Real-time microscopic visualisation: current applications and challenges of confocal laser endomicroscopy in the diagnosis and treatment of small bowel disorders

Small bowel disorders often present insidiously, with early symptoms being non-specific. Moreover, the small intestine's unique anatomical position renders it difficult to access using conventional examination methods, frequently leading to delays in the diagnosis and treatment of small bowel disorders. Confocal laser endomicroscopy (CLE), as an emerging technique based on confocal microscopy, enables high-resolution assessment of gastrointestinal mucosa at cellular and subcellular levels. It provides real-time imaging, thereby achieving an 'optical biopsy'. The application of this technology not only enhances the ability to identify early lesions and dysplasia but also addresses the limitations of traditional endoscopic biopsy techniques - such as poor targeting and low efficiency of random biopsies - by guiding targeted biopsies. While its potential in digestive diseases is significant, particularly as an adjunct to histopathology, its application in the small intestine is still emerging. Current obstacles, such as procedural complexity, high equipment costs and a lack of specific diagnostic criteria, limit its widespread use. This narrative review synthesises findings from studies published since 2005 to critically evaluate the role of CLE in conditions including inflammatory bowel disease, functional bowel disorders and small bowel polyps, providing a balanced perspective for future research and clinical translation.