Practical Gastrointestinal Endoscopy

THERAPEUTIC COLONOSCOPY 199
wire, leaving the tube behind and withdrawing the guide wire.
Frequent irrigation of the tube is likely to be needed because of
its small diameter.
A ‘piggy-back’ method carries up a larger drainage tube alongside
the scope, a loop attached to the leading end of the tube being
grasped by forceps (Fig. 7.44). A variation avoids using the forceps
and allows better suction during the procedure (the colon
may be unprepared and foul); a thin loop of cotton thread at the
end of the tube is held by a loop of strong monofilament nylon
passed through the suction channel; once in the proximal colon
a sharp tug on the nylon loop breaks the cotton thread and the
tube is free. The drainage tube is attached to a suction pump or
drainage bag. The tendency of the deflation tube to be ejected by
colonic movement can be prevented by stiffening it with a guide
wire (Savary–Guillard or similar steel-wire type), silicone-lubricated
for insertion.
Volvulus and intussusception
The colonoscope can be used to deflate a sigmoid volvulus, effectively
acting as a steerable flatus tube, so that the deflated loop
can de-rotate passively. Large-channel colonoscopes allow a deflation
tube (as above) to be inserted through the instrumentation
channel. After the tube or endoscope tip is passed gently into
or through the twisted segment, deflation alone is usually sufficient
for the torsion to reverse spontaneously and endoscopic
manipulation is usually unnecessary. However, if the segment
appears blue-black and gangrenous from ischemia, surgery is
indicated because of the high risk of perforation.
Intussusception is easy to diagnose but usually impossible to
reduce colonoscopically, because not enough inward push can
be transmitted around the looped colon to the ileo-cecal area
(where this rare event most commonly occurs). Identifying and
removing any causative factor, such as a large polyp or lipoma,
should help prevent recurrence.
Angiodysplasia and hemangiomas
In treating angiodysplasia it is best to err on the side of applying too little
heat. Even minor whitening and edema will progress to produce
remarkable local ulceration within 24 hours. It is easy enough
to repeat the examination a few weeks later to check results,
but difficult to justify perforation from overaggression during
the first procedure. Since angiodysplasias occur mainly in the
thin-walled proximal colon, great care should be taken with
whichever modality is used—preferably APC (argon plasma
coagulation) for its ease, efficacy and relative safety; but, if this
is unavailable, any other form of electrocoagulation (mono- or
bipolar), heater probe or laser, can be carefully applied. The
Fig. 7.44 A deflation tubecan be
carried up alongside the colonoscope.