Plastic Biliary Stents for Benign Biliary Diseases

Biliary plastic stenting plays a key role in the endoscopic management of benign biliary diseases. Complications following surgery of the biliary tract and liver transplantation are amenable to endoscopic treatment by plastic stenting. Insertion of an increasing number of plastic stents is currently the method of choice to treat postoperative biliary strictures. Benign biliary strictures secondary to chronic pancreatitis or primary sclerosing cholangitis may benefit from plastic stenting in select cases. There is a role for plastic stent placement in nonoperative candidates with acute cholecystitis and in patients with irretrievable bile duct stones.

Plastic stents were the first endoprostheses used for the management of biliary disease. The first biliary stent placement was reported in the late seventies by Soehendra and Reynders-Frederix, for the palliation of a malignant biliary stricture.

Since then, biliary plastic stent placement has become a well-established technique for numerous indications. The procedure already has a universally recognized role in the management of malignant biliary obstruction, and biliary plastic stents are now gaining consensus for the treatment of a variety of benign biliary disorders. The spectrum of benign diseases amenable to endoscopic stenting has expanded in recent years and currently includes postoperative biliary injuries, including leaks and strictures, dominant biliary strictures in primary sclerosing cholangitis, chronic pancreatitis, cholecystitis, and large nonremovable biliary stones.

The outcomes of plastic stent placement for the management of benign biliary disorders are summarized in this review. Patient selection and indications for stent placement are discussed, and some technical hints for stent placement in the various clinical scenarios are provided.

Postoperative biliary injuries

Bile Duct Leak

Bile leaks are most often a consequence of surgery (open and laparoscopic cholecystectomy, liver transplantation, and major hepatic surgery) or trauma. Endoscopic treatment aims at reducing the pressure gradient between the biliary tree and the duodenum to promote preferential bile flow into the duodenum and allow the leak to seal. This outcome can be accomplished by biliary stenting, biliary sphincterotomy, nasobiliary drainage (NBD), or a combination of these techniques. These methods seem to be equally effective in facilitating closure of a biliary leak within a few days, and the endoscopic approach of choice remains controversial because each option has its own limitations and advantages.

Endoscopic sphincterotomy is associated with immediate, short-term, and long-term complications, but is necessary when dealing with associated residual common bile duct (CBD) stones.

Disadvantages in using NBD include prolonged hospitalization stays while awaiting leak closure, patient discomfort, and tube migration or inadvertent dislodgement. Its main advantage is maintenance of access for repeat cholangiography to confirm leak closure.

Stent placement requires at least 1 repeated procedure for stent removal, more if stent occlusion or migration occurs, but it avoids the need for sphincterotomy. Stents are necessary when a biliary stricture is located distal to a leak.

In an animal study, more rapid closure of a postcholecystectomy cystic duct leak was achieved with stent placement compared with biliary sphincterotomy alone. Endoscopic stent placement seems to be the preferred method of treatment of bile leaks at many centers. Although some advocate placement of a stent of sufficient length to traverse the site of the bile duct defect, traversing the papilla is often all that is necessary to optimize the pressure gradient for internalization of bile flow.

Nearly all postoperative biliary leaks, with the exception of complete transection of the CBD, which is an indication for reconstructive surgery, are amenable to endoscopic therapy. As early as 1991, Binmoeller and colleagues reported successful healing of biliary leaks in 82% of 77 patients treated endoscopically. These results have been confirmed and improved upon in more recent studies with a greater than 90% success rate in leak closure.

Sandha and colleagues proposed the use of biliary sphincterotomy alone to treat small leaks (visualized only after filling of the intrahepatic ducts) and temporary (4–6 weeks) biliary stenting for large leaks (visualized before intrahepatic duct opacification) or in the setting of associated strictures, contraindications to sphincterotomy or inadequate drainage of contrast medium after sphincterotomy. This approach led to leak closure in more than 90% of 207 consecutive patients.

Different stent strategies to manage biliary leaks (stenting with or without sphincterotomy, various stent sizes and stent duration) were proposed and compared, all with similar results. Mavrogiannis and colleagues compared 6 to 8 weeks of stent placement using either a 7 French stent without biliary sphincterotomy or a 10 French stent with biliary sphincterotomy, whereas other investigators compared 4-week stenting using either a 10 or 7 French stent (after biliary sphincterotomy).

Biliary stents have also been successfully used to reestablish the continuity of disrupted sectorial/segmental branches at the level of the main hepatic confluence and for leaks from aberrant bile ducts.

The use of large bore stents (>10 French) is preferred to avoid early clogging and to improve bile flow; stents are usually removed 4 to 8 weeks after insertion.

Postoperative Benign Biliary Strictures

Postoperative benign biliary strictures (POBS) occur most commonly after cholecystectomy and are often the result of direct surgical trauma related to partial or complete transection of the bile duct by clipping or ligation. Another mechanism for POBS development is an ischemic insult of the biliary wall caused by dissection or thermal injury.

POBS are usually diagnosed within 6 to 12 months from surgery, and patients may present with jaundice, recurrent cholangitis, abdominal pain, pruritus, bile duct stone formation, and even secondary biliary cirrhosis. Liver biochemistries usually show anicteric cholestasis. Careful evaluation by noninvasive imaging techniques (mainly magnetic resonance cholangio pancreatography [MRCP]) is advisable to plan the treatment strategy.

Bismuth and Lazorthes classified such benign strictures into 5 types:

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Type 1: common bile duct strictures located greater than or equal to 2 cm from the main hepatic confluence
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Type 2: common hepatic duct stricture located less than 2 cm from the main hepatic confluence
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Type 3: ceiling of the biliary confluence is intact, right and left ductal systems communicate
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Type 4: ceiling of the confluence is destroyed, bile ducts are separated
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Type 5: stricture of an isolated aberrant right duct.

When the stricture is close to the hilar confluence, endoscopic management becomes more challenging and needs to be adapted on a case-by-case basis according to the bile duct anatomy.

In a large series, surgical repair of POBS carried a mortality risk close to 2% and relevant morbidity up to 40%. Stricture of the bilio-digestive anastomosis is reported in 10% to 15% of cases after 4 to 10 years of follow-up, requiring reintervention or repeated percutaneous treatment for prolonged periods of time leading to an impaired quality of life.

Endoscopic treatment of POBS is preferred over percutaneous techniques because it avoids the risk of liver puncture and more easily accesses nondilated intrahepatic ducts. Also, the endoscopic approach is more comfortable for patients because it avoids the need for external drainage.

In the absence of complete transection or ligation of the bile duct, all patients with POBS are candidates for endoscopic treatment. Surgery can be undertaken in cases of failed endotherapy, whereas hepaticojejunostomy makes future endotherapy difficult, if not impossible.

Bergman and colleagues reported on the results of endoscopic stent therapy of POBS in 74 patients using the following protocol: insertion of two 10 French stents whenever possible, planned stent exchange every 3 months, and stent removal at 1 year (so-called Amsterdam protocol). However, because of a variety of reasons, only 59% (44 patients) of the original cohort completed the protocol. The patients were followed for a median time of 9.1 years. Strictures recurred in 20% of patients with the majority presenting within 6 months of stent removal (median 2.6 months, range 2 months to 15 years), potentially because of incomplete treatment. Major complications, including cholangitis, pancreatitis, bleeding, and stent migration, were more common in patients who were noncompliant with the stent exchange protocol.

A more aggressive approach was reported by the authors’ institution. At each exchange scheduled every 3 months, all previously placed stents were removed and the maximum number of large-diameter stents inserted, as permitted by the diameter of the duct distal to the stricture and the tightness of the stricture itself. The treatment protocol was stopped when complete morphologic disappearance of the stricture was demonstrated by occlusion cholangiography after stent removal. Complete disappearance of the stricture was defined as absence of any significant indentation at the site of previous narrowing. Of 45 patients, 42 completed the protocol. When compared with the Amsterdam protocol, there was no increase in early and delayed complication rates. Complete morphologic disappearance of the stricture was obtained in 40 patients (89%), with a mean number of 3.2 ± 1.3 stents (range: 1–6) for a mean treatment duration of 12.1 ± 5.3 months (range: 2–24 months). Two patients died of unrelated causes. The remaining patients were followed for a mean of 4 years without evidence of stricture recurrence and there was 1 case (2.5%) of cholangitis caused by biliary sludge, retreated endoscopically.

These promising results were recently confirmed in the same cohort after a long follow-up (mean 13.7 years, range 11.7–19.8) with a 11.4% stricture recurrence rate, all successfully retreated endoscopically.

Satisfactory results have also been reproduced in a prospective trial involving 43 patients with postlaparoscopic cholecystectomy bile duct strictures in whom a similar aggressive protocol for endoscopic stenting was followed. A mean of 3.4 ± 0.6 (range 3–5) stents were placed for a period of 1 year. The investigators reported a 100% success rate for stricture dilatation with no stricture recurrence at a mean follow up of 16.0 ± 11.1 (range 1–42) months after stent removal.

The major drawback of placement of multiple plastic stents for POBS is the need for repeat endoscopic retrograde cholangiopancreatographies (ERCPs), frequent stent exchanges, and the risk of cholangitis caused by stent dislodgement or poor patient compliance with scheduled stent exchanges.

Endoscopic treatment of POBS needs to be carefully explained to patients and undertaken in those who are willing to accept the 3-monthly stent-exchange schedule. A recall system, especially for patients who are noncompliant, is necessary to prevent cholangitis.

The following are key points and tips for placement of multiple plastic stents in POBS:

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Use of magnetic resonance cholangiography (MRC) as a roadmap for planning treatment
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Biliary sphincterotomy to facilitate placement of multiple plastic stents
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Balloon dilation of strictures to 6 to 8 mm diameter depending on the size of the bile ducts above the stricture
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Measurement of the distance between the stricture and the papilla using a catheter with radiopaque markers to select the proper stent length
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Placement of the maximum number of stents (possibly 10 French) in relation to the severity of the stricture and diameter of the bile duct proximal and distal to the stricture
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Use of angled hydrophilic guidewires to negotiate strictures and pass into intrahepatic ducts to position the catheter where the proximal end of the stent will reside
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Exchange to stiff guidewires
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Use of preshaped Cremer hilar stents or a 12-cm long Cotton-Huibregtse (duodenal bend) stent (Cook Endoscopy, Winston Salem, NC, USA) placed upside down (especially when placed into the left hepatic duct) ( Fig. 1 )

Fig. 1

Multiple stent placements for CBD stricture after cholecystectomy. ( A ) Bismuth type II (<2 cm from the hilar confluence) postoperative bile duct stricture following laparoscopic cholecystectomy, ( B ) balloon dilation, and ( C ) insertion of 2 plastic stents. ( D ) Three months later, stricture improved and ( E ) 5 stents (10 F diameter) were inserted. ( F ) At planned reevaluation, 3 stents had migrated distal to the stricture; ( G ) 5 stents were reinserted (4 in an upside-down position in the left hepatic duct); and ( H ) stents were in place 3 months later, and the stricture completely resolved. ( I ) A Cotton-Huibregtse 12-cm-long stent in upside-down position ( left ) and Cremer hilar stent ( right ).
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Stent exchange every 3 months to minimize the risk of stent occlusion-related cholangitis
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Avoidance of balloon dilation (unless necessary) of the stricture during stent exchanges to reduce trauma to the bile duct
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Increase the number or the diameter of stents at each stent exchange
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Treatment duration (stents in place) for at least 12 months
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Stent removal after complete disappearance of the stricture as visualized by balloon occlusion cholangiography
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Close clinical and laboratory follow-up (liver function tests obtained every 3 months for the first years then every 6 months) after stent removal to allow for early detection of stricture recurrence.

Endoscopic management of POBS is considered the first-line treatment for most instances. An aggressive approach placing multiple stents improves results and is the strategy of choice. Surgical reconstruction should be considered for complete transection of the bile duct when endotherapy fails or to treat recurrent strictures.

Biliary Strictures After Liver Transplantation

Endoscopic plastic stent placement is now considered the first-line therapy for biliary strictures that occur after orthotopic liver transplantation (OLT) and living-donor liver transplantation (LDLT).

Biliary strictures occurring after OLT were traditionally managed by surgical repair or balloon dilation, with or without stent insertion, by means of the percutaneous transhepatic route. As data accrued on successful management of POBS, ERCP and endoscopic biliary plastic stent placement became the primary therapeutic approach for anastomotic strictures after liver transplantation.

Despite the improvements in surgical technique, organ selection, procurement, and preservation, complications of the biliary tract after liver transplantation remain frequent. Strictures account for about 40% of these complications and occur in about 5% to 15% of deceased-donor OLT and 30% of right-lobe LDLT.

Biliary strictures after OLT are classified into 2 main types: anastomotic and nonanastomotic. The incidence, etiology and pathogenesis, presentation, natural history, prognosis, and response to therapy with stent placement differ between the 2 types.

Anastomotic strictures may occur with any biliary anastomosis, whether duct-to-duct or hepaticojejunostomy, in deceased- or living-donor OLT. They are usually solitary strictures and respond favorably to dilation. Anastomotic strictures are the result of improper surgical techniques (excessive use of electrocoagulation, tension at the level of the anastomosis, inappropriate bile duct dissection), small-caliber bile ducts, localized ischemia, infections, or fibrotic healing.

Nonanastomotic strictures (NAS) may occur anywhere in the biliary tree, either at the level of the hilum, the extrahepatic, or the intrahepatic ducts. They account for 10% to 25% of strictures after OLT. NAS are often multiple, longer than anastomotic strictures, and occur earlier in the postoperative period. Biliary sludge and casts are often associated with nonanastomotic strictures, which are notably difficult to treat and poorly responsive to dilation and nonoperative treatments. Multiple factors contribute to the occurrence of NAS, including ischemia-related injuries, ABO incompatibility, hepatic artery thrombosis (in up to 50% of cases), and immunologic injury to the biliary epithelium. A prolonged cold ischemia time in cadaver donor OLT was significantly associated with the occurrence of NAS.

Therefore, differentiation of anastomotic and nonanastomotic strictures is clinically important.

Some prerequisites fundamental and necessary for successful endoscopic plastic stent placement after OLT include duct-to-duct biliary reconstruction and accessibility of the papilla of Vater. Despite case series, endoscopic treatment of biliary strictures in patients with Roux-en-Y hepaticojejunostomy is difficult and challenging. Either a colonoscope or balloon enteroscope is needed to reach the anastomotic site.

Although the technique of endoscopic plastic stent placement is well defined and now standardized, there is variability in the treatment of post-OLT biliary strictures based upon review of published studies. Differences include the diameter of stents, diameter of dilating balloons used, the number of side-to-side stents placed, the number of balloon dilations or stent exchanges performed, the time interval between stent exchange, and the overall duration of stent placement. These differences are likely responsible for the large variation in observed outcomes.

Anastomotic strictures

Balloon dilation of anastomotic biliary strictures without stent placement is successful in less than 50% of cases.

In a retrospective study of 25 patients with biliary anastomotic strictures, it was found that despite similar immediate success rates, clinically relevant stricture recurrences are more frequent in patients treated with balloon dilation only (recurrence 62%) than in those treated with dilation and stent placement (recurrence 27%). Other investigators have found that a one-time stricture dilation session was effective in only 31.0% of patients, whereas 34.4% of patients required more than 1 balloon dilation session and another one-third required subsequent stent placement. Schwartz and colleagues used small-caliber balloons (4–6 mm) and found balloon dilation alone to be effective in 47% of patients. In a randomized trial that compared balloon dilation alone with balloon dilation and stent placement, dilation alone was as effective as stent placement (sustained clinical success 71% vs 73%). The study was performed on a limited number of patients (n = 32), which included 6 patients with nonanastomotic strictures and 3 with hilar strictures (who had the worst long-term prognosis). Furthermore, in the stent group, patients were usually treated only with the simultaneous placement of few stents (starting with 1 stent, and increasing to a maximum of 3 stents), which may have affected the long-term success rate in the stent group.

Some patients may only have a transient narrowing of a duct-to-duct anastomosis within the first 30 to 60 days after OLT caused by acute edema and inflammation. These strictures respond well to a single session of balloon dilation or placement of a single stent. However, in the vast majority of post-OLT anastomotic strictures, a large-caliber (>6 mm) balloon dilation followed by placement of multiple stents placed side to side appears to be more successful with a durable outcome and is the current preferred approach for the management of anastomotic strictures.

Stent placement for anastomotic strictures is easy when the liver has been transplanted from a deceased donor because the biliary anastomosis is usually located at the level of the middle common bile duct, far from the main biliary confluence.

The technique of placement of multiple plastic stents has been previously described (see POBS section). A distinction of post-OLT biliary strictures, also seen in tight strictures, is that the transplanted liver bile ducts do not display the same degree of proportional dilation as nontransplanted livers. This peculiar behavior has not been completely clarified; however, the presence of fibrosis leading to less pliable ducts has been suggested as a possible etiology. Nevertheless, the absence of substantial dilation of the bile ducts may limit the number of stents that can be placed side to side for the initial stricture dilation.

Large bore stents, 10 or 11.5 French polyethylene stents, are preferred. Standard Cotton-Leung stents (Amsterdam type, central bend) or Cotton-Huibregtse (Cook Endoscopy, Winston Salem, NC, USA) (duodenal bend) stents are chosen for the management of post-OLT anastomotic biliary strictures; they are inexpensive, widely available, available in different calibers and lengths, can be easily tailored or shaped if necessary, and remain patent for a mean of 3 to 4 months. There are isolated reports on the use of inside stents (modified polyethylene endoprostheses that have been placed completely inside the bile ducts, above the papilla of Vater, in an attempt to prolong patency and to reduce the risk of ascending cholangitis). The benefits of such stents have not been demonstrated in controlled trials.

The majority of patients with anastomotic biliary strictures that occur after deceased-donor transplantation require several endoscopic interventions (on average between 1.6 and 6.0), with successful long-term clinical and morphologic resolution of the stricture between 70% and 100%. Recurrences have been variably reported in approximately 0% to 20% of cases, but can usually be managed conservatively by repeat endoscopic stent placment. The major disadvantages of endoscopic dilation of anastomotic strictures with plastic stents include the need for multiple procedures repeated over an extended period of time and the risk of cholangitis resulting from stent occlusion. A protocol of accelerated dilation, with plastic stent exchange every 2 weeks and an overall shortened stent period of an average of 3.6 months, showed an 87% success rate.

Patients with anastomotic strictures after OLT require long-term surveillance because strictures may recur, even years after stent removal. Long-term surveillance by liver function test monitoring and noninvasive imaging is advisable. Some investigators have observed that anastomotic strictures that are diagnosed within 6 months after OLT have a better prognosis and response to endoscopic therapy.

Nonanastomotic strictures

In contrast to anastomotic strictures, the management of nonanastomotic strictures after OLT should be individualized. Because of their complex etiology and pathogenesis, nonanastomotic strictures respond less predictably to endoscopic stent placement. Sludge, debris, and casts are commonly found in these patients and may cause early stent occlusion and recurrent cholangitis.

Stent placement for nonanastomotic strictures is technically demanding and cumbersome. These strictures are usually multiple and variably extend from the proximal common bile duct to the main biliary confluence and sometimes into the intrahepatic branches ( Fig. 2 ).