There are two major types of flexible laryngoscopes:
fiberoptic technology
chip-on-tip technology
Types of anatomy and function seen with the flexible scope not available with rigid scope:
palate closure
panoramic functional view of pharynx
swallowing evaluation
detailed view of anterior commissure even when epiglottis is overhanging
detailed view of anterior larynx when larynx is topically anesthetized and the flexible scope is placed in the posterior larynx and angled directly anteriorly
laryngeal ventricles
subglottic view
tracheal view
mainstem bronchi view
transtracheal view of subglottis when tracheostome present
When choosing a flexible endoscope there are a number of considerations.
Diameter of scope
Curvature of tip
Distance of curvature from tip
These considerations affect how easy it is to pass the endoscope through the nose. Endoscopes larger than 4 mm in diameter can be difficult to fit in a fair number of individuals or require a lot of decongestion and topical anesthesia to get them through. This takes added time for the examination. A smaller radius of curvature at the tip and a radius that is nearer the tip allows more freedom of movement in the narrow confines of the pharynx and larynx.
Fiberoptic scope tip flexibility and distance from tip matter when maneuvering within the larynx. Upper endoscope: long tip and uneven articulation. Lower endoscope: even radius curve near the tip allows close insertion into the larynx parallel to the true vocal cords
Larger endoscopes transmit more light. They allow for a working channel to be present.