Endoscopic clip systems for hemostasis and defect closure in gastrointestinal endoscopy

Table 2 Limitations of through-the-scope clips

Limitation	Description
Mechanical factors
Shallow bite with mucosal capture only	Scarred or edematous bases (e.g., fibrotic ulcers, post-ESD beds) reduce tissue grip, so closure or hemostasis may be unreliable - particularly for larger defects (> 10-15 mm) or tangential targets. In these settings, OTSC or suturing may be preferable than TTS[10,61]
Device or handling constraints	Some TTS clips are one-shot at deployment (limited recapture) and with imprecise rotational control. Likewise, multiple clips increase time, cost, and lumen clutter, hindering additional therapy[2,11]
Misfires resulting to technical and safety risks	Misfires resulting to opposite-wall capture or serosal injury can occur with off-axis closure. In addition, accessories may be entrapped (e.g., loop/snare) or mucosa torn if traction is applied after partial closure
Clip migration and dwell time variability	Clips usually detach within weeks (animal and clinical data often cite 1-4 weeks), but prolonged retention can occur (reports up to 3-5 years), which may also create MRI-compatibility considerations depending on the clip[14,62-64]
Lesion factors
Difficult access or angle	Locations such as the cardia, lesser curve, and posterior duodenal wall limit perpendicular apposition and precise jaw placement; long/looped positions also cause suboptimal rotation[2]
Brisk bleeding and clot burden	Active arterial bleeding can obscure the field and prevent adequate tissue capture; thermocoagulation or combination therapy is preferred when clip compression alone is insufficient[2,11,34]
Large vessels and wide defects	Clip compressive force may be inadequate for thick-caliber bleeding vessels or defects > 1-2 cm, where OTSC or even suturing has higher durable success[10,61]
Performance in specific etiologies	For colonic diverticular bleeding, meta-analyses show higher early rebleeding with clipping vs EBL, underscoring TTS limitations in these types of lesions[35]

TTS: Through-the-scope; ESD: Endoscopic submucosal dissection; OTSC: Over-the-scope clip; MRI: Magnetic resonance imaging; EBL: Endoscopic band ligation.