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212
T. Baron and R.A. Kozarek
Fig. 14.5 Barium swallow. A high-risk achalasia patient
( a ) treated with covered esophageal stent ( b, c ). Repeated
stent migration into the stomach despite multiple clip
placements
an esophageal neo-lumen after rendezvous reconnection of the proximal esophagus in patients
who developed aphagia and esophageal obliteration after radiation for head and neck cancer [ 51 ]
(Fig.
14.6 ).
Complications
remained fairly stable over the years and mainly
consist of perforation, aspiration pneumonia,
hemorrhage, and severe pain, the latter occurring
in approximately 10% of patients. Delayed complications following stent placement include
bleeding, fi stula formation, GE re fl ux, stent
migration, food bolus obstruction, and embedding of uncovered portions at either end of the
stent. Repositioning or removal of a migrated
stent can be achieved if tissue ingrowth has not
occurred using a retrieval forceps, an in fl ated balloon catheter, or a polypectomy snare.
Most experts advocate the use of proton-pump
inhibitors (PPIs) for patients in whom the stent
crosses the lower esophageal sphincter to prevent
re fl ux symptoms. PPIs improve re fl ux symptoms,
but not the risk of aspiration. FCSEMS with an
anti-re fl ux mechanism are available.
Complications associated with SEPS are
similar to those associated with SEMS [
52 ] . The
need for repeat stent placement ranges from 24%
to 100% in cases reported to date. Stent migration
is the most common complication with frequency
ranging from 7% to 75% of the cases. Overall, the
rate of migration of SEPS seems to be higher than
that of PCSEMS. In most instances, the stents
have been removed endoscopically, and anecdotal
reports on the use of endoscopic clips to secure
the stent to the mucosa are disappointing. The
presence of short strictures and proximal as well
as distal strictures is one of the factors that may
promote stent migration. In addition, the risk of
fatal bleeding from SEPS placement needs to be
emphasized to the patient and caregivers.
Less common complications following selfexpandable stent placement include epidural
abscess [ 53 ] , tracheoesophageal fi stula [ 54 ] , and
acute bronchial obstruction even in the absence of
a stricture [ 55 ] . Unusual complications of BDSES
include severe epithelial hyperplasia [ 56 ] and
stent collapse with esophageal obstruction [
57 ] .
Complications of SEMS for benign disease are similar to that of malignant disease, and the common
complications are listed in Table
14.1 and may be
classi fi ed as intraprocedural and postprocedural
(immediate and delayed). Procedure-related
complications after SEMS placement have
Conclusions
The use of self-expandable stents seems to be
safe and effective for the treatment of a variety of
benign esophageal diseases, especially for closure
of anastomotic leaks and perforations. However,
21314 Esophageal Stents: Benign
Fig. 14.6 Rendezvous reconnection of hypopharynx
and proximal esophagus working through the mouth
and percutaneous endoscopic gastrostomy (PEG) tract,
the data on benign esophageal strictures has been
mixed. Multicenter, prospective studies are
needed to evaluate the late-complication rate and
long-term effectiveness in this latter, dif fi cult-totreat patient population.
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21514 Esophageal Stents: Benign
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Self-Expanding Metallic Stents
for Malignant Hilar Biliary
Obstruction
Mustafa A. Tiewala and Martin L. Freeman
1 5
Management of malignant hilar biliary obstruction
represents a major challenge for therapeutic endoscopists. There is substantial controversy regarding
the optimal method for diagnosis and palliation of
jaundice with respect to timing, route, method, and
extent of drainage . Traditional methods of endo-
scopic retrograde cholangiography (ERCP) and
drainage using standard opaci fi cation techniques
and plastic stents have generally resulted in poor
outcomes with ineffective palliation and frequent
complications, especially cholangitis. Optimal
results of diagnosis, staging, curative resection,
and/or palliation are achieved using an advanced
multidisciplinary team approach that incorporates
maximal noninvasive imaging before any intervention is undertaken. It is important to decide in
advance whether a patient is a candidate for surgical resection and determine further evaluation and
therapy accordingly. Newly re fi ned techniques
including endoscopic ultrasound with fi ne needle
aspiration, multidetector CT, and especially MRI
and MRCP facilitate accurate diagnosis, evaluation, and staging of disease and allow optimal
planning of drainage for the endoscopist or inter-
M. A. Tiewala , M.D.
Division of Gastroenterology , Hennepin County
Medical Center, 701 Park Avenue ,
Minneapolis , MN 55415 , USA
M. L. Freeman , M.D. ( )
Division of Gastroenterology, Hepatology and Nutrition ,
University of Minnesota , 406 Harvard St SE, MMC36,
55455 Minneapolis , MN , USA
e-mail: freem020@umn.edu
ventional radiologist if indicated. Tissue diagnosis
can be made by ERCP with brush cytology, by forceps biopsy obtained under fl uoroscopic guidance
or under direct cholangioscopy, and by endoscopic
ultrasound with fi ne needle aspiration, particularly
of surrounding masses or lymph nodes. Intraductal
ultrasound may occasionally assist with differentiation of malignant from benign obstruction, but
has the disadvantage of requiring ERCP and does
not provide a tissue diagnosis. Use of ERCP or
percutaneous transhepatic cholangiography (PTC)
should be limited primarily to palliation of jaundice in patients with unresectable tumors and to
help establish a tissue diagnosis in ambiguous
cases. Proof of malignancy or differentiation of
malignant from benign causes of hilar obstruction
such as IgG4 cholangiopathy can sometimes be
challenging.
Hilar tumors can be classi fi ed into three main
types based on the origin of the tumor. The fi rst
category includes tumors originating from the
bile duct, including adenocarcinoma, the most
common of which is cholangiocarcinoma. The
second category involves local extension into
the hilum by a tumor arising in an adjacent
structure, such as the gallbladder, liver, or pancreas. The third category includes metastases
from solid tumors, such as carcinoma of the
breast, colon, or ovaries, or from lymphoma.
Differentiation of metastatic lesions from primary bile duct tumors can sometimes be dif fi cult. Patients with primary bile duct tumors may
be candidates for surgical resection, whereas
R. Kozarek et al. (eds.), Self-Expandable Stents in the Gastrointestinal Tract,
DOI 10.1007/978-1-4614-3746-8_15, © Springer Science+Business Media New York 2013
217
218
those with extension of adjacent tumors and
those with hilar metastases from distant primary
sites are generally not. Attempt at curative surgical resection is appropriate for certain patients
and almost always includes partial hepatectomy.
Bismuth-Corlette classi fi cation alone does not
determine resectability. Treatment should be
governed by the clinical status of the patient and
whether the patient is a surgical candidate. Liver
transplantation is offered after aggressive neoadjuvant therapy at a limited number of centers
for patients with locally advanced but unresectable primary tumors such as cholangiocarcinoma. Optimal therapy of hilar tumors requires
a setting in which a substantial volume of
patients with similar problems are seen, and
advanced hepatobiliary surgery, interventional
endoscopy, and interventional radiology is
available.
As most patients with malignant hilar biliary
obstruction are not surgical candidates, the focus
of care is most often on palliation of jaundice
using endoscopically or percutaneously placed
stents. Additional palliative options for unresectable bile duct tumors include surgical bypass,
intraluminal and external beam radiation therapy,
chemotherapy, and photodynamic therapy. Even
if not resectable, some hilar cancers, particularly
cholangiocarcinomas and metastases from breast
carcinomas, may grow slowly and allow for prolonged patient survival of up to several years with
proper drainage, placing a premium on optimal
stenting and palliation. Ineffective drainage,
regardless of route, and associated cholangitis
are major determinants of early mortality [ 1 ] .
Increasing evidence suggests that metallic stents
are superior to plastic stents for palliation of hilar
malignant biliary obstruction in most circumstances, if optimally positioned. It remains
unclear in which circumstances a single stent is
suf fi cient for effective palliation and avoidance
of cholangitis in excluded segments. With
improvements in technology of guidewires, catheters, and particularly of metallic stents and their
delivery systems, placement of more than one
stent is technically feasible in the majority of
circumstances.
M.A. Tiewala and M.L. Freeman
Bismuth-Corlette Classi fi cation
and Liver Segmental Anatomy
Hilar tumors can be characterized by level of
ductal obstruction, commonly referred to as
Bismuth-Corlette classi fi cation [ 2 ] (Fig. 15.1 ). In
type I lesions, the stenosis lies at the level of the
common hepatic duct within 2 cm of the bifurcation, with intact communication between right
and left hepatic ducts. In type 2, there is separate
obstruction of the takeoff of the right and left
hepatic ducts. Type 3A lesions involve secondary
branches of the right intrahepatic duct, and type
3B secondary branches of the left intrahepatic
duct with intact contralateral ducts. Type 4 lesions
involve bilateral secondary or tertiary branch duct
involvement or may be multifocal.
Bismuth-Corlette classi fi cation has a role in
determining extent of drainage, but its importance
may have been overemphasized. Understanding
hepatic segmental anatomy and sectoral ductal
anatomy with its many variations is a prerequisite
for optimal endoscopic drainage. Both CT scan and
three-dimensional MRCP, which is now routinely
performed at almost all major and many smaller
medical centers, greatly facilitate understanding of
hepatic segmental and ductal anatomy. A number of
websites have instructional materials on this topic,
and endoscopists are encouraged to visit them.
Seven of the eight liver segments are usually
of substantial size, excluding segment one which
drains the caudate lobe. The segmental ducts
typically coalesce to form three main sectoral
ducts – the right anterior sectoral duct (draining
segments V and VIII), the right posterior sectoral
duct (draining segments VI and VII), and the left main
hepatic duct (draining segments II–IV). Atrophy
and variations in ductal anatomy have major
implications for endoscopic stent placement.
Segments may atrophy as a slowly growing tumor
obstructs one sectoral duct over a prolonged
period before there is obstruction of the contralateral side and thus presentation with jaundice.
Drainage of such atrophic segments, even with
dilated ducts, is usually ineffective at relieving
jaundice and may lead to recurrent cholangitis.
Fig. 15.1 Bismuth-Corlette classi fi cation of hilar tumors
21915 Self-Expanding Metallic Stents for Malignant Hilar Biliary Obstruction
In addition, there is substantial variation in segmental and sectoral anatomy (Fig. 15.2 ). For
example, the right posterior sectoral duct (draining segments VI and VII) drains into the left
hepatic duct in about one-fourth of the patients,
such that a single left hepatic duct stent would
drain the entire left lobe and the right posterior
sectoral duct, thus draining the entire liver saved
for the right anterior duct. In this situation, a left
duct stent would actually drain a substantial portion of the right lobe. In other patients, there may
be a trifurcation with right anterior and posterior
sectoral and left ducts joining together, such that
a similar bifurcation tumor might involve three
equivalent sectoral ductal obstructions. In that
situation, the same left hepatic duct stent as
placed in the previous example would only drain
one-third rather than two-thirds of the liver. In
some other patients, the right posterior sectoral
duct enters the common hepatic duct below the
bifurcation, such that a single stent in the left
hepatic duct would actually drain two-thirds of
the liver. Because more than one stent may be
placed in the same side of the liver (usually the
right anterior and right posterior sectoral ducts),
or one stent may actually drain both sides of the
liver, the concept of unilateral or bilateral drain-
age may be somewhat outmoded and best referred
to as single or multiple stents based on sectoral
anatomy.
Single or Multiple Stents?
Whether palliative endoscopic stenting should be
unilateral (perhaps best referred to as single) or
bilateral (perhaps best referred to as multiple) has
been debated for many years, with varying opinions based on anecdotal evidence and con fl icting
data. The principle governing drainage had been
that only 25–50% of the liver needs to be drained
for palliation, but until recently that assumption
had not been formally investigated. Problems that
arise from endoscopic stenting of hilar malignancy are mainly related to inadequate drainage,
infection in undrained segments, or later from
stent occlusion or malfunction. The prevailing
point of view had been for many years that bilateral drainage was preferred; however, supporting
data were mainly from retrospective case
220
M.A. Tiewala and M.L. Freeman
Fig. 15.2 Anatomic variations in insertion of right poste-
rior sectoral duct (shown in white ) in three hypothetical
patients with identical hilar tumors, showing implications
for stenting. At left , trifurcation with three sectoral duct
obstructions; in middle , insertion of right posterior duct
controlled series that involved the use of plastic
stents and in which selective duct cannulation
and opaci fi cation was not performed. In one
classic retrospective study using plastic stents in
141 patients with hilar tumors, survival was
signi fi cantly shorter in patients with bilateral
opaci fi cation and unilateral stenting (46 days)
compared with unilateral opaci fi cation and unilateral stenting (145 days) or bilateral opaci fi cation
and bilateral stenting (225 days) [ 3 ] . Problems
with these and other retrospective data were that
multiple segmental ducts were contaminated but
not drained and that many confounding variables
other than drainage affect survival.
More recently, a number of authors have
reported unilateral stenting to be generally satisfactory as long as selective access and opaci fi cation
techniques are used. One study reported 86%
ef fi cacy and minimal complications with unilateral drainage of hilar tumors using MRCP to target endoscopic placement of single plastic stents,
but the practicality of this approach was limited by
the need for routine stent changes every 2 months
(more than 4 per patient) [ 4 ] . A prospective
into left duct, with two points of obstruction with one
obstructing two sectors and another obstructing single
sector; at right , low insertion of right posterior duct below
bifurcation, with tumor separately obstructing two
sectors, third below tumor
randomized trial involving plastic stents suggested
that selective unilateral endoscopic drainage was
superior to bilateral drainage, with signi fi cantly
fewer technical failures (11.4% vs. 23.1%) and,
thus, less contamination of undrained segments,
resulting in fewer early complications, less early
cholangitis (8.8% vs. 16.6%), and no difference in
late complications [ 5 ] . Problems with these data
were a relatively low technical success rate and
the fact that results may not translate to metallic
stents. The data do support the concept that endoscopic placement of bilateral large-bore plastic
stents may be dif fi cult or sometimes impossible,
and failure to place a second stent after extensive
manipulation may lead to serious complications.
Unilateral targeted stenting is substantially
easier to perform and allows easier endoscopic
reintervention.
There are a number of prospective and retrospective case series demonstrating reasonable
safety and ef fi cacy of single metallic stents for
hilar tumors [ 6– 9 ] . In two prospective series
involving 35 and 61 patients, respectively,
approximately half of whom had Bismuth III and
22115 Self-Expanding Metallic Stents for Malignant Hilar Biliary Obstruction
IV lesions, single MRCP-targeted metallic stents
resulted in resolution of jaundice in 77% and
86%, with complications occurring in 0 and 8%
of cases, median stent patencies of 5.4 and
5.6 months, and repeat intervention required in
29% and 26%, respectively [
7, 8 ] . Of note is that
approximately one in fi ve patients did not achieve
palliation of jaundice with a single stent.
Most of the data comparing single versus
multiple stents involve plastic endoprostheses.
There are only two retrospective studies comparing outcomes of bilateral versus unilateral metallic stents. A retrospective study compared
outcomes of metallic stents in 17 unilateral and
29 bilateral cases [ 10 ] . Successful drainage was
achieved in nearly all patients (100% and 96%,
respectively), with a trend toward fewer early
complications with unilateral stents (0% vs.
10%), similar late complications (65% vs. 54%),
but with substantially longer patencies for bilateral stents overall (P = 0.009), especially for
those patients with cholangiocarcinoma. Another
retrospective study of 82 patients undergoing
metallic stenting for hilar tumors found no
signi fi cant difference between unilateral versus
bilateral metallic stents with respect to median
survival, stent patency, or complication-free survival time, but did fi nd a signi fi cantly higher rate
of liver abscess (17.6%) for bilateral versus unilateral (1.5%) stents [ 11 ] . Thus, the results of
these two studies are con fl icting with respect to
value of dual versus single metallic stents. As
with all retrospective and univariate analyses,
these studies do not allow for adjustment for
confounding variables such as tumor stage, functional status, Bismuth class, or other potentially
important factors.
One study of palliative stenting has moved
beyond the concept of unilateral and bilateral
and has applied understanding of liver parenchymal volume and sectoral duct anatomy to
hilar tumor drainage. In a retrospective study of
107 patients with Bismuth II–IV tumors undergoing palliative stenting with mostly plastic stents,
CT scan was used to determine volume of liver in
three liver sectors: the left sector (segments
II–III), right posterior sector (segments VI and
VII), and right anterior sector (segments V and
12 ] . Segment IV could fl ow into the right
VIII) [
or left duct and was accounted for based on
individual biliary anatomy. On each CT slice,
the relative area of each sector was calculated as
a fraction of the entire liver area. Each sector
was then classi fi ed as 30%, 30–50%, and > 50%
of the total liver volume. If the sector was less
than 30%, it was considered atrophied, and if
the tumor extended to greater than 75% of the
total volume, then this sector also considered
less than 30%. The primary outcome of this
study was the effectiveness of drainage as demonstrated by a decreased bilirubin of more
than 50% of the pretreatment value on day 30.
In the group with more than 50% of liver volume
drained, the rate of effective drainage was
signi fi cantly higher with less cholangitis and longer survival than the less than 50% group. Thus,
the most important take-home points from this
novel study were the following: (1) More than
50% drainage of liver volume based on hepatic
sectors was a strong predictor of drainage effectiveness, especially in Bismuth type three patients.
(2) Intubating an atrophied sector was ineffective
and was associated with increased risk of cholangitis and should thus be avoided. (3) More than
50% volume drainage is associated with a longer
survival. This study involved primarily use of
plastic stents. Whether or not these results can be
generalized to metallic stents is unclear. An
important contribution of this study is steering
away from the concept of unilateral or bilateral
toward single or multiple sectoral duct drainage,
which sometimes involves two stents in the right
hepatic duct sectors rather than a left and right
hepatic duct stent.
To summarize, currently available data are
con fl icting for the value of bilateral versus unilateral stents, whether plastic or metallic. What is
clear is that enhanced understanding of liver segment anatomy and drainage, in addition to individual tumor characteristics, and careful review
of axial and reconstructed CT and MRCP images
will likely lead to best outcomes (Fig. 15.3a, b ).
Selective access techniques, and drainage of at
least 50% of the liver volume without infecting
remaining segments, seem to be primary determinants of favorable results.
222
M.A. Tiewala and M.L. Freeman
Fig. 15.3 ( a ) MRCP showing hilar tumor with apparent
communication of intrahepatic ducts (possible Bismuth I
or II) and ( b ) three-dimensional rotation of MRCP show-
ing vertical projection, revealing multiple points of
obstruction (Bismuth IV)
Plastic or Self-Expanding
Metallic Stents?
It has been clearly established that for distal bile
duct tumors, metal stents are superior to plastic
stents with respect to patency and overall cost in
patients with a minimum of 3–4 months survival
[ 13 ] . For hilar tumors, there remains substantial
difference of opinion and sparse data regarding
choice of metal versus plastic stents [ 14– 16 ] .
There are many theoretical reasons why plastic
stents would be less effective for hilar tumors
than for distal tumors: the excessive length and
lack of conformability impair bile fl ow, lead to
early occlusion, and promote migration, and the
material allows colonization of stents with
bio fi lm, which in turn leads to infection of
undrained segments and resultant cholangitis; the
lack of side holes in standard stents occludes secondary branch ducts, and the relatively large
insertion diameter and limited mechanical leverage render placement of multiple large-bore
stents technically challenging in stenotic and
complex strictures. In contrast, uncovered metallic
stents have major theoretical advantages for
hilar tumors, including open mesh to allow
drainage of secondary branch ducts, conformability to tortuous intrahepatic ducts, and relative
lack of bacterial bio fi lm once the stent becomes
embedded in biliary mucosa.
There are, to date, only three studies comparing
metallic to plastic stents in hilar tumors, of which
one was a retrospective case-control study [ 17 ] ,
one was a prospective case control with only
short-term follow-up [ 18 ] , and one study from
two decades ago was a randomized trial [ 19 ] . In
the prospective randomized trial published in
1993, bilateral large-bore plastic stents and bilateral self-expanding metal stents (8 mm) were
compared in the palliative treatment of obstructive
jaundice in 20 patients with Bismuth II through
IV hilar malignancies [ 19 ] . Stents were placed by
combined percutaneous and endoscopic route.
Long-term (> 30 days) stent failure was observed
in 50% of the plastic group and 18% of the metal
stent group, a difference which did not quite
reach statistical signi fi cance in this small study.
However, even with the small sample size, the
number of repeat interventions and hospitalizations for treatment of stent complications, as well
as estimated overall cost of care, were signi fi cantly
higher in patients treated with plastic compared
with metallic stents. In a prospective multicenter
case-control study, the 30-day outcomes of plastic
versus self-expanding metallic stents were compared for the palliation of malignant hilar biliary
obstruction [ 18 ] . Most stents were unilateral in
both groups. Adverse outcomes including cholangitis, stent occlusion, migration, perforation,
and/or the need for unplanned endoscopic retrograde cholangiopancreatography or percutaneous
transhepatic cholangiography occurred in 11/28
(39.3%) patients with plastic versus 4/34 (11.8%)
with metal stents (P = 0.017). By logistic regression, factors associated with adverse outcomes
included plastic stent placement (odds ratio 6.3)
and higher serum bilirubin, but not study center
location or Bismuth class. Finally, in a recently
published retrospective case-control study of 100
patients with inoperable cholangiocarcinoma
undergoing palliative stenting, the clinical effectiveness (including stent patency), complication