A 31-year-old patient underwent LSG in October 2024. Seven days later, CT imaging showed a perigastric fluid collection. Endoscopy identified a small distal staple-line defect with a large adjacent collection, and a double-pigtail stent was placed and removed two months later. In February 2025, the patient presented with fever and abdominal pain. CT demonstrated an 11 × 3 × 8.5 cm collection communicating with the distal staple line and extending through a fistulous tract to the left flank. Endoscopy revealed a 10 × 10 cm cul-de-sac with a small defect releasing purulent fluid. Direct endoscopic suturing with OverStitch NXT™ was performed to close the cavity and seal the fistula. In the following days, inflammatory markers decreased and symptoms resolved. A one-month CT scan showed marked reduction of the collection.