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Table 15.1 Complications of metal stenting for hilar
tumors
Placement in patients with benign disease
Placement in wrong segmental ducts
Precluding resection
Tumor ingrowth
Stone formation
Reactive hyperplasia
Cholangitis – early or late
Erosion into vessels (bleeding)
rate, and need for salvage percutaneous transhepatic biliary drainage of SEMS and plastic stents
were compared [ 17 ] . Median patencies were
1.86 months in the plastic group and 5.56 months
in the SEMS group (P < 0.0001). A mean of 1.53
and 4.60 reinterventions were performed in the
SEMS and plastic groups, respectively (P < 0.05).
Median survival was not different between the
two groups.
Overall, it seems from the available but limited data that metallic stents are superior to plastic stents for palliation of hilar tumors with
respect to early complications, stent patencies,
and need for repeat interventions. However, there
are several caveats that uniquely pertain to metallic stents for hilar as opposed to distal tumors
(Table 15.1 ). Covered stents generally are not
appropriate for hilar tumors because of occlusion
of secondary branch ducts. As such, hilar metallic stents are generally not removable endoscopically or even surgically. Placement of a metallic
stent into intrahepatic ducts renders not only
tumor staging but resection and/or liver transplantation dif fi cult or impossible. Because there
are a number of benign conditions that mimic
hilar tumors, and tissue diagnosis of malignancy
is often dif fi cult to obtain, there is a further premium on accurate diagnosis and staging prior to
consideration of metallic stent placement. As a
result of these factors, and the theoretical and
technical complexity of placement of one or more
metallic stents, hilar tumor drainage is a highly
specialized procedure that is best performed by
expert endoscopists in the context of a specialized center dealing with all aspects of disease
management.
22315 Self-Expanding Metallic Stents for Malignant Hilar Biliary Obstruction
Technical Aspects of Metallic Stent
Insertion for Hilar Tumors
Two fundamental SEMS designs that are available
today include the spiral-cell type and the laser-cut
open-cell type (Fig. 15.4a, b ). Primary differences
are that spiral stents foreshorten substantially
during delivery, while open-cell stents do not,
and spiral stents tend to have a tighter mesh than
open-cell stents. Spiral stents include Wall fl ex
and Wallstent (Boston Scienti fi c, Natick MA).
The Wall fl ex is made of Platinol, is MRI safe,
and has a spiral-braided wire construction with
relatively small cells. These stents probably offer
the most radial force; however, they are sometimes dif fi cult to position accurately due to foreshortening at both ends. The high axial force of
these stents tends to straighten the duct and may
lead to problems in hilar strictures due to tortuosity of the intrahepatic ducts. The dense mesh renders access through the stent mesh for “Y” stent
placement very dif fi cult, thus potentially locking
out any undrained ducts from endoscopic access.
The Niti-S (TaeWoong Medical, Goyang-Si,
Korea) is made of nitinol and is a wire, fl exible,
fi ne mesh tubular prosthesis with a relatively
larger cell design and substantial conformability
with tortuous ducts. The D type is uniform
throughout; the Y-type stent is designed with a
wider mesh in the center of the stent to facilitate
stent placement in a “Y” con fi guration.
Laser-cut nitinol stents include Zilver (Cook
Endoscopy, Winston-Salem, NC), which is a selfexpandable stent made of nitinol with a wide
mesh open-cell design and minimal foreshortening. A major advantage of the Zilver stent is the
smallest currently available outer diameter insertion
diameter (6 French) and high conformability to
tortuous ducts; a relative disadvantage is lower
radial force. Flexxus (ConMed, Utica, NY) is
quite similar to the Zilver stent, but has a guntype deployment system, which allows easy stepwise release of the stent. The X-Suit NIR biliary
stent (Olympus, Center Valley, PA) is similar to
the previous two stents but has a larger diameter
delivery system. The JOSTENT SelfX (Abbott
224
M.A. Tiewala and M.L. Freeman
Fig. 15.4 ( a ) Spiral con fi guration metallic stent (Wall fl ex). ( b ) Open-cell laser-cut stent (Zilver stent)
Laboratories, Abbott Park, IL) is an uncovered
self-expanding nitinol stent with minimal foreshortening. All of these open-cell stents allow
placement of stent-through-stent in a “Y”
con fi guration without special modi fi cation.
Techniques for Single and Multiple
Selective Stent Placement
Once the decision has been made to place metallic stents, whether primarily or replacing plastic
stents, it is essential to carefully review imaging,
including both axial and reconstructed views of
the ducts. MRCP with three-dimensional reconstruction is highly recommended whenever
possible, although coronal views of CT may also
provide useful information. At index, ERCP contrast should only be injected to below the stricture
to avoid contaminating undrained segments.
Biliary sphincterotomy is recommended to reduce
the otherwise elevated risk of post-ERCP pancreatitis in hilar tumor stenting and allow easy
repeated access (Fig. 15.5 ). Sphincterotomy may
not always be necessary with metallic stents
positioned above the papilla. The goal should be
drainage of at least 50% of the liver parenchyma,
avoiding atrophic segments, and the number and
position of desired stents planned in advance.
The decision to place more than one metallic
stent is in fl uenced by volume of liver drained,
presence of contamination of multiple sectoral
ducts because of previous plastic stent placement,
or cholangitis, and contamination during duct
access and injection of contrast.
Fig. 15.5 Three guidewires placed through biliary
sphincterotomy in patient with hilar tumor
Placement of single metallic stents is straightforward (Fig. 15.6 ). Enough contrast is instilled
in the desired segments only to de fi ne the upper
and lower extent of the intended drainage and
only after selective guidewire access. The stent is
then positioned with at least 2 cm above the
stricture and 2 cm below the stricture, usually
resulting in suprapapillary positioning. More
stents can be overlapped in tandem if it is desired
to extend the stents through the papilla. There is
theoretical concern that transpapillary positioning
of metallic stents is associated with more cholangitis due to enteric-biliary re fl ux [ 20 ] . In the
authors’ opinion, open-cell stents should be used
22515 Self-Expanding Metallic Stents for Malignant Hilar Biliary Obstruction
Fig. 15.6 Case illustrating use of MRCP for selective unilateral stent placement in left hepatic duct of patient with
hilar cholangiocarcinoma. ( a ) MRCP showing Bismuth
IIIb cholangiocarcinoma arising from right hepatic duct
with multiple points of obstruction and atrophy of the right
lobe and hypertrophied left lobe. In this patient, insertion
of single left hepatic duct stents indicated ( b ) ERCP with
for single metallic stent placement in case subsequent placement of contralateral stent-through-stent
is required. Access through a dense mesh stent is
dif fi cult (Fig. 15.7 ) and sometimes impossible
balloon in fl ated across stricture, but tip of catheter in segment IV and no access deep into segment II or III. ( c ) Stent
positioned but deployment here not ideal, would not drain
segments II or III adequately. ( d ) Deep-wire positioning
into segment II duct with balloon rein fl ated. ( e ) Metallic
stent positioned correctly. ( f ) Proper positioning of open-
cell metallic stent into left hepatic duct
endoscopically and may require percutaneous
intervention (Fig. 15.8 ).
The original technique for placement of multiple
stents typically involved endoscopic placement of
226
M.A. Tiewala and M.L. Freeman
Fig. 15.7 Sequence showing problems with dense mesh
spiral stent extending beyond bifurcation; salvage using
Soehendra stent extractor as dilator to rupture mesh of
stent. ( a ) Wall fl ex stent had been placed into right hepatic
duct across takeoff of left hepatic duct, with subsequent
cholangitis and purulent drainage from right lobe.
Fig. 15.8 Demonstration of hazards of placement of dense
mesh metallic Wallstent in hilar tumor: patient with unresectable hilar cholangiocarcinoma with non-atrophic left
lobe, in whom dense mesh spiral-type single metallic stent
in left lobe failed to relieve jaundice, could not be pene-
trated at repeat ERCP, requiring percutaneous access and
placement of Y con fi guration right hepatic duct stent. ( a ) CT
scan showing hilar tumor with mildly hypertrophied left
( b ) Steerable cannula (SwingTip, Olympus) and
hydrophilic-tipped guidewire used to angle through mesh
of stent into left hepatic duct. ( c ) 8,5-French Soehendra
stent extractor (Cook Endoscopy) used to core tract
through mesh of Wall fl ex stent to rupture mesh, with air
cholangiogram visible in left hepatic duct
lobe, subsequently single left stent placed as predicted to be
adequate for drainage. ( b ) Percutaneous access to obstructed
right hepatic duct because of persistent jaundice; after
repeat ERCP showed patent left hepatic duct stent, but unable
to traverse dense mesh to access right hepatic duct. ( c ) After
percutaneous placement of second stent-through-mesh
of endoscopically placed left hepatic duct stent in Y
con fi guration, with successful relief of jaundice
one stent and percutaneous placement of the contralateral stent via a percutaneous or combined
endoscopic-percutaneous rendezvous technique
[ 21 ] . Subsequently, improvements in endoscopic
techniques for accessing multiple sectoral ducts
and improved stent characteristics with smaller
insertion diameters have facilitated stent placement such that success rates for multiple endoscopic stents now approach 100%. Dual metallic
stent placement by the endoscopic route is generally done using the side-by-side con fi guration or
stent-through-stent (Y) con fi guration. The earliest
reports of multiple stent placement mostly
included side-by-side placement with the stents
protruding through the papilla (Fig.
15.9 ) [ 21 ] . In
this method, dual wires are placed, the strictures
balloon dilated, and fi rst one stent is deployed,
then the second stent passed beyond the fi rst stent
and into the contralateral duct. Using Wallstents
as originally reported, the 30–40% foreshortening
requires a stent of 10 cm or longer length or overlapping stents to span the distance from the intrahepatic ducts across the papilla. Despite optimal
positioning during ERCP, foreshortening of the
22715 Self-Expanding Metallic Stents for Malignant Hilar Biliary Obstruction
Fig. 15.9 Placement of bilateral Wallstents using side-byside technique and extending across the papilla. ( a )
Cholangiogram showing Bismuth II cholangiocarcinoma.
( b ) Balloon dilation of right (and left not shown) duct
stents may result in eventual contraction of the
stents upward across the papilla. During placement of dual side-by-side metallic stents positioned above the papilla, the second stent may not
pass the opened bottom of the fi rst stent, rendering second stent placement impossible and creating a potential hazard for undrained segmental
cholangitis. Although complex modi fi cations of
techniques have been reported to overcome this
obstacle, including placement of large-bore plastic stent as a conduit, the sequential side-by-side
technique is limited [ 22 ] .
Simultaneous deployment of side-by-side
stents was fi rst described using a prototype large
caliber ERCP duodenoscope [ 23 ] . Subsequently,
the availability of very small caliber (6 French)
strictures. ( c ) First stent has been deployed in left hepatic
duct and extending across papilla, with second guidewire
left in place beside fi rst stent. ( d ) Second stent has been
passed beside left stent and deployed in right hepatic duct
delivery systems has rendered the technique of
simultaneous positioning of two side-by-side
stents prior to deployment feasible and quite
easy using standard therapeutic duodenoscopes
with a 4.2-mm working channel. Technical success rates approach 100% with these prostheses
(Figs. 15.10 , 15.11 , and 15.12 ). The stents can
be released sequentially or simultaneously.
Challenges with side-by-side simultaneous stent
deployment include lining up the distal ends of
the stents exactly. Due to the fact that the distal
bile duct is often small caliber (6–8 mm) in
patients with hilar obstruction, presence of dual
8-mm stent results in overcrowding of the
distal duct and nearly inevitable compression of
one stent by the other even if exactly aligned.
Fig. 15.10 Two standard metallic stents in Y con fi guration
with one inserted through the other without special
modi fi cation (Flexxus, ConMed)
Fig. 15.11 Different view of Y con fi guration Flexxus
stents showing minimal caging effect with large lumen
Fig. 15.12 Sequence showing simultaneous side-by-side
deployment of 6-French Zilver stents in patient with
Bismuth IIIa tumor. ( a ) MRCP showing Bismuth IIIa
cholangiocarcinoma with mild atrophy of left lobe. Plan is
to drain left sector (segments II–IV) and right anterior sec-
toral duct (segments V and VIII). ( b ) Dual 6-French 8-mm
diameter, 8-cm length Zilver stents have been positioned
simultaneously with bottom ends exactly even inside
distal bile duct above papilla. ( c ) After simultaneous
deployment, there is compression of distal end of one
stent by the other, a common problem with this technique
especially in patients with small caliber bile duct
22915 Self-Expanding Metallic Stents for Malignant Hilar Biliary Obstruction
Fig. 15.13 Sequence showing MRCP-targeted placement of bilateral metallic Zilver stents in Y con fi guration
in a patient with Bismuth II tumor. ( a ) MRCP showing
Bismuth II tumor 1. ( b ) After wires placed in left and right
anterior sectoral ducts, fi rst metallic stent positioned in
left hepatic duct. ( c ) After deployment of left hepatic duct
As a result, later selective access for cleaning or
re-stenting can be dif fi cult.
A stent-through-stent technique (Y con fi guration)
was initially described using spiral stents such
as the Wallstent, but was very challenging due to
the tight mesh of such stents. Subsequent proliferation of open-cell stents with small caliber
delivery systems has greatly facilitated placement
of Y stents (Fig.
15.13 ) [ 24– 27 ] . The Niti-S
Y-type stent was speci fi cally designed stent
to have a more open mesh in the central portion to theoretically facilitate bilateral stent
placement. However, conventional stents including
stent, additional guidewire passed through lumen of left
stent into right hepatic duct paralleling other right hepatic
duct wire, followed by balloon dilation of tract through
open-mesh stent into right hepatic duct. ( d ) After deploy-
ment of bilateral Zilver stents in Y con fi guration
Zilver, Flexxus, X-Suit, and JOSTENT SelfX are
easily placed using the stent-through-stent technique. Not only can this be done at initial placement, but if a single stent fails to relieve jaundice,
or results in cholangitis such that a second stentthrough-stent is later necessary, salvage access
through the mesh can be done at a later date in
contrast to tight mesh spiral stents. The availability of steerable catheters (SwingTip, Olympus
Endoscopy) greatly facilitates selective access
through the open mesh for placement of a second
stent by angling the catheter tip perpendicularly
into the side of the initial stent. Hydrophilic wires
230
M.A. Tiewala and M.L. Freeman
and hybrid wires, both straight and angled tip,
can be used in combination with steerable
catheters to allow access to virtually any intrahepatic duct. Correlation with MRCP allows assurance that the desired duct is accessed before the
stent is deployed. Revision of Y stents is fairly
straightforward as access can generally be
obtained through the side of the mesh using
steerable catheters and guidewires (Figs. 15.14
and
15.15 ).
Complications of metal stenting occur in
approximately 8–15% of patients within the fi rst
Fig. 15.14 Sequence showing dual right hepatic duct
metallic stent in Y con fi guration in patient with Bismuth
IV cholangiocarcinoma with atrophied left hepatic duct,
separately obstructed right anterior and posterior sectoral
ducts. ( a ) MRCP showing Bismuth IV cholangiocarci-
noma with atrophied left hepatic duct, separately
obstructed right anterior and posterior sectoral ducts.
( b ) Axial image from MRCP showing atrophied left lobe.
( c ) Initial ERCP showing wire access into left hepatic
duct, no contrast injected, wire withdrawn and redirected
toward right lobe. ( d ) Selective access into right anterior
and posterior sectoral ducts, which were separately
obstructed. ( e ) Open-mesh stents placed into right ante-
rior and posterior ducts in Y con fi guration
23115 Self-Expanding Metallic Stents for Malignant Hilar Biliary Obstruction
Fig. 15.15 ( a ) After 4 months, ERCP is repeated because
patient developed cholangitis with purulent drainage from
atrophied left lobe duct; steerable catheter (SwingTip,
Olympus) is used to access through dual layer of mesh
into left hepatic duct. ( b ) Balloon dilation of tract through
mesh of stent into left hepatic duct. ( c ) Selective access
using steerable catheter into right anterior hepatic duct
stent for balloon dilation and clearance of debris.
( d ) Similar access into right posterior sectoral duct.
( e ) Zilver stent positioned in left hepatic duct through
mesh of initial stents. ( f ) Final deployment of salvage left
hepatic duct metal stent through dual right hepatic duct stents, for
total of three endoscopically placed Y con fi guration stents
in right anterior, right posterior, and left hepatic ducts
232
M.A. Tiewala and M.L. Freeman
30 days and in approximately 30% of patients at
some point during palliation (6–8). Early cholangitis is relatively rare (0–8%) using selective wireaccess techniques and avoidance of opaci fi cation
of undrainable segments. Major complications
include strategic errors, i.e., inappropriate placement in a benign stricture or a resectable lesion.
Placement in wrong segmental ducts can lead
to cholangitis and substantial dif fi culty with
revision, sometimes requiring percutaneous
salvage. Tumor ingrowth and reactive hyperplasia and stone formation may lead to late cholangitis. Occasionally, erosion of the stent into
vessels may result in bleeding.
Special Challenges with Metallic
Stents: Revision of Stents and
Photodynamic Therapy
Revision of single metallic stent is easy and
generally involves insertion of a new metallic
stent inside the previous stent. In general,
a second SEMS insertion in occluded SEMS
provides signi fi cantly longer patency time than
secondary plastic stents, but such data regarding
hilar tumors are limited [ 28 ] . Revision of multi-
ple hilar metallic stents can be challenging. As
previously mentioned, endoscopic access to both
stents for side-by-side intraductal stents can be
impossible and requires percutaneous access and
drainage with at least one of the stents. Endoscopic
access to Y stents using open-cell stents is relatively easy, using steerable catheters and hydrophilic-tipped guidewires. The lumens can be
cleaned of stone debris, balloon dilated, and/or
new stents placed within the old stents.
Photodynamic therapy (PDT) has been shown
to add survival advantage compared with plastic
stents alone in retrospective case-control studies
and in the one prospective randomized trial of
patients with inoperable cholangiocarcinoma
[ 29, 30 ] . There are limited reports demonstrating
the feasibility of combining PDT with metallic
stents for cholangiocarcinoma, with PDT performed
before or after metallic stent insertion [ 31, 32 ] . In
a retrospective case-control study of 21 patients
with hilar cholangiocarcinoma receiving bilateral
JOSTENT SelfX stents, the 8 patients who
underwent additional PDT had signi fi cantly
longer survival (16.5 months vs. 12.3 months),
without adding to cumulative hospital time [ 32 ] .
As of the current time, if PDT is intended in
conjunction with multiple metallic stents, sideby-side metallic stent placement with transpapillary extension is probably ideal to allow easy
access to both stent lumens.
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