjacent to the anastomosis. Endoscopic trans-fistula catheter drainage may provide a direct route for mediastinal source control in selected patients with a clearly identified defect communicating with a localized mediastinal abscess, especially when conservative treatment or pleural drainage alone is insufficient. Careful preprocedural imaging, gentle low-resistance catheter placement, adequate external drainage, dynamic irrigation management, and strict tube identification are essential for this technique.