Diagnostic and Therapeutic Endoscopy of Biliary Diseases

DISEASES OF THE BILIARY TRACT, SERIES #6
Rad Agrawal, M.D., Series Editor
Diagnostic and Therapeutic
Endoscopy of Biliary Diseases
by Yamini Subbiah, Shyam Thakkar, Elie Aoun
The therapeutic approach to biliary diseases has undergone a paradigm shift over
the past decade toward minimally invasive endoscopic interventions. This paper
reviews the advances and different diagnostic and therapeutic endoscopic approaches
to common biliary diseases including choledocholithiasis, benign and malignant biliary
strictures and bile leaks.
INTRODUCTION
With the introduction of innovative endoscopic
implements and options allowing for unprecedented
access to the biliary tree, the therapeutic
approach to biliary diseases has undergone a significant
paradigm shift over the past decade toward minimally
invasive endoscopic interventions. The days where biliary
diseases were exclusively managed surgically are
long gone, and much has changed since the first
reported biliary sphincterotomies in 1974. The recent
developments in peroral cholangioscopy and new
modalities of anchoring high resolution nasogastric
scopes in the bile duct offer the opportunity of direct
visualization of the bile duct lumen, which allows for
not only better identification of the underlying disease
process but also for targeting of biopsies and directed
lithotripsy. Other modalities that add to the growing
world of biliary luminal imaging include endoscopic
ultrasound (EUS) and intraductal ultrasound, which
enable the endoscopist to assess extrabiliary disorders.
EUS-assisted fine needle aspiration (FNA) tissue sampling
and immediate preliminary histopathologic analysis
also assist in immediate decision making and
therapeutics. Other recent advances include cuttingedge
molecular imaging technology that allows the
endoscopist to differentiate between benign and malignant
features, thus guiding decision making in real time.
COMMON BILE DUCT STONES
Over 98% of biliary disorders are linked to gallstones.
Stones are found in the common bile duct (CBD) in up
to 18% of patients with symptomatic cholelithiasis (1).
The vast majority of gallstones are cholesterol-rich,
form in the gallbladder and gain access to the CBD via
the cystic duct. De novo CBD stone formation is also
well described and is more common in patients of
Asian descent. These primary duct stones typically
have a higher bilirubin and a lower cholesterol content
and biliary stasis; further, bacterial infections have
been implicated in their pathogenesis (2,3). CBD
stones can lead to several complications including biliary
colic, obstructive jaundice and cholangitis.
Diagnostic Imaging Tests
While a minority of patients with a straight-forward
clinical presentation consistent with choledocholithiasis
may immediately be treated with ERCP, the vast
majority will benefit from diagnostic imaging studies
to confirm the diagnosis. Performing a diagnostic
ERCP with no prior imaging is not optimal due to the
potential risks associated with the procedure. Current
imaging modalities available for this purpose include
transabdominal ultrasound, regular- and high-resolu-
Yamini Subbiah, MD; Shyam Thakkar, MD; Elie Aoun,
MD, MS, West Penn Allegheny Health System, Division
of Gastroenterology, Hepatology and Nutrition,
Pittsburgh, PA. (continued on page 32)
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Diagnostic and Therapeutic Endoscopy of Biliary Diseases
DISEASES OF THE BILIARY TRACT, SERIES #6
(continued from page 30)
Figure 1. Endoscopic ultrasound showing stone in the
common bile duct; B) Gallstone extraction during ERCP.
tion computed tomography (CT) scans, magnetic resonance
cholangiopancreatography (MRCP) and EUS.
A transabdominal ultrasound remains the initial
test of choice in suspected cases of choledocholithiasis
because of its wide-spread availability and relatively
lower costs. Dilated ducts seen on ultrasound are
highly suggestive of biliary obstruction; however,
normal caliber ducts do not exclude a CBD stone.
Furthermore, differentiating between causes of
obstruction may also be difficult using this imaging
modality. Even still, while the transabdominal ultrasound’s
sensitivity in detecting choledocholithiasis is
low (ranging between 25% and 58%), its specificity
can be greater than 95% (4–6).
MRCP has catapulted to the frontlines of diagnostic
imaging and is typically the next test physicians
perform following an indeterminate transabdominal
ultrasound. Its sensitivity and specificity is 95% and
97%, respectively, in detecting the presence and level
of biliary obstruction. However, its sensitivity in detecting
stones is a function of stone size. While it ranges
from 67%–100% for stones larger than 1 cm, it can be
as low as 33%–71% in stones less than 6 mm (7–9).
Conventional CT scans have relatively good accuracy
(70%–94%) when it comes to identifying both the
presence and the cause of biliary obstruction (10,11).
A newer technique, the helical CT cholangiography
(hCTC), is yet another diagnostic option and allows
for three-dimensional reconstitution of images through
the use of volumetric data after the administration of
both oral and intravenous (IV) contrast. It has proven
to be beneficial in detecting CBD stones with a sensitivity
of ~87% and a high specificity of 97%, accounting
for an overall accuracy of 95% (12,13). However,
hCTC remains underused due to its limited availability
as compared with MRCP.
Over the past few years, the use of EUS as a diagnostic
imaging modality for CBD stones has gained
significant momentum. While more invasive than the
above methods, its associated risks and complications
are lower than those with ERCP. The sensitivity and
specificity at detecting CBD stones are 95% and 98%,
respectively, with a total accuracy of 96% (14,15).
Furthermore, studies have shown that in cases with
moderate or low clinical suspicion for choledocholithiasis,
the use of EUS may prevent up to 30% of unnecessary
ERCPs (16). Figure 1A illustrates an EUS
showing a stone in the CBD.
Endoscopic Therapy
Prior to the introduction of ERCP with sphincterotomy
in the 1970s, choledocholithiasis was mainly managed
with surgical extraction and open bile duct exploration
(17). Now, endoscopic techniques are first-line therapy
for CBD stones.
ERCP should be reserved for patients in whom a
therapeutic intervention is likely to occur. Nevertheless,
in certain rare situations where the diagnosis
remains uncertain despite multiple imaging modalities,
ERCP may be required. Once the diagnosis is suspected
or established, stone extraction and ductal
clearance become the therapeutic goals. Using a sideviewing
scope which allows direct visualization and
easy access to the papilla, cannulation of the bile duct
can be performed using a variety of available instruments
including cannulas and sphincterotomes. In the
hands of an experienced endoscopist, cannulation success
rates average ~95% (18). Once ductal access is
established, contrast can be used to opacify and visualize
the lumen. Typically stones are identified on the
cholangiogram as filling defects around which the contrast
flows. Opacification of the ducts also allows for
measurement of the severity of the dilation proximal to
the stone if any. Frey et al quote the accuracy of ERCP
at detecting CBD stones to be at 96% (19).
Once the stone is identified, the focus shifts to
extracting it from the duct. Figure 1B shows gallstone
extraction during ERCP. In the majority of cases, a biliary
sphincterotomy is needed prior to stone removal.
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Diagnostic and Therapeutic Endoscopy of Biliary Diseases
DISEASES OF THE BILIARY TRACT, SERIES #6
In certain cases where such a cut may be problematic,
such as in patients on anticoagulation, the endoscopist
may elect to balloon dilate the sphincter area. It should
be noted though that there are reports of higher risks of
post-ERCP pancreatitis in cases where balloon dilation
has been used (20). In cases where cannulation is difficult
to achieve, a needle knife papillotome can be used
in a technique known as “precutting” to establish direct
access into the bile duct. Once access is achieved, a
variety of instruments are available to attempt ductal
clearance. Most stones up to 15 mm in size can be
removed by sweeping the ducts with an extraction balloon,
or alternatively by using a Dormia basket provided
that a large enough sphincterotomy has been
performed (21). In certain instances, though, the stone
size may be too large to extract, and as such, alternative
methods such as lithotripsy should be considered.
Different lithotripsy modalities are available
including mechanical, electrohydraulic, laser and extracorporeal
shock wave (22,23). Mechanical lithotriptors
are widely available. They consist of a basket with two
sheaths: plastic and metal. Once the stone is caught in
the basket wires, the metal sheath is advanced over the
plastic sheath, and the stone is crushed into smaller
pieces against the metal. Mechanical lithotripsy has
high success rates but can be limited in the setting of
stone impaction (24). Most tertiary care centers have
the capability of performing intraductal lithotripsy
through the use of a SpyGlass ® choledochoscope
(Boston Scientific Corp, Natick, MA, USA), which
allows for direct visualization of the ductal lumen (25).
Laser lithotripsy amplifies light energy to break up the
stone, while the electrohydraulic method relies on
shock waves produced by a power generator and transmitted
through a bipolar electrode (22,26).
Under certain circumstances, only partial ductal
clearance is achieved, and a repeat ERCP is needed. In
such situations, it is typical to insert a temporary biliary
stent to secure ductal patency while the patient
awaits the second procedure (27). In most cases, the
ERCP can be performed on an outpatient basis and
does not require an overnight hospital stay unless early
post-procedure complications are suspected.
The readmission rates following biliary sphincterotomy
and same day discharge are approximately 6%,
with the majority of cases being readmitted for post-
ERCP pancreatitis. Readmission is more likely to occur
in patients who have one or more of the following risk
factors: suspected sphincter of Oddi dysfunction, cirrhosis,
difficult bile duct cannulation, precut sphincterotomy,
or combined percutaneous-endoscopic procedure.
The majority of complications requiring readmission
occur within six hours following the procedure (28).
PREVENTING RECURRENCE
Recurrent CBD stones occur most frequently in patients
with concurrent choledocholithiasis and cholelithiasis
(29). A study of 371 patients who underwent an ERCP
with sphincterotomy but who did not undergo subsequent
cholecystectomy over a span of 7.7 years found a
10% recurrence rate of choledocholithiasis (30). A
smaller study of 120 patients who had undergone a biliary
sphincterotomy for CBD stones and who were randomized
to laparoscopic cholecystectomy or a “wait
and see” policy found that recurrent biliary events were
observed more frequently over the next 2 years in the
watchful waiting group as compared to the treated group
(47% versus 2%, respectively) (31). It is therefore recommended
that an elective cholecystectomy be performed
as soon as possible following ductal clearance if
the patient is deemed to be a surgical candidate.
BILIARY STRICTURES
Biliary strictures can be benign or malignant. The general
approach to treatment is based on the need to reestablish
bile flow through the narrowed area in order
to avoid complications including biliary stasis, jaundice
and infections. A wide spectrum of clinical presentations
has been described with biliary strictures
ranging from asymptomatic patients with mild liver
function test abnormalities to full blown obstructive
jaundice, hyperbilirubinemia and recurrent episodes of
cholangitis. Many classifications have been generated
for biliary strictures. However, the Bismuth classification
is the most widely used. It subdivides strictures
into five groups depending on the stricture location
within the biliary tree (Table 1) (32).
Differentiating between benign and malignant etiologies
is of high clinical importance. A full discussion
about the clinical indices of possible malignancy is
beyond the scope of this review; however, certain ele-
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Diagnostic and Therapeutic Endoscopy of Biliary Diseases
DISEASES OF THE BILIARY TRACT, SERIES #6
Table 1.
Bismuth Classification
Stricture Type
Benign strictures
Type 1
Type 2
Type 3
Type 4
Type 5
Malignant Strictures
Type 1
Type 2
Type 3a
Type 3b
Type 4
Description
Low common bile duct stricture
>2 cm distal to the bifurcation
Mid common bile duct stricture
2 cm distal to the bifurcation
Mid common bile duct stricture

Diagnostic and Therapeutic Endoscopy of Biliary Diseases
DISEASES OF THE BILIARY TRACT, SERIES #6
(continued from page 34)
cytology improves the brushing’s diagnostic accuracy
(41). Targeted intraductal forceps biopsies through the
use of a cholangioscope can improve the sensitivity to as
high as 96% (42). The use of SpyGlass ® cholangioscopy
results in a sensitivity of 71% and specificity of 100% in
diagnosing malignancy in an indeterminate stricture
(43). IDUS is a relatively newer technique which can
better evaluate and distinguish between benign and
malignant lesions when coupled with ERCP, increasing
the diagnostic accuracy to up to 90% (14).
Image-enhanced cholangioscopy techniques
include chromocholangioscopy, autofluorescence imaging
(AFI) and narrow band imaging (NBI). These may
further enhance the ability to detect malignancies in
indeterminate lesions but have a limited availability and
require a high level of training (44). Confocal electromicroscopy
has been recently introduced as an additional
imaging modality. The miniprobe is used in
conjunction with a cholangioscope, and it allows for the
detection of specific vasculature patterns. The presence
of irregular vessels predict a neoplastic process with an
accuracy of 86%, a sensitivity of 83%, with a specificity
of 88%. Further investigative studies are ongoing to better
determine its future application (44–46).
Managing Malignant Strictures
Common etiologies of malignant biliary strictures
include pancreatic carcinoma, ampullary carcinoma,
cholangiocarcinoma, gallbladder cancer, hepatocellular
carcinoma and metastatic lesions. Once a malignancy
has been established, the focus switches to
determine the extent of the disease and its resectability.
Patients should be referred for surgical and oncologic
evaluation. Immediate relief of the obstruction should
be established if possible. The use of temporary plastic
stents is favored in patients who may be surgical
candidates or in cases where the diagnosis is unclear.
Self expanding metal stents (SEMS) are usually
reserved for patients with unresectable disease and a
life expectancy exceeding five to six months (47).
Special Patient Populations: Chronic
Pancreatitis, Primary Sclerosing
Cholangitis and Liver Transplant Recipients
Chronic pancreatitis related distal bile duct strictures
deserve special attention as they account for up to 10%
of all CBD strictures and carry a significant amount of
morbidity. Inflammation and fibrosis can make it difficult
to establish adequate access during an ERCP, and
endoscopic management can therefore be limited. Studies
suggest that the use of multiple stents may be superior
to single stents in this patient population. In cases
refractory to repeated stenting and endoscopic therapy,
surgery may be required and is usually complicated
because this patient population typically suffers from
comorbid conditions and additional complications such
as vascular thrombosis and liver involvement (43).
In patients with primary sclerosing cholangitis
(PSC), chronic inflammation leads to multiple fibrotic
strictures of the entire biliary tree and eventually results
in significant liver disease and cirrhosis (Figure 3).
Medical therapy has not proven to be of benefit, and the
use of ursodeoxycholic acid is no longer recommended.
Liver transplantation is the only long-term option for
Figure 2. Ischemic common bile duct stricture seen on
cholangiogram with dilation of the proximal bile duct.
Figure 3. Cholangiogram showing significant extrahepatic
(thick arrow) and intrahepatic (thinner arrows) structuring
consistent with primary sclerosing cholangitis.
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Diagnostic and Therapeutic Endoscopy of Biliary Diseases
DISEASES OF THE BILIARY TRACT, SERIES #6
severe cases. Dominant extrahepatic strictures are common
in PSC patients occurring in up to 50% of cases.
They may lead to cholangitis, which in turn can worsen
the extent of damage to the liver. Their presence is typically
suspected clinically based on worsening jaundice
and pruritis and increasing liver function test abnormalities.
It is important to rule out a malignant process in
these patients in view of the substantially increased risk
of cholangiocarcinoma (8%-14% of patients) (48).
Endoscopic therapy consists of dilation of the dominant
stricture and extraction of any stones or sludge that may
be lodged above the strictured area. Short-term stenting
may be effective in a small number of patients. However
stent occlusion remains a problem. Repeat dilations may
be required in many cases. Stenting after balloon dilation
may not have any additional benefit (49).
Anastomotic strictures are common post orthotopic
liver transplantation (OLT) with an incidence around
5%–10%. These typically are short segment strictures
and occur within one year of the transplant with early
strictures resulting from technical complications of the
surgery and later ones from vascular insufficiency and
fibrosis (50). Risk factors include tension at the anastomosis,
caliber mismatch between donor and recipient
ducts, and excessive use of electrocauterization for control
of intra-operative bleeding (51). Endoscopic management
with repeated dilation and stenting remains the
treatment of choice. Newer data suggest that the use of
fully covered metal stents may be beneficial in these
patients by spacing out the ERCPs needed and therefore
decreasing costs and associated risks (52).
BILE LEAKS
Bile leaks occur mainly as a complication of biliary
surgery, including laparoscopic cholecystectomy (up
to 1.1% of cases) and cadaveric OLT. The leak can
occur at the cystic duct stump or can involve the
smaller ducts of Luschka. The presentation is typically
acute within the first few days following surgery but
may be delayed with a few cases presenting up to one
month later. Imaging studies, such as an ultrasound or
CT scan of the abdomen, are usually diagnostic, but
the absence of a biloma on imaging does not exclude
the diagnosis. Endoscopic cholangiography can establish
the diagnosis in the vast majority of patients and
Figure 4. Cholangiogram showing extravasation of contrast
diagnostic of a bile leak in a patient with recent cholecystectomy.
can provide therapeutic means in the same setting (53).
Figure 4 shows a cholangiogram illustrating a bile leak
in a patient with a recent cholecystectomy.
The therapeutic goal is to establish an area of lower
resistance for the bile to flow through. This is usually
achieved by the insertion of a short temporary biliary
stent, therefore relieving the high transpapillary pressure
gradient. A biliary sphincterotomy may be enough
in certain milder cases. Response is typically measured
by the clinical improvement and decreased outputs
from percutaneous surgical drains. Stents are typically
left in place for about four to six weeks. Bile leaks
refractory to endoscopic treatment typically require
surgical interventions to correct the defect (54).
CONCLUSIONS
In summary, much progress has been made over recent
years in diagnosing and treating biliary tract disorders.
Endoscopic therapy has become the predominant
modality used in both the diagnosis and treatment of
these disorders. The future of therapeutic endoscopy
promises to be quite interesting as it continues to
evolve and offer more innovative new techniques. n
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