Practical Gastrointestinal Endoscopy

THERAPEUTIC UPPER ENDOSCOPY 65
Membrane
Stent
Guide wire
Fig. 5.6–Covered metal mesh stent.
Stent variety
Plastic stents have largely been replaced with expandable metal
mesh stents, since they are easier and less hazardous to insert.
Many types are now available. They vary by the type, diameter
and weave of the wires (which determine their expansile
strength), by their shapes and sizes, and by the presence or
absence of a covering membrane (Fig. 5.6). This membrane is
helpful in patients with fistulae, and reduces tumor ingrowth,
but some mesh must left exposed to prevent migration. Stents for
use in the esophagus have luminal diameters of 15–24·mm, and
lengths of 6–15·cm. They are compressed into delivery systems
of 6–11·mm. Most expand gradually over a few days, and become
fully incorporated in the esophageal wall so that they cannot be
removed. Less powerful stents—although easy to place and well
tolerated—may not expand sufficiently to relieve the patient’s
symptoms, even withballoon dilation.
Stent insertion
The patient is fully informed about the aims, the potential serious
risks of the procedure, and the (few) alternatives. Antibiotic
prophylaxis should be considered. The lesion is assessed carefully
by radiology and endoscopy, and bougie dilation is performed
if necessary (to about 12·mm), to allow passage of the
endoscope if possible. The upper and lower margins of the tumor
are marked by endoscopic injection of contrast medium, using
a sclerotherapy needle. A guidewire is placed, and its position
checked by fluoroscopy.
The stent system is then introduced over the guidewire and
the stent is released by gradual withdrawal of the sleeve. Correct
positioning of the stent is judged fluoroscopically (using the
contrast medium marks), and then by repeat endoscopy.