The effect of endoscopic sheaths on visualization in distal chip and fiberoptic laryngoscopy

Endoscopic sheaths covering the laryngoscope are advised to prevent cross contamination, but might hamper visualization as the most important tool in the diagnostic approach of laryngeal disease. We evaluated whether endoscopic sheaths change image quality and diagnostic accuracy of flexible distal chip laryngoscopy (DCL) and flexible fiberoptic laryngoscopy (FOL). Twelve healthy volunteers underwent a flexible laryngoscopy using a distal chip and a fiberoptic laryngoscope with and without endoscopic sheaths, and in this way 48 images were collected. To determine diagnostic accuracy, the 48 images were mixed with images of 40 patients. All images were randomly shown to four experts in the field of laryngology and head and neck oncology. Observers were asked to validate image quality, choose a diagnosis, and express their confidence level of that diagnosis. Image quality was validated better in DCL as compared to FOL (p <0.05) both with or without endoscopic sheaths. Endoscopic sheaths worsened image quality in DCL (p <0.05) but not in FOL. No differences were observed between DCL and FOL with or without endoscopic sheaths in diagnostic accuracy (79-89 %). Confidence levels (7.7-8.1) were comparable in DCL and FOL and not influenced by endoscopic sheaths. Image quality in DCL is superior to FOL, but significantly hampered by the use of endoscopic sheaths. In FOL the image quality is already low and not further diminished by endoscopic sheaths.