A couple of helpful tips with common problems with flexible endoscopes: flickering video display and expanded bending rubber.

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Helpful Hints

2. Things you can do about…
• Bulging Bending Rubber
• Intermittent Video Problems

3. The case of the Bulging Bending Rubber
• What is it?
• How bad is it?
• How did that happen?
• What to do?

4. Bulging Bending Rubber
What is it?
• Air trapped in the endoscope following leak testing expands with
heat or reduced external pressure
• If bending rubber is left inflated over an extended period of time (e.g.
in storage cabinet) it will be permanently stretched
• Repeated over pressurizing the scope will prematurely stretch the
bending rubber
• Worn, aged bending rubber ( with time, use, heat, chemical) will also
lose its elasticity

5. Bulging Bending Rubber
How bad is it?
• Corrected early enough, there is little permanent damage to the scope.
Even if a new bending rubber needs to be replaced, it’s an inexpensive
repair
• Depending on how much stretching has occurred, the scope may become
difficult to introduce, to angulate or to manipulate in the patient
• Left unaddressed, the bending rubber can burst unexpectedly, e.g. during
shipping by air where there are large pressure changes, or during
reprocessing.
• A failed bending rubber during reprocessing, especially automated
reprocessing, can be catastrophic, often requiring the scope to be
overhauled, a very expensive repair.

6. Bulging Bending Rubber
How does it happen?
• Air trapped in scope following leak testing: the ETO connector was
removed quickly while the air pump is still on. Correct disconnect procedure was not
followed in leak testing.
• Scope shipped without ETO CAP installed: the same pressure
changes that cause lotion and tooth paste to ooze out of their containers in flight,
cause the bending rubber to expand. Bending rubbers have been seen to completely
rupture from air shipment.
• Over pressurizing the scope: it’s easy to over-pressurize a scope using a
manual leak tester. Even when the pressure needle is stopped by a stopper on the
dial, continued pumping will continue to increase the scope pressure, even though
the needle will not move.
• Overdue preventative maintenance: if the bending rubber looks worn, not
conforming snuggly to the bending section, or buckles significant under angulation,
have it replaced.

7. Air trapped in scope following leak testing
What to do…
• Review instructions on the tag attached to
the Leak Tester. Specifically the
disconnect procedure as reproduced
below…
“ After test, unplug the connector from light
source (or MU-1) and wait for about 30 seconds
to allow air to escape from inside the scope.
Then detach the cap from the scope”
• If a manual tester is being used, release air
from scope BEFORE disconnecting the tester
from the scope
• Double check that bending rubber is not
inflated before placing scope in strorage.
• Alsways install ETO cap prior to shipping

8. • Install ETO cap before shipping
Shipping & Manual Leak Testing
What to do…
• Visual inspection: Inspect the scope
regularly looking for discoloration of the
bending rubber, flaking, damaged or missing
adhesive band, exposed thread, missing set
screw at the distal tip, stretched bending
rubber, etc. Early service of the bending
rubber with any of these signs of wear and tear
will go a long way toward reducing repair costs.
• Do not over pressurize the scope during leak testing. The scope should be
pressurized to anywhere between 140mmHg minimum and 200mmHg maximum. Depending
on the size of the scope this should require squeezing the bulb no more than 2 or 3 times. For
large body scopes, it will require a little more pumping. The bending rubber will inflate but
should not balloon.

9. Intermittent Video Problems
• Most annoying problem with endoscope because:
– It is not always reproducible
– The problem may have many different symptoms such as flickering, momentary
screen freeze, disintegrating image, green screen, flickers when scope is
angulated, etc.
– It has many possible causes
– A misdiagnosis, i.e. CCD problem, can translate to an very expensive and
unnecessary CCD replacement
• The check list in this article helps to reduce (hopefully eliminate)
unnecessary trips back and forth to the repair facility
• The more information provided to the repair technician by the user will help
speed the diagnosis process

10. Intermittent Video Problems
Possible Causes
• Poor electrical contacts:
– Bent, missing pins (in pigtail, scope, light source)
– Corroded dirty contacts (light source, processor)
– Bad pigtail
– Loose feedback cable (on pigtail)
• Cable harness in scope damaged (image flickers or freezes when scope is angulated
or coiled)
• Moist or wet electrical contacts
• Loose or poor grounding
• Internal minor fluid invasion
• Thermal problems (video problem becomes more consistent as scope warms up in
use)
• Damaged CCD

11. Intermittent Video Problems
Check List
Visual Inspection of connectors (light guide connector, both ends of
pig tail cable, light source connector, and processor connector)
Sign of corrosion
Moisture on connectors
Bent, missing or otherwise damaged pins
Dirty connectors
If possible, confirm that intermittent video problem does not occur
with another scope (used in the same setup)
Confirm that intermittent video problem does not occur with another
pigtail cable
Note if problem becomes more consistent the longer the scope is
in use (a thermal problem with the electronics)
Check for poor, or loose grounding (ask biomed engineer for help
with this)
Note if video problem occurs when scope is coiled or angulated

12. Intermittent Video Problems
Keeping Contacts Clean
A great number of intermittent video issues result
from dirty or corroded electrical contacts.
A contact cleaner spray is very effective at
keeping your connectors trouble free
(Caution: read manufacturer’s instructions
before use)
A cotton swab is useful in drying out wet contact
and clean up built up corrosion