Endoscopes should be evaluated before and after every procedure in order to identify damage to the equipment and avoid potential failures during use. The following evaluation tips can be used to identify equipment failures.Visual Inspection: After every procedure, the image should be checked for clarity. This evaluation is best performed by holding the tip of the scope approximately three inches away from a non-glaring piece of printed paper and then slowly moving the tip to within a quarter inch of the paper. The printed image should appear clear and sharp without any distortions. While looking through the endoscope, rotate it which makes it easier to identify any defects.If you have access to a magnifying glass or loupe, carefully inspect the distal and proximal windows for cracks, scratches or debris. Holding the loupe up to the eyepiece and bringing the loupe close to your eye, gradually pull the endoscope away from your eye and look for dirt, moisture or broken lenses in the endoscope. Also, visually check to see if the image is round and if not, chances are the endoscope is bent or has broken lenses.By holding the light post up to a light, you can look at distal end for "peppering" or black dots which would indicate broken light fibers in the endoscope. Once approximately 20% of the light fibers are broken causing discoloration or shadowing, the endoscope should be sent in for repair as adequate light transmission is no longer possible.Shaft Inspection: Inspect the tubing (shaft) to ensure it is straight by rotating it on a flat surface while watching for signs of warping, or bends. Check the shaft for sharpness at the distal tip by rubbing the tip against your thumbnail and if it scratches your nail, then it is too sharp. Run your hand down the shaft to feel for any significant dents which might prohibit the endoscope from easily entering a sheath (cannula) or cause damage to the internal components such as fiber optics and / or lens systemCamera Focusing: In order to focus the image, first attach the rigid endoscope to a camera and then using the United States Air Force 1951 transmission type resolution target, focus from one extreme to the other until the target image is clear and crisp. Should a good image not be seen, change the endoscope to eliminate the cause being the camera and / or coupler.Eccentricity Inspection: This requires looking though the endoscope at an image to ensure the optic axis is centered. In the event of a bent shaft or attachment, the outer edge of the image will appear dark or a portion of the image will be lost. (The bend will always be opposite the dark side of the image.)A shortened endoscope, wrong objective lens or improper internal spacing between lenses will also generate shadows or the loss of a portion of the image.Leak & Condensation Testing: It is important to evaluate the endoscope for moisture before and after each procedure and always after the endoscope has been serviced. This is accomplished by looking through the endoscope for optical image distortions. This outcome can occur during a procedure when a cool endoscope is introduced inside the warm patient body cavity resulting in condensation forming on the optical lenses distorting the image.The leakage of fluid into an endoscope can have a devastating effect. Leaks are usually the result of adhesive and / or seal failure, and mechanical damage to the optic housing which is often caused by mishandling or heating the endoscope above manufacturer's specified temperatures. Another source leading to leaks / moisture invasion is cracking between the metal housing and optical elements. Once fluids invade the optical assembly, the moisture will be deposited on the lens surface and will obscure the image.Light Fiber Inspection: The function of light fiber bundle is to illuminate the working area of the endoscope. The light fibers run parallel to the inner tubing housing the optical lens assembly. At the distal end, these fibers will intentionally bend to match the direction of view (except for zero degree endoscopes.)Incorrect polishing of the objective lens and / or light fiber bundle at the tip may result in the removal of the angled fibers causing the light path to differ from the direction of view. In addition, abusive handling of the endoscope can lead to broken fibers or fluid invasion making the fibers brittle and prone to breakage reducing the intensity of illumination. These events would cause a partial visible loss or shadowing of the image. Hooking the endoscope to a light source and focusing the image on a stated target will indicate any potential issues associated with the illumination of the image. For best results, a light meter should be used and will more specifically indicate an event requiring the endoscope to be sent in for repair due to insufficient light transmission.Distal End Inspection: Today lasers are used in many surgical procedures and when the laser comes in contact with the distal end of the rigid scope, it often leads to damage. Carefully inspect the end of the rigid endoscope for laser burns and / or other damage caused to the shaft or lens.
