Practical Gastrointestinal Endoscopy

COLONOSCOPY AND FLEXIBLE SIGMOIDOSCOPY 133
sigmoid appears not to be straightening. Very occasionally looping
may be so complex that de-rotational twist has to be first one
way, then the other.
Instrument shaft loops external to the patient
Rotating the colonoscope to straighten loops may result in shaft
loops external to the patient. Because of the negative effect of any
loops on instrument handling, especially on torque steering, it is
good practice to de-rotate the control body to transfer this loop
to the umbilical (see Fig. 6.33). Several (up to three) loops can be
accommodated in the umbilical without harm, but sometimes it
may be necessary to unplug the instrument from the light source
and unravel the umbilical. The alternative for the dexterous endoscopist,
and if the instrument is straight, is to de-rotate the
external shaft loop while steering the tip into the lumen so that
the colonoscope rotates on its axis within the colon; however, if
the shaft is not straight the instrument tends to slip back in the
process.
Diverticular disease
In severe diverticular disease there may be a narrowed lumen,
pericolic adhesions and problems in choosing the correct direction
(Fig. 6.50a). However, once the instrument has been
laboriously fiddled through the area, the ‘splinting’ effect of the
abnormally rigid sigmoid may facilitate the rest of the examination.
In the presence of diverticular disease the secret is extreme
patience, with care in visualization and steering, combined with
greater than usual use of withdrawal, rotatory or corkscrewing
movements. It helps to realize that a close-up view of a diverticulum
means that the tip must be deflected to a right-angle
(by withdrawal and angulation or twist) to find the lumen (Fig.
6.50b). Using a thinner and more flexible pediatric colonoscope
or gastroscope may make an apparently impassable narrow,
fixed or angulated sigmoid colon relatively easy to examine—
which sometimes also saves the patient from surgery. Having
successfully passed severe or angulated sigmoid diverticular
disease (especially if it has taken a short scope to do so), it is the
endoscopist’s worst nightmare if the proximal colon then proves
to be long and mobile.
‘Underwater colonoscopy’ may help passage in some patients
with very hypertrophic musculature and redundant mucosal
folds in diverticular disease, in whom it can be very difficult to
obtain an adequate view. Water can distend a narrow segment
better than air, water having the combined advantages of being
non- compressible, remaining in the dependent sigmoid colon
(rather than the tendency of air to rise and distend only the