The optimal timing and effectiveness of a transparent cap in the endoscopic removal of bony foreign bodies from the esophagus

Introduction: Endoscopic removal of a bony foreign body is accompanied by risks, such as perforation. The use of a transparent cap attached to the tip of the endoscope has become an increasingly recommended technique for removing esophageal foreign bodies. However, its effectiveness specifically for bony foreign bodies remains uncertain, as does the optimal timing for cap application. This study aimed to investigate the effectiveness and the optimal timing of a transparent cap. Methods: From January 1, 2010-May 30, 2025, patients with reported bony esophageal foreign body for endoscopic removal were retrospectively analyzed. The primary outcome was the technical failure rate of endoscopic removal of a bony foreign body. Results: A total of 595 patients with bony esophageal foreign bodies underwent endoscopic removal during the study period: 216 underwent the transparent cap-assisted method and 379 underwent the conventional method. Among these foreign bodies, fish bones accounted for the majority (91.4%). The endoscopic failure rate of bony foreign body removal was lower in the cap-assisted group than in the conventional group (3.2% vs 7.9%, P =0.022). Subgroup analysis demonstrated the incidence of esophageal erosions and ulcerations was higher in patients who underwent endoscopy withdrawal for capping than in those who received capping prior to the exam (58.5% vs. 32.8%, P <0.001). Conclusion: The use of a transparent cap is an effective method to reduce the technical failure rate for endoscopic removal of an esophageal bony foreign body. Applying the transparent cap before the start of the endoscopic examination reduced the complication rates.