Practical Gastrointestinal Endoscopy

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CHAPTER 7
into the end of the tube and the whole assembly removed together.
A large rigid proctoscope and tissue-grasping or spongeholding
forceps can be similarly used, pulling out the polyp and
instrument together.
Multiple polyp recovery
Ninety per cent of adenoma patients have only one or two polyps
and it is very uncommon to find more than five. Some multiple
polyps (hyperplastic, Peutz–Jeghers, juvenile, lymphoid,
lipomatous or inflammatory) are non-neoplastic, so that it may
sometimes be preferable to await results of standard biopsies
before undertaking heroic numbers of polypectomies, which
are probably more risky than the lesions themselves. In the rare
circumstance that a patient has six or more obvious adenomas,
it is essential to examine the whole colon before snaring, to be
certain that multiple other smaller polyps are not present (with
the possibility of a diagnosis offamilial adenomatous polyposis,
or FAP). Looking for tiny reflective nodules in the ‘light reflex’
off the transparent mucosal surface shows up polyps down to
1·mm in diameter that are invisible to direct vision. Melanosis
coli also shows up tiny non-pigmented polyps or lymphoid follicles
very well.
Dye spray (‘chromoscopy’) enhances the view of fine detail,
almost to dissecting microscope level. The principle is to use a
spray of surface dye (0.1–0.2% indigo carmine solution or 10%
dilution of non-permanent blue fountain-pen ink) (see p. 156),
which shows up any small polyps down to under 0.5 ·mm in size,
seen as pale islands on a blue background. Dye can be applied
using a dye-spray catheter, usually while withdrawing the scope.
An easier way is to use 5·mL of dye in an air-filled 20–30·mL syringe
inserted into the rubber biopsy valve of the scope, which
takes only a few seconds to dye a short segment of colon without
using a catheter. Silicone-emulsion anti-bubble solution can be
added to the dye to avoid small bubbles, which can look confusingly
like tiny polyps. Histology of any polyp seen is essential
for certainty because lymphoid follicles can resemble adenomas
to the untutored eye (although usually dimpled or ‘umbilicated’
at their centers).
Retrieval of multiple polyps for histology is a matter of compromise
in order to avoid needing to reinsert the colonoscope multiple
times. In practice retrieval can be facilitated by use of accessories
such as the multi-wire basket or polyp-retrieval net, which are
able to retrieve up to three to five moderately large polyps at a
time, whereas only one or two polyps can be picked up in the
polypectomy snare. Any smaller polyps are either destroyed by
hot biopsy or snared and then aspirated into a filtered polyp suction
trap or into a gauze placed in the suction line (see Fig. 7.27).
A ‘wash-out’ technique is a rarely needed compromise after