Chromoendoscopy and intravital staining techniques.

Chromoendoscopy and intravital staining techniques are synonymous methods for the endoscopic early detection of malignant changes in the intestinal tract. Endoscopic intravital staining involves the use of absorptive stains (methylene blue and Lugol's solution), contrast stains (indigo carmine) and reactive stains (Congo red). Lugol's iodine solution is used to identify superficial carcinomas in the squamous epithelium of the oesophagus. Methylene blue stains the specialized intestinal epithelium in Barrett's oesophagus and, in addition to this, is helpful in the diagnosis of dysplasia. Intravital staining with indigo carmine contributes to contrasting and accentuating changed mucosal processes. Together with Cresyl violet, contrast staining is particularly important in detecting small, early malignant changes in the colon. The use of chromoendoscopy enables a biopsy diagnosis of superficial dysplastic changes and an accurate delineation of carcinomatous areas. In conjunction with the modern video-endoscopy (high-resolution endoscopy and magnification endoscopy), vital staining forms the diagnostic foundation for the detection of early malignant changes in the gastrointestinal tract. These techniques are therefore prerequisites to local endoscopic tumour therapy (mucosectomy). Despite their increasing acceptance, these methods must prove their diagnostic merit in randomized studies.