Practical Gastrointestinal Endoscopy

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CHAPTER 6
steering causes the tip to slip past the angle to point straight at
the lumen of the descending colon.
5–Try shaft twist in case the configuration allows corkscrewing
force to be applied to the tip. Clockwise shaft torque tends to be
particularly effective at this point because most sigmoid colons
loop in a clockwise spiral—passing anteriorly out of the pelvis,
over the pelvic brim and curving laterally and posteriorly into
the descending colon (see Fig. 6.35). ‘Pull back-with-clockwise
twist’ is the trick to try. With luck it will simultaneously shorten
(pleat/accordion) the sigmoid over the scope shaft and move the
tip forward towards the fixed descending colon. When it works
the result is a most satisfying feeling for the endoscopist of ‘getting
something for nothing’, quite apart from avoiding pain for
the patient.
6– Changing the patient to the right lateral position can improve visualization
of the sigmoid–descending junction (air rises, water
falls) and may sometimes also cause the distal descending colon
to drop down into a more favorable configuration for passage. In
left lateral position the sigmoid will tend to be crumpled down
toward the left flank, with fluid also pooling there. Lying the
patient supine may improve the view and (especially in long and
mobile sigmoids) the gravitational effect of right lateral position
often improves things further still.
7–Use of force to ‘push through’ the loop should once again be the
option of last resort. It may be better to warn the patient and push
in calculatedly than to struggle on indefinitely or to abandon
the procedure when clinical indications for it are strong. Having
warned the patient to expect discomfort, a few seconds of careful
‘persuasive pressure’ may slide the instrument tip successfully
around the bend and then allow straightening again. Providing
the tip is pointing correctly, it should slip gradually over the
mucosa with the ‘slide by’ appearance of the mucosal vascular
pattern traversing the field of view. Continue to push if ‘slide
by’ continues smoothly; stop if the mucosa blanches (indicating
excessive local pressure) or if the patient experiences pain (indicating
undue strain on the bowel or mesentery). It should not
be necessary to push strongly and uncomfortably like this for
more than 20–30 seconds at the most; the instrument can then be
straightened back rapidly, taking the strain off the colon and its
attachments and making the patient comfortable.
In some patients, by good fortune, a spiral ‘alpha loop’ may
have been formed during insertion, which results in easy passage
(see pp. 125, 130–1); in other patients with long colons ‘push
through’ reaches up the descending colon anyway, and the endoscopist
may be quite unsure as to what has happened. Providing
that the patient does not experience pain the exact loop does not
matter, so long as the loop (whichever it is) is then removed.