Practical Gastrointestinal Endoscopy

COLONOSCOPY AND FLEXIBLE SIGMOIDOSCOPY 163
differential diagnosis of the various specific and non-specific
inflammatory disorders may not be easy: infective conditions,
ulcerative, ischemic, irradiation and Crohn’s colitis can look
amazingly similar in the acute stage, although biopsies will
usually differentiate between them. The ulcer from a previous
rectal biopsy or a solitary ulcer of the rectum can look endoscopically
identical to a Crohn’s ulcer, whereas tuberculous ulcers are
similar but more heaped up, and amebic ulcers are more friable.
Ulceration can also occur in chronic ulcerative colitis and
ischemic disease but against a background of inflamed mucosa.
The endoscopic appearances must be taken together with the
clinical context and histological opinion. In the severe or chronic
stage it is often impossible for either endoscopist or pathologist
to be categoric in differential diagnosis.
Unexplained rectal bleeding, anemia or occult
blood loss
Blood loss or anemia is a common reason for undertaking
colonoscopy. Although colonoscopy gives an impressive yield
of radiologically missed cancers and polyps, 50–60% of patients
will show no obvious abnormality, which raises the specter of
whether anything has been missed.
Hemorrhoids can be seen with the colonoscope (by retroversion
in the rectum if necessary), but a proctoscope should be used for
a proper view and the endoscope tip can be inserted within it to
show the patient or take video-prints at ‘video-proctoscopy’.
Hemangiomas are rare, but they can assume any appearance
from massive and obvious submucosal discoloration with huge
serpentine vessels to telangiectases or minute solitary nevi,
which could easily be missed in folds or bends.
Angiodysplasias are rare and mainly occur in the cecum or ascending
colon, but also in the small intestine. They have variable
appearances, may be solitary or multiple (often two or three) and
are always bright red, but they can be small vascular plaques,
spidery telangiectases or even a 1–2·mm dot lesion.
Pain and ‘pain mapping’
Irritable bowel symptoms are probably the commonest single
reason for referral. Functional bowel disturbance in an otherwise
normal colon can take many forms, and ‘spastic colon’ pain
may present with equally variable referred-pain radiation patterns—to
the right or left loin, back or even into the thighs. An
occasionally useful and very simple colonoscopic procedure is to
map the pain experienced during distension at different sites in
the colon produced by inflating a small balloon taped alongside
the tip of the colonoscope (Fig. 6.96). A child’s balloon, finger-cot
or the cut-off finger of a rubber glove is bound with fine thread