Maintenance of Gastrointestinal Endoscopes
Renee Shumway, LVT, and John D. Broussard, DVM, Diplomate ACVIM (Internal Medicine)
highly toxic. Strict protocols for reprocessing are necessary to
Endoscopes are used for visualization and biopsy of gastroin-
ensure infection control, and to avoid injury to personnel and
testinal lesions, as well as therapeutic procedures, such as
patients. Transmission of infection is difficult to recognize and,
foreign body retrieval. In the past, they were primarily used in
therefore, an infrequently reported complication of endoscopy.
large institutional settings where specialized personnel could
Microbial monitoring protocols are necessary to ensure ade-
focus on their maintenance. Today, they are becoming increas-
quate infection control.4,5
ingly common in general practice. The maintenance of gastroin-
testinal endoscopes in the veterinary setting involves many chal-
lenges, including safe handling, reprocessing, and storage.
Flexible Endoscope Structure and Function
Meeting these challenges requires well-trained personnel and
strict protocols. Reprocessing, which includes cleaning and dis-
There are many different kinds of flexible endoscopes used in
infection, offers the greatest challenge. The complex structure of
veterinary medicine. They differ between manufacturers and
flexible endoscopes, particularly the long, narrow channels,
even between models from the same manufacturer. However,
makes them difficult to clean. Gastrointestinal endoscopes op-
all flexible endoscopes have the same basic components. It is
erate in a contaminated environment, exposing them to high
helpful for personnel involved in the handling and reprocessing
levels of organic matter and bacteria. High-level disinfection is
of flexible endoscopes to have an understanding of their struc-
necessary for infection control, but liquid germicides available for
ture and function.2
endoscope disinfection can be toxic to medical personnel and
patients.
© 2003 Elsevier Inc. All rights reserved.
External Components
All flexible endoscopes have a light guide plug, an umbilical
cable (cord), a control section, and an insertion tube (Fig 1).
ver the last 30 years, gastrointestinal endoscopy has
Oemerged as an important alternative to invasive surgery in
Light Guide Plug
veterinary clinical practice. Endoscopes are used for visualiza-
tion and biopsy of gastrointestinal lesions, as well as therapeu-
The light guide plug fits into the light source. The air/water and
tic procedures, such as foreign body retrieval.1 In the past, they
suction channels have ports in the light guide plug. The light
were primarily used in large institutional settings where spe-
guide plug of a video endoscope is heavier than that of a non-
cialized personnel could focus on their maintenance. Today,
video endoscope and needs to be handled with care. The termi-
they are becoming increasingly common in general practice.
nals in the light guide plug of the video endoscope are not
The maintenance of gastrointestinal endoscopes in the vet-
waterproof and must be covered by the cap supplied with the
erinary setting involves many challenges, including safe han-
instrument before cleaning.2
dling, reprocessing, and storage. Meeting these challenges re-
quires well-trained personnel and strict protocols. Flexible
Umbilical Cable
endoscopes are complex instruments made of soft flexible ma-
The umbilical cable connects the light guide plug to the control
terials, with delicate optical, electronic, and mechanical com-
section of the endoscope.
ponents. They are prone to damage during use, reprocessing,
and storage. Protocols for all phases of handling endoscopes are
Control Section
necessary to avoid instrument failure.2
Reprocessing, which includes cleaning and disinfection, of-
The control section contains the angulation control knobs,
fers the greatest challenge. Gastrointestinal endoscopes operate
which allow the operator to manipulate the distal end of the
in a contaminated environment, exposing them to high levels of
instrument, and the suction and air/water valves. Nonvideo
organic matter and bacteria. Their complex structures, partic-
endoscopes have an eyepiece on the control section. Video
ularly the long, narrow channels, make them difficult to clean.3
endoscopes are similar in construction to nonvideo endo-
Delicate parts allow limited options for decontamination. High-
scopes, except that they do not have an eyepiece. The image is
level disinfection is necessary for infection control, but liquid
seen on a video screen. The biopsy channel port is located at the
sterilization agents used for endoscope sterilization can be
base of the control section, near its junction with the insertion
tube.
From the Bobst Hospital, Animal Medical Center, New York, NY.
Insertion Tube
Address reprint requests to Johns D. Broussard, DVM, Diplomate
ACVIM (Internal Medicine), Bobst Hospital, Animal Medical Center, 510
The insertion tube enters the patient s body and is grossly con-
East 62nd Street, New York, NY 10021.
taminated during the procedure. The distal end of the insertion
© 2003 Elsevier Inc. All rights reserved.
tube houses the microchip (in video endoscopes), the openings
1096-2867/03/1804-0008$30.00/0
doi:10.1016/S1906-2867(03)00000-0 for the suction and air/water channels, and the lens covering the
254 Clinical Techniques in Small Animal Practice, Vol 18, No 4 (November), 2003: pp 254-261
Fig 1. Endoscope structure. Reproduced with permission.6
flexible fiber optic light guides. The section of the insertion tube Suction/Biopsy Channel
adjacent to the distal end is known as the bending section. The
The suction/biopsy channel is basically a length of tubing run-
outer covering is made from soft, flexible material and is par-
ning from one end of the endoscope to the other, with an on/off
ticularly vulnerable to damage.2
valve in the middle.
Internal Components
Air and Water System
The air from the pump flows into the endoscope at the light
Angulation System
guide plug or water bottle. From here, it flows to the control
The angulation system is what makes the tip articulate when section of the endoscope and out the air/water valve. To inflate
the angulation knobs on the control head are rotated. It can be the organ being examined, the air/water valve is covered, which
broken down into 3 areas: (1) the control mechanism, (2) the diverts air down the insertion tube and out the distal tip. When
coil pipes, and (3) the bending section. the air/water valve is depressed, air entering the endoscope is
Control Mechanism. The control mechanism attaches the split with some of it diverted into the water bottle, which forces
angulation knobs to the angulation wires, which run the length water into another channel in the umbilical cable. The water
of the insertion tube. A locking mechanism allows these to be travels through the channel in the umbilical cable, through the
fixed in any position. air/water valve, and down the insertion tube to the air/water
Coil Pipes. These are flexible springs attached to the inner nozzle at the distal tip.2
wall of the insertion tube. The coil pipes house the angulation
wires and direct them in the proper direction. They also offer
Image System
protection to the internal elements from the sawing motion of
the wires, which are constantly in motion while steering the The image system is made up of a variety of components, in-
distal tip. cluding fiberoptics, electronics, and the lens system. The inter-
Bending Section. In the bending section, several metal nal structure of a video endoscope is virtually the same as a
bands are hinged together. When the control knobs are manip- nonvideo endoscope except for the imaging system.
ulated, the angulation wire is pulled up through the coil pipes. Lighting. Fiberoptic bundles composed of thousands of in-
As the wire is pulled, it causes the distal tip to bend in that dividual fibers transmit light from the light guide plug to the
direction. A combination of up/down and left/right allows the distal tip of the insertion tube. The flexibility of the fibers
tip to bend in any direction.2 enables the light to be bent around corners and curves.
MAINTENANCE OF GASTROINTESTINAL ENDOSCOPES 255
Nonvideo Imaging. Nonvideo endoscopes also use a fiber Reprocessing
bundle to transmit the image from the objective lens at the
Water damage is a major concern during the flushing and soak-
distal tip of the endoscope, through the eyepiece, to the user s
ing associated with reprocessing. It is necessary to leak test the
eye. The image guide bundles are set up so that each fiber
scope and apply protective caps over water sensitive electronic
carries a portion of the image and is in the same place at both
connections before cleaning. Cleaning solutions and liquid ger-
ends of the bundle. Video cameras attached to the eyepiece of
micides used during reprocessing have a potential to damage
fiberscopes are often used to display the image on a monitor.
endoscopes. Manufacturer warranties strictly limit the prod-
The final image is made up of the many, small pieces of the
ucts used in endoscope reprocessing. During storage, endo-
whole image. A broken fiber will result in a black or gray dot on
scopes must hang freely in a well-ventilated place to promote
the image.
drying. The safe handling of endoscopes during reprocessing
Video Imaging. In a video endoscope, the image bundle is
will be discussed further in the Reprocessing section.2
replaced with a video camera unit consisting of a lens assembly
and an electronic chip. Approximately 16 small wires connect
the electronic chip to an external video processor. The proces-
Reprocessing
sor assembles the image and transmits it to a video monitor.
Lens Systems. All endoscopes have lenses in both the light- The first major challenge of reprocessing is infection control.
ing and image systems.2 Most episodes of infection can be traced to procedural errors in
cleaning and disinfecting the endoscope or its accessories. This
includes inadequate mechanical cleaning, the use of substan-
Electrical System
dard disinfection solutions, inadequate drying before storage,
Electrical systems of fiberoptic scopes tend to be very simple,
or the use of contaminated accessories, such as water bottles.5,7
while video scopes are quite complex.
The presence of organic material, such as blood, feces, and
Automatic Brightness System. This controls the light level
respiratory secretions, can result in the failure of disinfection.
on all video endoscopes and some nonvideo endoscopes. Illu-
Organic material may protect microorganisms from exposure
mination decreases as you get closer to an object and increases
to the biocide, or the biocide may be inactivated by contact with
as you get further away. The brightness intensity is also affected
organic material. Consequently, rigorous cleaning of flexible
by the color, texture, and reflectivity of an image. The auto
endoscopes is required to remove such material before disin-
brightness compensates for these differences.
fection or sterilization. This should occur immediately after use
Switches. Video endoscope systems have the ability to cap-
to prevent the drying of secretions. The efficacy of cleaning and
ture information in several different media, including video-
disinfection is personnel-dependent; hence, training and qual-
tapes, computer files, and prints. The switches on top of the
ity control are critical for reliable reprocessing.7
control body are used to control the various recording devices
The second major challenge is to protect personnel and pa-
or change settings on the video processor.2
tients from the exposure to liquid biocides used for disinfec-
tion. Endoscopy personnel must be educated about the hazards
Safe Handling
of exposure to these potentially toxic chemicals.4,5 Gowns,
mask, and gloves are always recommended. The Society of
Transport
Gastrointestinal Nurses and Associates suggests that reprocess-
ing should not occur in the procedure room. However, in a
The control section of a flexible endoscope is the only part
small animal practice with limited space, this may not be pos-
designed to bear the weight of the instrument. During trans-
sible. If reprocessing must occur in the procedure room, it is
port, one hand should hold the control section, while the other
important to avoid cross contamination from the procedure
hand holds the ends of the insertion tube and umbilical cable.
area.7 Adequate ventilation is also needed to limit the exposure
The delicate optics at the tip of the insertion tube should be
of personnel and patients to toxic vapors. Copious flushing of
cupped in one hand to protect them from damage.1
the external surface and internal channels of the endoscope are
necessary to avoid exposure of patients to biocides during sub-
Procedures
sequent procedures.8 Endoscope reprocessing involves multi-
During procedures, there are many opportunities to damage ple steps (See Table 1).
endoscopes. Before procedures, external inspection for damage
and leakage testing should be performed. All functions of the
Precleaning
scope should be checked, including angulation, air/water, suc-
tion, light, and imaging. Angulation locks should be placed in The reprocessing of the gastrointestinal endoscopes is a time-
the open position. Flexible instruments should be checked for consuming endeavor. In an ideal setting, complete cleaning
damage and function to prevent damage to the working chan- should be performed as soon as the endoscopic procedure is
nel. During patient preparation and anesthetic induction, the finished. However, in the veterinary setting, cleaning can be
scope should be hung in a safe place. During procedures, scopes broken down into steps, freeing personnel to tend to other
tend to fall off tables when laid down, and the insertion tube responsibilities, such as recovering the patient from anesthe-
tends to slide out of the patient. For this reason, the control sia.1
section should be held at all times, and the insertion tube A person not recovering the patient from anesthesia should
should be stabilized while in the patient to prevent sliding. If preclean the scope. This should happen immediately after the
there is not adequate personnel to hold the scope at all times, scope is removed from the animal and before it is detached from
ample table space should be provided between the patient and the power source. Prepare a bowl of enzymatic cleaning solu-
the endoscopist.1 tion according to manufacturer instructions (see  Enzyme So-
256 SHUMWAY AND BROUSSARD
done to the interior or exterior of the scope during use. Due to
TABLE 1. Steps of Reprocessing
the gastrointestinal endoscopes delicate design, holes and tears
Pre-cleaning Disinfection of the inner lumen of the scope make it possible for water and
Suction enzymatic solution Immerse in disinfectant
other debris to contact otherwise impermeable areas of the
Wipe insertion tube Immerse removable parts
Brush instrument channel Flush channels scope. If damage is detected, the equipment should not be
External inspection Contact time
submerged or used.4,5
Visual inspection Purge channels with air
Leak testing Rinse To leak test, remove the scope from the light source, and
Protective cap (videoscopes) Rinse exterior
attach the protective cap over electronic connections of video-
Connect leak tester Rinse channels
Immerse in water Purge channels with air scopes. Attach the leak tester according to manufacturer in-
Mechanical Cleaning Alcohol
structions. Submerge the endoscope, and observe the insertion
Immerse in enzyme solution Flush channels
Detach removable parts Drying tube and the umbilical cable for bubbles from the interior of the
External cleaning Purge channels with air
scope. Flex the distal bending section of the insertion tube in all
Brush all ports Dry exterior
Brush channels (3 ways) Dry removable parts directions to assess for leakage in this area. Leak testing should
All channel irrigator Storage
be performed before immersion of the scope in the detergent
Clean removable parts Hang scope
Purge channels with air Store removable parts solution to avoid damaging parts of the endoscope not designed
Clean/Disinfect accessories
for chemical exposure. Follow manufacturer instructions if a
leak is detected or the endoscope appears damaged.7
lutions section). Place the distal end of the insertion tube in
Mechanical Cleaning
the solution. Suction the solution until it is visibly clean as it
passes through the scope into the suction tube. Alternate suc- The most important step in prevention of infection during
tioning the enzyme solution and air several times. Finish by endoscopy is manual cleaning.7 Organic soil (eg, blood, feces)
suctioning air. The instrument channel should be brushed to may contribute to the failure of disinfection by harboring em-
remove particulate matter.4,5 Wipe gross debris from the inser- bedded microbes and preventing the penetration of germicides.
tion tube with a sponge or gauze soaked in enzyme solution.7 Also, some disinfectants are inactivated by organic material.
The tip of the endoscope should be gently brushed to remove Rigorous mechanical cleaning to remove organic material from
any debris or tissue in or around the air/water nozzle.4,5 The the outside and all accessible channels is imperative before
endoscope is then safe to sit until time is available for complete disinfection or sterilization.4,5
reprocessing. Immerse the endoscope in freshly made enzyme solution.
Wash all debris from the exterior of the endoscope by brushing
Enzyme Solutions and wiping the instrument while submerged in the detergent
solution. Whenever practical, leave the endoscope submerged
Enzymatic detergents are designed to clean organic material
in the detergent solution when performing all subsequent
from medical devices. They are ideal for cleaning flexible endo-
cleaning steps to prevent splashing of contaminated fluid. De-
scopes and their accessories. The enzymes promote protein
tach the suction and air/water valves, the biopsy channel cover,
lysis, and enhance the efficacy of brushing and flushing. Check
and all other removable parts. The endoscope must be com-
the scope manufacturer recommendations when selecting an
pletely disassembled so that all surfaces may be reached for
enzymatic-cleaning product. Enzymatic detergents are an es-
thorough cleaning. Use a small soft brush and or lint-free clean-
sential part of mechanical cleaning but in no way replace the
ing swab to clean all removable parts, including inside and
disinfection phase of reprocessing.2
under the suction valve, air/water valve, and biopsy port and
Dilute the detergent according to manufacturer instructions.
openings. The use of nonabrasive and lint-free cleaning tools
Enzymatic solutions work most efficiently when warm, but
will prevent damage to the endoscope.7
enzymes will continue to be active when cooled to room tem-
Brush all accessible endoscope channels, including the body,
perature. Hot water will inactivate enzymes, and should not be
insertion tube, and the umbilical cable of the endoscope. For
used. Use fresh detergent solution for each endoscope to pre-
most scopes, this involves brushing in 3 directions: (1) working
vent cross contamination. Low sudsing detergents are recom-
channel to the insertion tip, (2) insertion tip to the suction
mended so that the surfaces can be clearly visualized during the
valve, and (3) suction valve through the umbilical cable.1 Use a
cleaning process. Excessive suds may also inhibit good fluid
brush size compatible with the channels. After each passage,
contact with endoscope surfaces. Gross debris should be me-
rinse the brush to remove any visible debris in the detergent
chanically removed because high levels of organic material will
solution before retraction and reinsertion of the brush. Con-
overwhelm the enzymes.7,8
tinue brushing until there is no debris visible on the brush.7
Where an enzyme product is not immediately available, a
Discard single use channel cleaning brushes. Reusable brushes
neutral instrument detergent can be used. Check with the en-
should be thoroughly cleaned and disinfected between cases.
doscope manufacturer for compatible detergents. Household
Reusable brushes should be inspected between uses and re-
detergents are generally not suitable. Chlorhexidine based de-
placed when worn, frayed, bent, or otherwise damaged. Broken
tergents have damaged instruments when followed by glutaral-
bristles are ineffective in cleaning, and damaged bristles may
dehyde disinfection, and should not be used.7
break endoscope channels.4,5
Next, attach the all channel irrigator, or cleaning adapters for
External Inspection and Leak Testing
the suction, biopsy, air, and water channels (refer to manufac-
At all stages of handling, the equipment should be inspected for turer instructions). Flush the channels with the detergent so-
damage, and a leak test should be performed before submerging lution to remove debris. Prolonged soaking of the channels in
the entire instrument. Leak testing ensures that damage was not the detergent solution may be beneficial if there has been a
MAINTENANCE OF GASTROINTESTINAL ENDOSCOPES 257
TABLE 2. Germicide Disinfection Level and Compatibility with Endoscopes7
Germicide Disinfection Level Manual Processing Olympus Pentax Fuginon
0.045% Chlorohexidine LLD C NC NC NC
Glutaraldehyde HLD C C C C
0.55% Ortho-phthalaldehyde (Cidex OPA) HLD C C C C
0.2% Peracetic Acid (Steris System 1) HLD NC NC C C
0.08% Peracetic acid/1% hydrogen peroxide (Cidex PA) HLD C NC NC NC
7.5% Hydrogen peroxide HLD C NC NC NC
Abbreviation: C, compatible; NC, not compatible; HLD, High-Level Disinfection; LLD, Low-Level Disinfection.
delay in beginning the cleaning process. Before immersion in manufacturer may result in cancellation of the endoscope s
disinfectant solution, all channels should be purged with air to warranty. The other product, 35% peracetic acid, is used only in
avoid dilution of the disinfectant.7 Meticulous, manual clean- automated reprocessing systems (See Table 2).2,8
ing must precede exposure to any disinfectant. Studies show Consider factors such as endoscope compatibility, toxicity,
that appropriate cleaning reduces the number of microorgan- environmental controls, and cost when selecting a disinfectant
isms and organic load by 99.9%. This significantly reduces the product. Thoroughly read the Material Safety Data Sheet
organic and microbial challenge to the biocide.8 (MSDS) for the chemical chosen, and follow all safety measures
for use. For more information on all these chemicals, refer to
Disinfection  Guideline for the Use of High-Level Disinfection and Sterilants
for Reprocessing of Flexible Gastrointestinal Endoscopes, by
Endoscopes have the potential to transmit infection between
the Society of Gastrointestinal Nurses and Associates Inc.8 The
patients. Reported iatrogenic infections include Escherichia
safe handling of these products requires strict protocols for
coli, Pseudomonas, Klebsiella, Serratia, and Salmonella.9 Other
storage, personal protective equipment, ventilation systems,
organisms of concern in gastroenterolgy settings include
and disposal. Gowns, gloves, and protective eyewear are rec-
Campylobacter, Clostridium difficile, and Helicobacter pylori, as
ommended when handling these chemicals. Appropriate venti-
well as many viral pathogens.3,8 Ideally, flexible endoscopes
lation is essential to avoid respiratory irritation and sensi-
should be sterilized between patients. However, because of
tization. Protocols for disposal are necessary to avoid environ-
their structural complexity and fragility, flexible endoscopes
mental contamination.8
cannot withstand available sterilization methods. Alternatively,
high-level disinfection is recommended as a minimum level of
Glutaraldehyde
reprocessing.10
High-level disinfection is a cleaning process that kills all A 2% glutaraldehyde has gained wide acceptance as a high-level
microorganisms except large numbers of bacterial spores. disinfectant and chemical sterilant. High-level disinfection is
High-level disinfection is the first level of disinfection below achievable with a 20-minute exposure at room temperature.8
sterilization, which kills all microorganisms, including bacte- Glutaraldehyde has excellent biocidal activity, is active in the
rial and fungal spores. Because they are not rendered sterile, presence of organic matter, and is noncorrosive to metals, rub-
endoscopes cleaned using high-level disinfection are consid- bers, and plastics. Olympus, Pentax, and Fujinon list glutaral-
ered  semicritical items. They may contact broken skin or dehyde as compatible with their endoscopes. Glutaraldehyde
mucous membranes, which are usually resistant to common products are marketed under a variety of brand names, and are
spores, but they should not contact vascular or other sterile available in a variety of concentrations, with and without sur-
body tissue. Endoscopic accessories that are used to enter tis- factants. For the reprocessing of endoscopes, a 2% glutaralde-
sue, such as biopsy instruments, must be sterile.2,7,10 hyde solution that does not contain surfactant is recom-
Low-level disinfection refers to a process that can kill most, mended.8 Alkaline 2% glutaraldehyde preparations (eg, Cidex,
but not all, vegetative bacteria, some viruses, and some fungi. Advanced Sterilization Products, Irvine CA) require  activa-
Low-level disinfection is not considered adequate for endo- tion to increase the pH to 7.5 to 8.5, to make the solution
scope reprocessing. This process does not reliably clear organ- sporicidal.2,8
isms such as Gram-negative rods and Gram-positive bacteria, Glutaraldehyde can be hazardous to humans and animals. It
which are frequent contaminants of gastrointestinal endo- can cause irritation to the skin, eyes, throat, and lungs, and can
scopes.2,8 Chlorhexidine is an example of a low-level disinfec- cause sensitization of the skin and respiratory tract. Once sen-
tant.11 sitized to glutaraldehyde, further exposure to even small
Five chemicals are currently approved by the Food and Drug amounts can lead to dermatitis, rhinitis, and conjunctivitis.12
Administration (FDA) as high-level disinfectants and/or steril- Failure to rinse disinfected equipment thoroughly, thus leaving
ants for reprocessing reusable medical devices.8 Only 2 of them, residual glutaraldehyde on the endoscope, has led to serious
glutaraldehyde and 0.55% ortho-phthalaldehyde (OPA), meet conditions, including chemical colitis, pancreatitis, and muco-
the needs of most veterinary practices. They are available for sal damage in human patients.2,8,12
manual reprocessing and are cleared by most endoscope man- Always use glutaraldehyde in a well-ventilated area, and wear
ufacturers for use. Olympus America, Inc (Melville, NY), Pen- gloves, mask, eye protection, and fluid resistant gowns. If ade-
tax Corp (Tokyo, Japan), and Fujinon, Inc (Wayne, NJ) have quate ventilation is not available, use a ductless ventilation
not determined that 7.5% hydrogen peroxide or 0.08% perace- device that contains filters to absorb glutaraldehyde vapors.
tic acid/1% hydrogen peroxide are compatible with their Latex gloves should be changed every 15 minutes while using
scopes.8 The use of a product not considered compatible by the glutaraldehyde. Using double gloves provides up to a 4-fold
258 SHUMWAY AND BROUSSARD
increase in permeation time compared with single latex gloves.8 eterious effects on plastics, aluminum, or stainless steel. How-
One hundred percent nitrile rubber or 100% butyl rubber ever, Olympus does not endorse the use of this chemical and
gloves are recommended for the best protection from glutaral- will not assume liability if chemical damage occurs.8
dehyde. Neoprene and polyvinyl chloride gloves are not recom-
mended because these materials absorb and retain glutaralde- Hydrogen Peroxide
hyde.8,13
A 7.5% hydrogen peroxide solution can be used as a high level
Glutaraldehyde spills small enough not to cause tearing of
disinfectant at room temperature for 30 minutes. However,
the eyes and/or respiratory discomfort can be cleaned up with a
hydrogen peroxide can cause damage to rubbers and plastics
mop, sponge, or towel. Discard the saturated item in a tightly
and can corrode aluminum, nickel-silver alloy and chrome-
sealed biohazard bag. Rinse surfaces thoroughly with water.
plated steel. Most endoscope manufacturers do not consider
Large spills may require neutralization with sodium bisulfite or
hydrogen peroxide compatible.
2% dibasic ammonium phosphate. Have one of these chemicals
available wherever glutaraldehyde is used. Be familiar with the
Peracetic Acid
MSDS recommendations for spill or leak procedures. In most
states, glutaraldehyde solutions that have failed Minimum Ef- A 0.2% peracetic acid solution is used in conjunction with the
fective Concentration (MEC) tests can be discarded down the automated reprocessing system, STERIS System 1 (STERIS
drain and flushed with large amounts of water. Triple-rinse Corp, Mentor, OH). This product is not available for manual
empty containers from freshly activated solutions with water reprocessing and is unlikely to be cost-effective in veterinary
before disposal. Consult state and local regulations for possible practice. Pentax and Fujinon list the STERIS System 1 as com-
differences in disposal requirements.8,12 patible with its endoscopes. Olympus does not support the
product but continues to conduct studies.8
Ortho-Phthalaldehyde (OPA)
Chlorhexidine (Low-Level Disinfection)
A 0.55% OPA is an alkylating agent, which was approved in
1999 by the FDA as a high-level disinfectant at room tempera- A 0.045% chlorhexidine acetoacetate is commonly used in vet-
ture with an immersion time of 12 minutes. It has superior erinary practice as a disinfectant for flexible endoscopes. It has
mycobactericidal activity compared with glutaraldehyde, with a few advantages but many disadvantages. Many veterinary
less contact time required. Other advantages include excellent clinics stock the concentrate (Nolvasan 2% solution, Fort
stability over a wide pH range of 3 to 9 and no activation Dodge Animal Health, Overland Park, KS) for use as an envi-
requirement. Pentax, Fujinon, and Olympus list OPA as a prod- ronmental disinfectant. Skin and respiratory irritation are less
uct compatible with flexible endoscopes. of a concern with chlorhexidine solution than with high-level
OPA is a potential respiratory and dermal irritant. Direct disinfectants. Also, it is relatively less expensive.
contact with skin may cause temporary staining, and repeated Chlorhexidine is a low level disinfectant. Product labeling
contact with the skin may cause skin sensitization. Vapors reports that the 0.045% solution is not effective against Pseudo-
should also be avoided. OPA vapors have caused irritation to monas aeruginosa or gram-positive cocci.11 Also, it is not labeled
the respiratory tract and eyes.8,15 Because there has been limited for disinfecting medical devices. Its use in the reprocessing of
clinical use of this chemical, it would be prudent to handle it endoscopes may be considered off-label.10 There are no com-
with the same precautions as glutaraldehyde. OPA should be patibility studies with endoscopic equipment and Chlorohexi-
used in a well-ventilated area and in closed containers with dine is not listed as compatible by endoscope manufacturers.
tight fitting lids. If adequate ventilation is not provided by the Because chlorhexidine can cause irreversible eye damage, eye
existing air conditioning system, use in local exhaust hoods or protection should be worn. Those using the solution should
in portable ventilation devices that contain filter media that wear latex gloves, and wash the outside of the gloves before
absorb OPA from the air. When using OPA, always use gloves, removing them. Contact with skin or clothing should be
eye protection, and fluid resistant gowns.8,15,16 When using avoided, and hands should always be washed after use. Special
latex rubber gloves, double glove, and/or change gloves every ventilation procedures are not required for this product.11,15
12 to 15 minutes.8,16 Nitrile rubber gloves, butyl rubber gloves, For low-level disinfection, follow the Nolvasan label instruc-
and 100% copolymer gloves may be used.8,17 tions for disinfection of inanimate objects. Dilute the 2% chlor-
Small spills may be cleaned up with a damp sponge or absor- hexidine solution by placing 3 oz (6 tablespoons) in a gallon of
bent pad. Larger spills should be deactivated with 25 g of gly- warm water to make a 0.045% solution.11 Allow a minimum of
cine (free base) powder per gallon over 5 minutes. See the 10 minutes contact time with the endoscope, as described in the
MSDS for specific control measures. Triple rinse empty con-  Application of Germicide section. A thorough rinse with wa-
tainers with water before disposal. Spent solutions of OPA may ter and alcohol should follow. Low-level disinfection and the
be disposed of down the drain unless prohibited by state and use of 0.045% chlorhexidine solution are not recommended for
local regulations.8,15 the routine reprocessing of flexible endoscopes.
Peracetic Acid/Hydrogen Peroxide Germicide Concentration Testing
A 0.08% peracetic acid/1% hydrogen peroxide solution (Cidex To achieve high-level disinfection, liquid chemical germicides
PA) is an oxidizing agent that has been approved by the FDA as should be maintained higher than their minimum effective con-
a high-level disinfectant at room temperature at an immersion centration (MEC). With repetitive use of the same solution, the
time of 25 minutes. Data from Advanced Sterilization Products concentration of the disinfectant may decrease because of dilu-
(the manufacturer of Cidex PA) states that compatibility testing tion. For example, the reuse of the same glutaraldehyde solu-
with Olympus and Pentax found that the solution had no del- tion for 20 endoscopy procedures reduces the concentration of
MAINTENANCE OF GASTROINTESTINAL ENDOSCOPES 259
2% to 1% glutaraldehyde. Test strips are available for determin- flexible endoscopes.4,5 Next, remove all channel adaptors. Dry
ing the concentration of each product. Ensure that concentra- the exterior of the endoscope with a soft, clean, lint-free towel
tions remain higher than the MEC by testing each day that a or gauze square. Thoroughly rinse, and dry all removable parts.
solution is reused. Disinfectant solutions must be discarded Do not reattach removable parts.7
whenever the concentration is less than the MEC or the use life
expires, whichever comes first.2,7 Storage
Endoscopes should be stored in a manner to promote drying
Application of Germicide
and prevent damage. Ideal storage racks suspend them from the
Completely immerse the endoscope and all removable parts in control section, with the insertion tube and umbilical cable
a basin of disinfectant. The basin must be of adequate size to hanging freely.1 Endoscope racks that hold the umbilical cable
accommodate the endoscope without undue coiling and must upright should not be used because they allow moisture to pool
have a tight fitting lid to contain the vapors of the disinfectant. at the depended part of the tube, leading to bacterial and fungal
To prevent damage to the endoscope, do not soak any sharp growth. They are often stored in cabinets to provide protection
instruments with it. Inject disinfectant into all channels of the from physical impact. Cabinets should be well ventilated to
endoscope until it can be seen exiting the opposite end of each avoid moisture buildup and be constructed of materials that are
channel. Take care that the channels are filled with high disin- easily cleaned. Do not attach removable parts to the endoscope
fectant and that no air pockets remain within the channels. during storage. The storage of endoscopes without the remov-
Cover the soaking basin with a tight fitting lid to minimize able parts facilitates continued drying of the channel and chan-
chemical vapor exposure. Soak the endoscope in the disinfec- nel openings.7 Endoscopes should never be stored in foam-
tant for the time and temperature required to achieve high-level lined cases, which prevent adequate ventilation and hold the
disinfection. Use a timer to verify soaking time. Flush all chan- scope in a coiled position. Also, the case lining is impossible to
nels completely with air before removing the endoscope from clean should it become contaminated. Cases should be used for
the high-level disinfectant. Purging the high-level disinfectant transportation and shipping only.4,5
from the channels preserves the concentration and volume of
high-level disinfectant, and prevents exposure from dripping Automated Reprocessors
and spilling.7,8
Automated reprocessors are available for high-level disinfec-
tion of flexible endoscopes. These machines may reduce the
Water Rinse
exposure of personnel to toxic chemicals and may standardize
All disinfectants used to reprocess flexible endoscopes have the the contact time of disinfectants.2,4,5,8 However, studies have
potential to injure mucous membranes if not thoroughly rinsed shown that automated reprocessors work no better than man-
from the endoscope.7 Chemical colitis caused by 3% hydrogen ual cleaning by trained staff.7 It is necessary to follow all steps
peroxide and glutaraldehyde has been reported in humans. for the mechanical cleaning of the endoscope before using an
After disinfection, the endoscope must be rinsed and the chan- automated reprocessor. Also, a final alcohol rinse is not in-
nels flushed with copious amounts of water.4,5 Ordinary tap cluded in the automated reprocessor. This step should be per-
water may contain microbes, including Pseudomonas spp and formed manually, followed by purging all channels with air.
Mycobacterium spp. In several reports, contaminated rinse wa- Drying and storage are the same as that with manual disinfec-
ter was the suspected source of P aeruginosa transmission to tion.4,5 Automated reprocessors are only used in institutions
patients through previously disinfected endoscopes.4,5 These with very high endoscopy caseloads and are financially infeasi-
bacteria, as well as fungi, can grow in the moist environment ble in most veterinary practices.
within a drying endoscope. Rinsing should be performed with
sterile water or filtered water. Alternatively, a tap water rinse Reprocessing Detachable Parts
may be followed by rinsing channels with 70% alcohol.4,5,7,18
Detachable parts, such as buttons, should be brushed to ensure
the complete removal of all organic debris. Cleaning brushes
70% Alcohol Rinse
should be disposable or thoroughly cleaned by receiving high-
Flush all channels, including accessory channels, with alcohol level disinfection.2,4,5 Water bottles and tubes used for endo-
until the alcohol can be seen exiting the opposite end of each scopic irrigation are difficult to clean and disinfect, and are
channel. A 70% isopropyl alcohol is used as a solvent to assist in often colonized by Pseudomonas spp. Therefore, only sterile
drying the interior channel surfaces. Alcohol mixes with the water should be used to fill the bottles.4,5
remaining water on the channel surfaces and acts to encourage
evaporation of the residual water, as air flows through the Reprocessing Biopsy Forceps and Other Instruments
channel. Use fresh alcohol that has been properly stored in a
Sterilization of biopsy forceps is arguably one of the most im-
closed container between uses. Alcohol, when exposed to air,
portant parts of the entire endoscopic reprocessing process
rapidly evaporates and, if below the recommended percentage
because it is the biopsy forceps that actually penetrate the pa-
level, cannot be relied on to assist in the drying process. Alcohol
tient s mucosa.2,10 Spiral wound instruments, such as biopsy
purges should be used even when sterile water is used for
forceps, are extremely difficult to clean, and sterilization at-
rinsing.1,2,7
tempts may fail if organic debris is not removed. Cleaning with
an ultrasonic cleaner and enzymatic solution can be helpful.2,4,5
Drying
These instruments are heat stable and, therefore, can undergo
Force air through the channels after rinsing. Avoid excessively steam sterilization.4,5 The importance of proper cleaning of the
high air pressure because it can damage the internal channels of biopsy forceps is reinforced by a reported outbreak of Salmo-
260 SHUMWAY AND BROUSSARD
nella newport that infected 8 human patients linked to contam- cessing of endoscopes are necessary to maintain a consistent
inated biopsy forceps.3 standard of care.16,19
Instruments such as rat tooth graspers, loops, and baskets are
used in the removal of foreign bodies. Although these instru-
References
ments do not penetrate the mucosa, cleaning should be thor-
1. Riel D: Endoscopy: Technical Issues. Davis, CA, UC Davis, Veterinary
ough. Using a clean brush ensures that all organic debris have
Medical Teaching Hospital, Small Animal Internal Medicine, 1998
been removed. Use an ultrasonic cleaner and enzymatic clean-
ing solution. High-level disinfection should be performed.2,4,5 2. Queensland Health: Endoscope Reprocessing. Brisbane, Queens-
land, Australia. Accessed October 1, 2003. Available from: URL:
http://www.health.qld.gov.au/endoscopereprocessing
3. Kaczmarek RG, Moore RM, McCrohan J, et al: Multi-state investiga-
Microbial Monitoring
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care facilities. Am J Med 92:257-261, 1992
Microbial monitoring of endoscopes is the only direct method
4. Alvarado CJ, Reichelderfer M: APIC guidelines for infection preven-
for ensuring that reprocessing procedures are adequate and
tion and control in flexile endoscopy. Am J Infect Control 28:138-
reliable.4,5 The best method to obtain a culture is to brush the
155, 2000
suction and biopsy channel with a sterile brush. This will re-
5. Martin MA, Reichelderfer M: APIC guidelines for infection prevention
lease organisms attached to the inner lumen of the channel. The and control in flexible endoscopy. Am J Infect Control 2:19-38, 1994
6. Olympus America, Inc: Olympus America, Inc. Product Information.
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Melville, NY, Olympus America, Inc, 2003
media. No growth should be seen on the cultures.4,5 Aerobic
7. Society of Gastrointestinal Nurses and Associates, Inc: Standards of
cultures should be attained on a regular schedule.
infection control in reprocessing of flexible gastrointestinal endo-
scopes. Chicago, IL. Accessed October 1, 2003. Available from:
URL: http://www.sgna.org/resources/guideline3.cfm
Record Keeping
8. Society of Gastrointestinal Nurses and Associates, Inc: Guideline for
the use of high-level disinfection and sterilants for reprocessing of
It is helpful to keep a log for each endoscope used in the
flexible gastrointestinal endoscopes. Chicago, IL. Accessed October
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1, 2003. Available from: URL: http://www.sgna.org/resources/
culture results, cleaning protocols, endoscope operation man-
guideline6.cfm
ual, and information on repairs. A section should also be dedi-
9. Chu NS, McAlister D, Antaonoplos PA: Natural bioburden levels
cated to procedures. In this section, a summary of each proce- detected on flexible gastrointestinal endoscopes after clinical use
and manual cleaning. Gastrointestinal Endosc 48:137-142, 1998
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This binder makes it possible for all information on each endo-
Gastrointest Endosc 49:836-841, 1999
scope to be easily accessible.
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Overland Park, KS, Fort Dodge Animal Health, 2003
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CA, Johnson and Johnson, 2003
Conclusion
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Flexible gastrointestinal endoscopy is a valuable diagnostic and ronment. Gastroenterol Nurs 18:142-145, 1995
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therapeutic tool for the care of patients with gastrointestinal
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disorders.1 When properly maintained, the endoscope is a valu-
26, 1994
able addition to the small animal practice. Maintenance in-
15. Johnson and Johnson: Cidex OPA (MSDS) Product Information.
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Irvine, CA, Johnson and Johnson, 2003
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Mistakes are common in the reprocessing of endoscopes and
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2003. Available from: URL: http://www.kemmed.com/rtkinfo.htm
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MAINTENANCE OF GASTROINTESTINAL ENDOSCOPES 261