Practical Gastrointestinal Endoscopy

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CHAPTER 6
lar disease. The pediatric instrument bending section is more
flexible, making it easier to obtain a retroverted view of some
awkwardly placed polyps, whether in the distal or transverse
colon, in order to ensure complete removal. Floppy pediatric instruments
are also particularly comfortable and easy to insert to
the splenic flexure, tending to conform to the loops of the colon
and to form a spontaneous ‘alpha’ loop, which avoids difficulty
in passing to the descending colon. The smaller diameter of the
shaft is, however, less easy to torque or twist and is more easily
damaged if used routinely for more extensive examination. For
limited adult examinations, as for strictures or diverticular disease,
a pediatric gastroscope can also be used (and has the bonus
of an even shorter bending section, but the disadvantage of limited
downward angling capability). Its very stiff shaft makes it
less suitable for total colonoscopy in small children and babies
than the pediatric colonoscope.
Accessories
All the usual accessories are used down the colonoscope, including
biopsy forceps, snares, retrieval forceps or baskets, sclerotherapy
needles, cytology brushes, washing catheters, dilating
balloons, etc. Long- and intermediate-length accessories work
equally well down shorter instruments, so it is sensible to order
all accessories to suit the longest instrument in routine use. Other
manufacturers’ accessories also work down any particular instrument
and, since some are better than others, it is worth taking
advice when buying replacements. A rarely seen specialized
accessory for colonoscopy is the stiffening tube, splinting device
or split overtube, the use of which is described later (p. 143).
Although not used by many endoscopists, and potentially hazardous
if wrongly used, it is still very occasionally invaluable
in avoiding recurrent loop formation of the sigmoid colon, for
exchange of instruments or for retrieving multiple polyps.
Carbon dioxide
Few colonoscopists, regrettably, use CO 2
insufflation, although
its use has much to commend it from the patient’s point of view.
CO 2
was originally used instead of air because of the explosive
potential of colonic gases during electrosurgery. However, with
the exception of bowel preparation using mannitol, the prepared
colon has been shown to have no residual explosive gas. Nonetheless,
even for routine examinations, the use of CO 2
offers the
striking advantage that it is cleared from the colon 100 times faster
than air (through the circulation, to the lungs and then breathed
out). This means that 15–20·minutes after CO 2
insufflation the
colon and small intestine are free of any gas, whereas air distension
can remain and cause abdominal bloating and discomfort for