Bile duct stricture is a challenging clinical condition that requires a coordinated multidisciplinary approach involving gastroenterologists, radiologists, and surgical specialists. These biliary strictures can be categorized according to the nature of their etiology, which can be benign or malignant. Malignant strictures are usually the result of either a primary bile duct cancer, such as a cholangiocarcinoma (CCA) causing bile duct lumen narrowing and obstructing bile flow, or extrinsic compression of bile ducts by the surrounding lymph nodes or neoplasms of adjacent organs, namely the gallbladder, pancreas, or liver. Painless obstructive jaundice is a usual manifestation of malignant biliary strictures. The most common cause of malignant distal biliary obstruction is pancreatic cancer, and 70% to 90% of these patients develop jaundice during the course of their disease.1 Because of bile flow obstruction, the presence of toxic substances can result in multiple physiological disturbances. These distorted physiologic mechanisms can result in kidney failure, cardiac dysfunction, liver injury, hemostatic abnormalities, and altered body immunity.2 Hence, palliation of jaundice improves the general health of the patient and surgical outcomes and has made this therapeutic aspect promising. We review the therapeutic options for malignant biliary obstruction and discuss the role of self-expanding metallic stents (SEMS) for preoperative biliary drainage (PBD).

Operative removal of cancers causing malignant biliary strictures is currently the curative treatment of choice. However, these treatments are typically major operations associated with high morbidity.2 The concept is that preoperative reduction of serum bilirubin would reduce postoperative complications. Preoperative drainage might also favorably influence sepsis, endotoxemia, and intravascular coagulation.3 Such drainage can be achieved endoscopically, surgically, or percutaneously. Endoscopic retrograde cholangiopancreatography (ERCP) with biliary drainage has become the standard practice for treating this type of obstructive jaundice. In resectable cancers, preoperative drainage should be based on multiple factors:

1) The period of time from clinical presentation to anticipated surgery. If a patient undergoes pancreaticoduodenectomy within a few days of presentation and is a candidate for surgery, no instrumentation is preferable before surgery.

2) The presence of an urgent indication for biliary drainage, namely cholangitis, severe pruritus, or severe obstruction with very high bilirubin levels.

3) The adequacy of staging prior to ERCP. In some patients, adequate staging may not be possible and a stent placement may be preferred prior to laparotomy.

4) The functional status of the patient. Many patients are in poor nutritional status because of obstructive jaundice, which could improve following PBD.

5) The plan for neoadjuvant chemoradiation for locally advanced or borderline resectable pancreatic cancer when drainage in this setting would prevent hepatotoxicity from chemotherapeutic agents.4

PBD for obstructive malignant biliary strictures can be achieved via a percutaneous method, ERCP, or surgical bypass. Placement of a drainage system such as stents by means of the endoscopic route gained tremendous popularity because of its advantages of being least invasive and "easier to do" with fewer complications. Despite multiple reports of increased cost effectiveness,5 higher technical success, better biliary decompression, and less recurrent cholangitis6 when compared with endoscopic drainage, the percutaneous method is still not as popular as endoscopic drainage because of its perceived disadvantages such as the risk of liver puncture-related hemorrhage, difficult-to-manage drainage system, cutaneous infection, etc. Above all, the most feared complication as reported by Takahashi et al.7 was a 5.2% percutaneous transhepatic biliary drainage catheter tract recurrence, a figure that is not negligible when considering the ensuing curative surgery. In another earlier drainage study, Speer et al.8 revealed that patients randomized to the endoscopic method had a significantly higher success rate for jaundice relief (81% vs. 61%, p=0.017) and significantly lower 30-day mortality (15% vs. 33%, p=0.016) compared to those in the percutaneous group. The higher mortality after percutaneous stenting was related to complications associated with liver puncture, which were hemorrhage and bile leaks.8

The first description of drainage via ERCP was by Cotton at the Middlesex group who subsequently performed several studies that showed superiority with respect to palliation of jaundice and decreased complications compared to percutaneous drainage and surgical bypass. In this study, the stented patients had lower procedure-related mortality (3% vs. 14%, p=0.01), lower major complication rates (11% vs. 29%, p=0.02), and shorter median total hospital stays (20 days vs. 26 days, p=0.001). Conversely, recurrent jaundice occurred in 36 stented patients and 2 surgical patients. Late gastric outlet obstruction occurred in 17% of stented patients and 7% of the surgical group. Despite the early benefits of stenting, there was no significant difference in overall survival between the two groups (median survival: surgical, 26 weeks; stented, 21 weeks; p=0.065).8,9 In a subsequent meta-analysis in 2006, Moss et al.10 came to the same conclusion, i.e., endoscopic decompression via plastic stenting carried a lower risk of complications (relative risk [RR], 0.60; 95% confidence interval [CI], 0.45 to 0.81) but a higher risk of recurrent biliary obstruction (RR, 18.59; 95% CI, 5.33 to 64.86) when compared with traditional surgical bypass.

Other areas of concern are stricture location and choice of drainage endoprostheses. For strictures that are located proximally (high-grade hilar stricture), drainage has been associated with increased morbidity to the patient, especially sepsis, most particularly with increased rates of cholangitis. The choice between a plastic or metallic stent traditionally depends on the expected survival duration in those with unresectable tumors. However, in those with resectable tumors, the preoperative waiting period seems to be the most important factor influencing the decision for PBD and subsequent choice of drainage endoprostheses. The outcomes with SEMS have been superior to plastic stenting because of the increased SEMS patency and the ability to provide rapid biliary decompression from the larger lumens.11,12,13,14 However, the concern with SEMS placement is the provocation of an inflammatory and fibrotic reaction around the area of stent placement, making subsequent surgical dissection more difficult.15,16 Placement of such stents for biliary drainage before surgery has been a subject of great debate and controversy.

SEMS have been widely used for palliation of obstructive jaundice in patients with unresectable pancreaticobiliary cancers or those with locally advanced and metastatic cancers. Nevertheless, SEMS are increasingly being recognized for use in patients with resectable cancers or benign biliary strictures. 11,12,25,26,27,28,29

Most of these reports are retrospective studies that demonstrated the utility of SEMS for preoperative biliary decompression in patients with resectable or borderline resectable tumors. In a 5-year retrospective review of 241 pancreatic cancer cases, Siddiqui et al.28 found metallic biliary stents to be safe and effective for biliary drainage in patients with resectable cancer before undergoing pancreaticoduodenectomy and those receiving neoadjuvant therapy. They also determined the median time from stent placement to surgery in patients with operable pancreatic cancer, which was 4 weeks, a relatively long period of time for most patients to proceed without some form of biliary decompression. This potential delay was predominantly a result of medical optimization of patient comorbidities before surgery. This further reinforces the argument that metal stents should be considered for patients with resectable pancreatic cancer, especially if surgery is not immediately contemplated. Also, SEMS provide sustained palliation for patients with unresectable tumors with a low incidence of serious adverse events. A considerable number of patients never underwent definitive surgery, and SEMS in these patients served as palliative devices. During surgery, SEMS did not interfere or pose any technical difficulty. The complication rate was low at <10%, and complications were mostly minor.28 In a retrospective evaluation of operable hilar CCA, Grunhagen et al.26 revealed that SEMS provided rapid biliary decompression because of the wider lumen, making proximal sepsis less likely. Also, no endoscopic reinterventions were performed in these series, and rapid decompression enabled the patients to recover immediately; therefore, the interval between biliary decompression and explorative laparotomy was relatively short.26 In another review, Singal et al.29 showed that SEMS provided excellent patency with cholangitis occurring in <5% of cases, did not affect surgical technique, resulted in few postoperative complications, and was effective for patients receiving preoperative chemoradiation awaiting surgery. Overall, all of these studies allay the fear that endoscopically placed SEMS as part of PBD may interfere with subsequent surgeries. It is interesting to note that no special preferences in SEMS type were observed.25,28,29 These studies were, however, limited by their retrospective design and lack of a comparative group (Table 1).

Preoperative relief of biliary obstruction and palliation of jaundice are crucial and at the same time beneficial to those patients in whom early surgery is not feasible. This generally improves health and surgical outcomes. There are still conflicting issues about preoperative drainage resulting in increased morbidity and complication rates; hence, PBD is not recommended when early surgery is planned. On the other hand, its advantages are clearly seen in situations such as cholangitis, severe hepatic dysfunction, delay in surgery, need for neoadjuvant chemotherapy, and specific indications such as patients with hilar CCA undergoing right hepatic resection. The location of the biliary obstruction is important to the technical success of drainage and should be taken into consideration when deciding on PBD and subsequently on the method of PBD and the choice of biliary endoprostheses. The utility of a better SEMS with a wider lumen may somehow change the outcome of PBD dramatically, as shown in the previously discussed studies that indicated its advantages in providing rapid biliary decompression and significant reduction in preoperative reintervention rates when compared to a plastic stent. Furthermore, it did not interfere with subsequent surgery in many studies. However, further prospective randomized controlled studies are necessary to demonstrate the efficacy of SEMS in PBD, as most of the studies presented thus far are retrospective in design.