Effects of Fluid Invasion

Fluid entering the internal cavities of an endoscope may severely damage its components. Highly acidic or highly alkaline solutions will be more corrosive than water, but any fluid will do serious damage over time. Following is a breakdown of some of the major systems and components in a flexible endoscope and the typical damage resulting from fluid invasion.

Angulation – Corrosion of the angle knob and chain mechanism will cause the knobs to become increasingly difficult to operate. Corrosion and residue around the angle wires will increase the friction of the angulation movement. Corrosion and residue can also affect the angulation components at the distal end. Any of these cases might cause stiff, reduced or irregular movement.

ERCP Elevator System – The elevator system knob assembly may become stiff due to corrosion and residue build-up.

Fiberoptic and Light Bundles – Both light and image fiber bundles are affected in the same way.  Fluid stains the bundles, causing poor color light or no light transmission. The bundles also become very brittle and inflexible; when bent during normal scope use, the glass fibers break and light transmission decreases proportionately.

Insertion Tube/Light Guide Tube – Fluid invasion does not significantly affect the tubes. However, the fluid may be difficult to flush and remove completely without the skills of a trained technician. Any moisture remaining after a fluid invasion repair will be trapped inside and may cause the inner surfaces of the optical system to fog.

Optical Lenses – The objective lens assembly is the image-capturing lens group at the distal tip of the endoscope. It is made up of multiple lenses held together with clear glue. Fluid may break down this glue, causing lens separation and leading to severe image problems. Although surfaces of the endoscope are designed to withstand harsh, reprocessing fluids, fluid that builds up on the inner surfaces cannot be wiped off and often leaves a blurry image. 

Video Switches – The video switch electrical contacts have no protection from fluid that has entered the scope. Their surfaces are exposed and corrode easily. Corroded switches will either not operate or they will operate constantly without any stimulation.

Adhesives – External adhesives found on endoscopes are designed to withstand harsh reprocessing chemicals. The adhesives used internally may not be able to withstand these same chemicals.

CCD Video Chip – The video chip is located near the distal tip of the flexible video endoscope. It is a delicate electronic component that will degrade quickly when exposed to corrosive fluids.

Electrical Video Connector – The electrical video connector (at the light guide connector) is a series of soldered electrical connections and circuit boards.  Fluid invasion causes corrosion of theses components and results in a variety of image and other electronic signal problems.

Light Guide Prong – The light guide prong is the longest of the connection points where the scope plugs into the light source. The light fiber bundle terminates here. Fluid in the scope will collect at the end of this prong and then be baked on when the scope is next plugged into the light source. This heated fluid leaves a dark residue on the inside surface of the light guide lens that reduces light transmission.

Biopsy/suction Channels – The biopsy and suction channel material is made to withstand fluid and is not affected by fluid invasion.

Air/water Channels – The air and water channel material is made to withstand fluid and is not affected by fluid.

 

 

Next Page: Leak Testing to Prevent Fluid Invasion

Fluid damages may be caused by water, chemicals, or human proteins.