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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1348_Библиотеки_им_академика_М_И_Перельмана.pdf
Enteric Stents: Indications
and Placement Techniques
Todd Baron
1 1
Self-expandable metal biliary stents (SEMS),
fi rst used outside of the USA, became commercially available in the USA approximately
20 years ago because of their prolonged patency
when compared to plastic biliary stents [ 1 ] .
Esophageal SEMS were introduced soon after
expandable biliary stents, and SEMS speci fi cally
designed for gastroduodenal use were developed
several years later. However, both esophageal
and biliary SEMS have been used for relief of
gastroduodenal obstruction. The indications and
placement techniques for enteric stents, de fi ned
as gastric and small bowel stents for the purposes
of this chapter, will be reviewed.
Basic Concepts
Self-expandable stents placed for enteric use are
composed of a variety of materials ranging from
plastic to stainless steel to nitinol. Stents vary
based upon type of material that they are composed
of, lattice width (if any), con fi guration, length
and diameter, and presence and degree of covering.
More importantly, in order for precise placement
to be achieved, the degree of shortening (if any)
that occurs with expansion and the nuances of the
delivery and release systems must be known.
There are a number of stents available from a
T. Baron , M.D. ()
Department of Medicine , Mayo Clinic ,
200 First Street SW , Rochester , MN 55905 , USA
e-mail: baron.todd@mayo.edu
variety of manufacturers around the world. The
principles of all expandable stents are similar, and
the concepts presented here can be applied to all
expandable stents.
It is extremely helpful to have nursing
assistants who are comfortable with complex
therapeutic endoscopic procedures to include
expandable stent placement. Moreover, an understanding of the complexities of stent placement
will assure that complications are minimized [ 2 ] .
Indications for and Contraindications
to Enteric Stent Placement
Indications
There are several indications for placement of
enteric stents (Table
into benign and malignant conditions, although
indications for placement in malignant disease
are much more common than for benign disease.
In Table
tion and type of disease process. Indications for
enteric stent placement in benign diseases are
generally due to postoperative complications that
include strictures, leaks, and fi stula. Post-bariatric
surgery, historically Roux-en-Y gastric bypass,
and more recently, sleeve gastrectomy can be
associated with postoperative leaks, fi stula, and
strictures and can be managed using temporary
stent placement [ 3– 11 ] (Fig. 11.1 ). Similarly,
occasional patients who have had prior Billroth II
operations and pancreaticoduodenectomy may
11.1 , indications are divided into loca-
11.1 ). These can be divided
R. Kozarek et al. (eds.), Self-Expandable Stents in the Gastrointestinal Tract,
DOI 10.1007/978-1-4614-3746-8_11, © Springer Science+Business Media New York 2013
159
160
T. Baron
Table 11.1 Indications for placement of enteric stents
Benign
Gastric
Postoperative fi stula/leaks – gastric (sleeve gastrectomy) and gastrojejunal anastomosis (Roux-en-Y
gastric bypass, post-Whipple and Billroth II)
Gastric stricture (sleeve gastrectomy)
Duodenal – stricture due to peptic ulcer disease;
duodenal fi stula (rare)
Small bowel – postoperative strictures – anastomotic,
Crohn’s disease (rare)
Malignant
Gastric obstruction
Primary and recurrent gastric cancer
Gastrojejunal anastomosis (afferent and efferent limb
obstruction)
Gastric stricture (sleeve gastrectomy)
Duodenal obstruction
Periampullary cancer
Pancreatic cancer/metastatic disease to the head of
the pancreas
Cholangiocarcinoma
Gallbladder cancer
Locally invasive tumors (colon cancer)
Small bowel – metastatic disease (particularly ligament
of Treitz), distal terminal ileum (pelvic cancers,
metastatic disease)
Other (uncommon)
Perforation of the duodenum or jejunal limbs of
anastomoses (within reach of endoscope and stent
delivery system)
Bridge to surgery
Transgastric or transduodenal placement for drainage
or debridement of pancreatic necrosis
develop benign anastomotic complications that
can be managed with stents [
12 ] . Crohn’s disease
with small bowel stricture is an uncommon indication for stent placement, although recent data
on the use of SEMS [ 13 ] , as well biodegradable
stents [
14 ] , show promise for these patients. In
most patients with benign strictures, stent placement should only be considered after the patient
has failed an adequate trial of serial endoscopic
dilation.
Malignant disease is a much more common
cause of luminal obstruction and needs palliative
enteric stent placement. Rarely, enteric stents are
placed as a bridge to surgery (e.g., primary small
bowel lymphoma), although there are no published
data for this indication.
Fig. 11.1 Use of a fully covered stent for treatment of
complete gastric outlet obstruction due to a benign stricture
following sleeve gastrectomy. ( a ) Endoscope is positioned
above the predeployed stent. ( b ) Postdeployment upper
gastrointestinal series shows persistent narrowing. The
stent was removed 3 months later, and the patient remains
well 5 years later
Before offering stent placement for relief of
gastric outlet obstruction (GOO), the degree of
oral intake should be assessed. A gastric outlet
obstruction scoring system (GOOSS), adapted
from the dysphagia scoring system, was introduced by Adler and Baron in 2002 [ 15 ] and has
become accepted as a measure of oral intake
(Table 11.2 ). Patients with GOOSS scores <2 are
candidates for stent placement. Alternatively,
16111 Enteric Stents: Indications and Placement Techniques
palliative gastrojejunostomy, increasingly
performed laparoscopically, should be considered
an alternative to stent placement in patients with
anticipated survival longer than 3–4 months [
16, 17 ] ,
potentially predictable by a WHO (World Health
Organization) score. The WHO score is based
upon a scale of 0–5, with 0 being healthy and 5
being dead. A recent study showed that patients
Table 11.2 Gastric outlet obstruction scoring system
(GOOSS)
Level of oral intake Score
No oral intake 0
Liquids only 1
Soft solids 2
Low-residue or full diet 3
with a WHO score of 0–1 may be managed with
gastrojejunostomy, while those with a WHO
score of 3–4 should be considered for stent placement [ 18 ] as a consequence of the longer survival
and more durable duration of palliation in the
surgical group. The type of malignancy that
causes lumen obstruction (Table 11.1 ) varies
throughout the world. For example, in the East,
primary and recurrent gastric cancer with resultant
GOO is more common, whereas in the West, pancreatic cancer is the most common cause of GOO.
Occasional patients have distal small bowel
obstruction that does not involve the colon, but
only be reached retrograde via colonoscopy
(Fig. 11.2 ). Free luminal perforation, usually iat-
rogenic, is a rare indication for enteric stent
placement [ 19 ] (Fig. 11.3 ).
Fig. 11.2 Placement of fully covered biliary stent for
treatment of a benign postoperative distal ileal anastomotic
stricture. ( a ) Colonoscope has been passed through the
ileocecal valve to the site of obstruction. Injected contrast
does not pass the obstruction. ( b ) After traversing the
stricture with a guidewire, the upstream dilated ileum is
seen. ( c ) Note placement of a fully covered biliary stent
and 10-Fr nasojejunal tube inserted for safety and
decompression. The stent passed spontaneously 1 month
after resolution of obstruction
162
T. Baron
Fig. 11.3 Closure of a large lateral wall duodenal perforation during ERCP for obstructive jaundice. ( a ) The
duodenoscope has been removed and a Savary wire
advanced beyond the ligament of Treitz using a forward-
Contraindications
There are relatively few contraindications to placing self-expandable, enteric metal stents. Free perforation, although considered a contraindication to
most endoscopic procedures, may, in fact, be an
indication for perforation closure (Fig.
Peritoneal carcinomatosis is a relative contraindication to enteric stent placement because
many patients have multifocal areas of obstruction and encasement of the small bowel and may
not respond to stent placement for palliation of
obstruction; moreover, if clinically successful,
the improvement is often short-lived. Patients
with peritoneal carcinomatosis are identi fi ed by
the presence of underlying malignant ascites
11.3 ).
viewing endoscope. Free air outlines the kidney (K).
( b ) Immediately after placement of a covered non-TTS
esophageal stent. ( c ) Upper GI 2 days later shows no
leak
and/or peritoneal thickening on abdominal CT
imaging. There are two morphologic types of
peritoneal implants. Layered implants (higher
grade, nonmucinous, and invasive lesions) conform
to the normal shape of abdominal structures and
are not well seen on computed tomography (CT),
whereas nodular implants (lower grade, mucinous, and noninvasive lesions) are more readily
apparent (Fig.
11.4a ) [ 20 ] . In one recent study,
patients with peritoneal carcinomatosis were
found to have similar results to those without
[ 21 ] . This is in contrast to this author’s experience, although I believe that selected patients
with peritoneal carcinomatosis and what appears
to be a single, dominant obstructive stricture
with marked upstream dilation and a clear-cut
16311 Enteric Stents: Indications and Placement Techniques
Fig. 11.4 Peritoneal carcinomatosis in the setting of
SEMS placement. ( a ) CT shows typical features with
ascites and nodularity around the liver ( single arrow ) and
nodules in the left upper quadrant adjacent to the colon
( double arrows ). Ascites (marked by A) is present
transition point on CT may respond to stent
therapy (Fig. 11.4b ). In such cases, where stent
placement is technically successful, yet clinically
unsuccessful, placement of additional stents is
usually futile and other means of palliation should
be undertaken (such as nasogastric or decompressive gastrostomy tube placement).
Stent Selection
Selection of the appropriate stent is based upon
the indication for placement and stent availability. For documented, unresectable disease, uncovered stents are most commonly used because of
their low rate of migration compared to covered
stents, although the latter are associated with a
decrease in tumor ingrowth [
for enteric use are available outside of the USA.
In the USA, the only available, dedicated enteric
stents are uncovered [ 23 ] . The advantage of these
dedicated stents is that their delivery systems are
long enough and small enough in diameter to
pass through the scope (TTS), including adult
colonoscopes. The lack of removability, however,
makes them unsuitable for treatment of benign
disease or closure of fi stula. Thus, within the
USA, stent options for benign disease and for
22 ] . Covered stents
throughout. ( b ) Upper gastrointestinal series in same
patient shows high-grade lesion. Despite successful stent
placement and patency con fi rmed by upper gastrointestinal series, the patient did not clinically improve, and distal
lesions were identi fi ed
closure of fi stula are limited to the use of esophageal and biliary stents.
Esophageal stents are available as fully and
partially covered self-expandable metal (SEMS)
or plastic (SEPS) but are limited by their short,
non-TTS delivery systems. The only available
SEPS (see Chap.
3 ) has a particularly rigid
delivery system that limits their use to placement in lesions that are close to the mouth and
are relatively straight in the projected pathway
(e.g., treatment of a Roux-en-Y gastrojejunal
anastomotic stricture or leak).
Esophageal SEMS are more fl exible, but their
relatively short delivery systems generally limit
transoral placement in patients with nonsurgically
altered anatomy to the fi rst and second portion of
the duodenum in best-case scenarios. However,
novel placement techniques include placement
through gastrostomy tracts – either after maturation [ 24 ] or through fresh tracts created with
introducer systems (Fig.
delivery systems [
25 ] , and use of overtubes [ 26 ] .
11.5 ), extension of
Biliary SEMS are available as partially and
fully covered stents and are long enough to pass
through a colonoscope and for benign strictures
of the small bowel, either antegrade or retrograde.
The disadvantage to these stents is a luminal
diameter of 8–10 mm. However, side-by-side
164
T. Baron
Fig. 11.5 Closure of a large duodenal fi stula (at site of
percutaneous pigtail drain) using overlapping covered
(partially and fully) esophageal stents. A gastrostomy
sheath ( small arrows ) was placed percutaneously immedi-
ately before stents were passed through the sheath. Note
small-caliber endoscope ( large arrow ) could also be passed
through sheath to assess stent position after deployment
placement is possible to achieve luminal diameters
of 20 mm (Fig. 11.6 ).
Gastroduodenal Stent Placement
Preparation, Sedation, and Positioning
Obtaining a pre-procedural radiographic contrast
study is not essential, and often not performed,
although such imaging allows determination of
the anatomy and stricture length (Figs.
11.6a ) and precludes need for passage of the
endoscope beyond the lesion to determine their
length and angulation. It is most helpful if it is
unclear whether the patient’s symptoms are due
to obstruction or other cancer-related processes
(neural invasion by tumor with delayed gastric
emptying, peritoneal carcinomatosis). Most
patients will have had a recent abdominal CT
scan which provides information on degree of
obstruction, location, length of stricture, and
presence or absence of fi stula.
Before undertaking stent placement in patients
with malignant gastroduodenal obstruction, it is
important to fi rst assess the status of the biliary
tree, since placement of an expandable stent
across the papilla may make subsequent endo-
11.4 and
scopic access to the papilla dif fi cult, if not
impossible. In addition, in patients with proximal
duodenal strictures, the stent does not necessarily
have to cross the papilla to achieve palliation.
Thus, a stent should be chosen that is adequate to
cross the lesion, but not excessively long so as to
prevent access to the papilla, if potentially
required in the future. A recent review of combined
gastroduodenal and biliary obstruction has been
published [ 27 ] , and a technical approach to
combined obstruction will be discussed later in
this chapter.
Not unexpectedly, patients with complete
gastric outlet obstruction have retained liquids
and/or solids and are at risk for aspiration during
stent placement unless precautions are taken.
Patients with complete obstruction are already nil
per os, hospitalized, and often have nasogastric
suction for decompression. Nonetheless, solid
food may not be adequately evacuated and remain
in place. Outpatients with subtotal obstruction
should consume clear liquids for at least 24 h
prior to their procedure, but may have retained
solid food. Sedation with airway protection
(endotracheal intubation), large-bore evacuation,
type of endoscope, and patient positioning all
play a role in the prevention of aspiration and
optimization of endoscopic visualization. Largebore evacuation tubes can be used, if necessary,
to allow endoscopic visualization, but are best
reserved for patients who have airway protection.
Large working channel (6 mm) endoscopes,
such as those designed for removal of blood
clots during gastrointestinal bleeding, can be
used to evacuate semisolid material.
Fluoroscopy, although not always necessary
when stents are placed using endoscopic techniques, especially for nonobstructive indications, should be readily available and is
mandatory when stents are placed using interventional radiologic techniques alone. Placing
the patient in the left lateral decubitus position
prevents aspiration, but the fl uoroscopic image
is less than ideal for gastroduodenal stent placement. Thus, placement in the prone or supine
position is preferred. When moderate or monitored anesthesia care is used, I place the patient
in the left lateral decubitus position and remove
all gastric contents, if possible. The patient is
16511 Enteric Stents: Indications and Placement Techniques
Fig. 11.6 Treatment of a benign duodenojejunal anastomotic stricture with side-by-side covered biliary stents.
( a ) Upper GI contrast series showing stricture. ( b ) Two
guidewires are passed alongside each other. The fi rst stent is
predeployed in position across the stricture. ( c ) Radiograph
subsequently placed supine and the airway
carefully monitored and suctioned with the head
of the bed elevated (if possible). In addition, one
may consider endotracheal intubation in these
patients to prevent aspiration.
taken immediately after deployment of both stents. Contrast
is injected through the inferior stent. ( d ) Endoscopic photo
of side-by-side covered expandable metal biliary stents.
( e ) Follow-up upper gastrointestinal series after removal of
both stents shows resolution of stricture
Choice of Endoscope
The choice of endoscope for gastroduodenal stent
placement depends on the site of the lesion (stomach versus duodenum), type of stent, and whether
166
T. Baron
an ERCP will be done at the same setting.
Small-caliber endoscopes (5.4-mm outer diameter or less) can be used for gastric lesions and
those with a disease process at or near a gastrojejunal anastomosis. These endoscopes allow easy
traversal of tight strictures for endoscopic inspection and may obviate fl uoroscopy to determine
stricture length. However, the working channel is
small, suction capability is suboptimal, and the
scopes do not permit passage of accessories
(catheters), and essentially, only guidewires can
be passed. However, once a guidewire is passed,
the endoscope can be removed, and a therapeutic
channel endoscope can be backloaded over the
wire for TTS delivery [
28 ] .
Standard adult endoscopes are intermediate
in terms of fl exibility and use of accessories, but
the working channel does not allow TTS stent
placement. Therapeutic channel endoscopes
(working channel ³ 3.8 mm) are most often used
when TTS stents with predeployment delivery
systems of 10 Fr are placed.
Duodenoscopes also allow passage of TTS
stents and are advantageous when ERCP with
biliary stent placement and gastroduodenal stents
are placed in the same session, precluding the
need to change endoscopes. The side-viewing
duodenoscope may be helpful in those patients in
whom the stricture cannot be traversed with a
forward endoscope and may allow an en face
view of the stricture.
Upper endoscopes and duodenoscopes are
usually limited to lesions proximal to the second
duodenum in patients with GOO since the often
dilated stomach creates looping that consumes the
length of the endoscope. Thus, even for proximal
duodenal lesions, it may be useful to use adult
caliber colonoscopes for TTS placement. These
scopes are essential for lesions beyond the
second to third duodenum, to include the proximal jejunum in patients with intact anatomy.
Moreover, they are often used for patients with
afferent limb obstructions far from the origin of
the anastomoses.
Finally, balloon enteroscopes may be useful in
selected cases, not only because of the ability to
pass deep into the bowel but also because of their
fl exibility. Following wire passage beyond the
stenosis, the endoscope can either be removed
and a therapeutic endoscope backloaded over the
wire, or the stent can be passed through the
overtube [
been used with spiral overtubes [
29 ] . Similar placement techniques have
30 ] .
Insertion Techniques
Stents can be placed using endoscopic techniques
with or without fl uoroscopy and can be TTS or
non-TTS. Alternatively, stents can be placed
using interventional radiologic techniques alone.
TTS and non-TTS endoscopic techniques will be
discussed separately, but the rate-limiting step
that is common to all techniques for successful
placement is passage of a guidewire across the
intended site of placement. This can be technically dif fi cult in patients whose primary problem
is obstruction, particularly complete obstruction.
Thus, techniques to traverse the lesion are especially important. This chapter will focus primarily
on endoscopic approaches.
Through-the-Scope Insertion
Since therapeutic channel endoscopes (working
channel ³ 3.8 mm) are needed to place TTS stents
and are large in caliber, it is frequently not
possible to traverse the stricture with the endoscope and is not necessary to achieve placement.
Thus, aggressive dilation of the stricture in order
to traverse it (unless a duodenoscope is needed to
pass through the stricture to reach the papilla)
should be avoided to minimize perforation risks.
Occasionally, however, small-caliber endoscopes
are useful to pass guidewires; however, the working
channel only accepts 0.035–038″ guidewires and
not standard diameter biliary catheters. This
requires removal of the endoscope and backloading of a therapeutic endoscope to place the
stent in TTS fashion [ 28 ] , although at times, a
second guidewire can be inserted through a therapeutic scope alongside the initial wire without
the need to backload the wire.
The usual approach is to pass the endoscope to
the site of the lesion. In the presence of subtotal
obstruction, water-soluble contrast can be injected
through the working channel of the endoscope to
de fi ne stricture characteristics and a fl exible
0.025–0.035″ long-length biliary wire passed
16711 Enteric Stents: Indications and Placement Techniques
through the stricture freehand or through a cathe-
ter. The stent is passed through the lesion and
deployed across the stricture. In complete obstruction or more dif fi cult, tortuous strictures, a biliary
occlusion (stone retrieval) balloon preloaded with
a hydrophilic wire is in fl ated to 18 mm with its tip
positioned against the lesion to provide pressure
for injection across the stricture in an attempt to
obtain a “strictureogram” (Fig.
11.7a ). If this is
unsuccessful, a biliary sphincterotome may be
useful (Fig. 11.7b ) when an en face view of the
stricture cannot be obtained since they can be
bowed to change direction and orientation, especially those that are rotatable. Once the stricture
has been traversed with the catheter, contrast is
injected to con fi rm bowel entry and to de fi ne the
stricture length (Fig. 11.7c ). The stent length can
be con fi rmed by in fl ating the occlusion balloon
once it is beyond the stricture. The in fl ated balloon
is pulled snugly against the distal end of the stricture. The catheter is grasped at the biopsy port, and
the balloon is de fl ated and withdrawn until it is
visible endoscopically on the proximal side of the
stricture. The distance between the operators’
fi ngers and the biopsy cap corresponds to the
length of the stricture.
A stent is chosen with a fi nal length after
deployment about 4 cm longer than the measured stricture. The stent is passed through the
channel of the endoscope and across the lesion.
Predeployment stent placement is rarely needed
because of the small diameter delivery systems.
It is important to note that most gastroduodenal stents foreshorten up to 40% during deployment and all deploy from the distal end. Thus, a
key to optimal stent placement is to position the
endoscope about three to four centimeters proximally from the proximal end of the stricture while
endoscopically monitoring the proximal end. The
stent will appear to move away from the tip of the
endoscope as it is pushed out of the delivery
system as it shortens during expansion; thus, the
endoscopist usually needs to pull back on the
delivery system during deployment. Most dedicated enteral stents are recapturable up to 70–80%
of complete deployment, and thus, if the process
is not progressing as planned, the stent can be
recaptured and redeployed after appropriate
adjustments are made.
After deployment of the stent, the delivery
system is withdrawn, but the guidewire should
not be removed until one is certain that the stricture has been adequately covered by the stent. In
extremely tight strictures, the delivery system
may not be easily withdrawn as it may be constrained by the unexpanded stent. In addition, the
WallFlex stent has a shelf on the distal end of the
delivery system, which may catch on the wires.
The assistant should place the stent in the predeployment position to match the sheath against the
distal end of the stent and resolve this shelf. The
endoscopist simultaneously needs to advance
the delivery catheter as this maneuver tends to
pull the distal nose proximally and may dislodge
the stent proximally.
Proper positioning of the stent within the
stricture is con fi rmed fl uoroscopically by a waist
within the stent (Fig. 11.7d ). Contrast can be
injected through the working channel and into
the stent to assess complete patency. Leaving the
wire in place allows additional stent(s) to be
deployed in overlapping fashion, if needed or for
postdeployment balloon dilation. If overlapping
stents are required, it is essential to have at least
2 cm overlapping after deployment, since with
further expansion after placement, the stents may
shorten and separate. Balloon dilation is usually
not needed as the stent will expand on its own
and postdeployment dilation has been shown to
induce perforation.
For strictures in the second duodenum, there is
some debate about whether or not the proximal
end of the stent should remain in the duodenum
or in the gastric antrum because of the potential
difference in functional result. Stent-induced perforation may occur when the proximal end of a
stent with sharp wires remains in the duodenum
[ 19 ] . Newer stents with rounded edges may
reduce this complication and allow for more
physiologic gastric emptying.
Non-Through-the-Scope Stent Insertion
Non-TTS stent placement is most often used
when placed by interventional radiologists and
when endoscopists use stents that cannot be
placed TTS (e.g., use of esophageal stents). The
dif fi culty with non-TTS placement is the lack of
mechanical advantage in lesions distal to the
168
T. Baron
Fig. 11.7 Palliation of malignant obstruction near the
ligament of Treitz due to gastric cancer. ( a ) A colono-
scope is in position at the lesion. An occlusion balloon
is in fl ated and contrast injected under pressure. No contrast passes. ( b ) A rotatable biliary sphincterotome with
small diameter hydrophilic wire is passed across the
stricture. ( c ) Contrast is injected con fi rming passage
into small bowel. ( d ) Radiographic image immediately
after stent deployment. ( e ) Endoscopic photo of
deployed stent