Infections of the Biliary Tract

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Chapter 45 Infections of the Biliary Tract

imageVideo related to this chapter’s topics: Biliary Tract Infections–Worms

Introduction

The histologic definition of cholangitis is inflammation of the bile duct. However, when used in practice, cholangitis refers to a characteristic clinical presentation associated with bile duct obstruction and bacterial infection. Other etiologies of bile duct inflammation have a preceding descriptor (e.g., parasitic cholangitis). All types of bile duct inflammation may be complicated by obstruction and secondary bacterial infection. The conditions predisposing to cholangitis are listed in Box 45.1.

Bacterial cholangitis accounts for most infections of the biliary tract. The underlying cause is usually extrahepatic bile duct obstruction from a stone or stricture and is readily managed by medical and endoscopic therapy. Less common forms of infectious cholangitis include recurrent pyogenic cholangitis, parasitic cholangitis, and acquired immunodeficiency syndrome (AIDS) cholangiopathy. Recurrent pyogenic cholangitis results from obstruction of the intrahepatic and extrahepatic biliary tract with repetitive episodes of bacterial cholangitis and is seen almost exclusively in Eastern Asia. Elsewhere in the world, patients with this condition present de novo or after emigration. Parasitic cholangitis affects individuals residing in areas endemic with pathogens that infest the biliary tract. AIDS cholangiopathy is characterized by typical abnormalities on cholangiography combined with parasitic or viral infection of the biliary tract. Both parasitic cholangitis and AIDS cholangiopathy may be complicated by secondary bacterial cholangitis.

Cholecystitis usually results from obstruction of bile flow at the level of the cystic duct with subsequent mucosal inflammation of the gallbladder. Similar to cholangitis, migrated gallstones are the underlying etiology of most cases of cholecystitis. Acalculous cholecystitis is due to cystic duct obstruction from another cause or occurs in the absence of obstruction. Infection of the gallbladder is a common complication of cholecystitis but is rarely the underlying cause. Although the treatment of cholecystitis is usually surgical, there is emerging endoscopic experience in patients who are not surgical candidates.

Endoscopic Retrograde Cholangiopancreatography

Complications

Complications of ERCP include the complications inherent to any endoscopic procedure, including reactions to medications, cardiopulmonary complications, infection, perforation, and hemorrhage, and complications specific to ERCP, such as pancreatitis, postsphincterotomy hemorrhage, and biliary infection. Infectious complications of ERCP are post-ERCP cholangitis and long-term postsphincterotomy cholangitis. The rate of complications related to ERCP is 5% to 8%; risk of complications related to ERCP is 0.3%.4,5

Post–Endoscopic Retrograde Cholangiopancreatography Cholangitis

The risk of cholangitis immediately after ERCP is very low—0.7% in a large series from a single referral center where drainage of obstructed ducts is practiced aggressively.6 The incidence of cholangitis increases 10-fold if diagnostic ERCP is undertaken without performing biliary drainage when an obstruction is found.7 This increased incidence is due to contaminating sterile bile with enteric bacteria, which in the presence of obstruction results in cholangitis. Any obstructed segment of the biliary tract opacified during cholangiography should be drained. Improper disinfection of duodenoscopes or use of contaminated water also increases the risk of post-ERCP cholangitis and bacteremia, especially with Pseudomonas aeruginosa.8,9

Long-Term Postsphincterotomy Cholangitis

Surgical or endoscopic sphincterotomy is a risk factor for bacterial contamination of the biliary tract,10 likely by facilitating transpapillary migration of enteric bacteria. Escherichia coli is the most common organism identified. Analysis of patients after cholecystectomy who underwent sphincterotomy revealed a predisposition for developing brown stones or sludge within the common bile duct (CBD) in association with bacteriobilia.11 However, these data may be biased by predilection in choledocholithiasis prompting sphincterotomy in the first place.

Cholangitis

Bacterial cholangitis results from bile duct obstruction or previous biliary instrumentation. Enterobacteriaceae are the most common causative organisms, and blood cultures are positive in 50% of patients.12 Isolation of enterococci or multiple organisms from bile is more common in patients with a biliary endoprosthesis13 or bilioenteric anastomosis. Charcot’s triad of right upper quadrant pain, fever, and jaundice is present in 70% of patients with acute bacterial cholangitis. The addition of hypotension and confusion constitutes Reynolds’ pentad, which is present in less than 5% of patients with cholangitis but is significantly associated with mortality.14 Right upper quadrant pain and fever may be absent in elderly patients, diabetic patients, or patients treated with systemic corticosteroids.

Preparation

Prophylactic antibiotics are not recommended routinely in patients with biliary obstruction undergoing ERCP for prevention of endocarditis or post-ERCP cholangitis.19,20 However, in patients with cholangitis, broad-spectrum antibiotics providing coverage of gram-negative bacilli and Enterococcus species are indicated until biliary drainage is successfully completed.

Procedure

Outcomes

Treatment of acute cholangitis includes resuscitation, antimicrobials, and biliary tract drainage (Fig. 45.2). Management of respiratory and circulatory insufficiency in a monitored setting and administration of broad-spectrum antibiotics should precede, but not delay, definitive biliary tract decompression in a severely ill or deteriorating patient.

Calculous Cholangitis

Biliary drainage can be accomplished endoscopically, percutaneously, or surgically. Endoscopic treatment, either sphincterotomy with stone extraction21,22 or biliary stent or nasobiliary drain insertion, is superior to surgical treatment in patients with severe cholangitis. Endoscopic sphincterotomy with stone extraction resulted in increased survival compared with surgery in a retrospective cohort of patients with acute calculous cholangitis21; this was despite a higher number of concomitant medical problems and increased age in the patients managed endoscopically. Lai and colleagues23 randomly assigned 82 patients with calculous cholangitis requiring emergent therapy to surgery or ERCP with nasobiliary catheter placement. The mortality in the surgical arm was significantly higher than in the endoscopic arm—32% and 10%. In addition, there were an increased number of nonfatal complications in the group undergoing surgery.

Sphincterotomy and stone extraction is usually attempted during the initial ERCP. However, in critically ill patients with acute cholangitis secondary to choledocholithiasis, it may be prudent to achieve biliary drainage endoscopically, by insertion of a stent or nasobiliary catheter, and defer stone extraction to a later time. Therapeutic response, procedure-related complications, and length of procedure are similar for biliary stents and nasobiliary catheters, but inadvertent catheter removal and patient discomfort are greater in patients who receive a nasobiliary catheter.24 Approximately 10% of patients have cholangitis owing to stones that cannot be removed by standard means, including mechanical lithotripsy. These stones include large stones, stones located proximal to a stricture, or stones greater than the diameter of the distal bile duct. Options are endoscopic EHL, extracorporeal shock wave lithotripsy, endoscopic laser lithotripsy, and permanent biliary stent placement.2527 Increasingly, the use of adjunctive biliary balloon sphincteroplasty is being used to remove CBD stones safely and effectively. An occlusion cholangiogram at completion of ERCP may ensure clearance but carries a significant risk of bacteremia in this situation.

If all stones or stone fragments cannot be removed during the initial endoscopic session, a stent should be left in place to provide bile drainage and prevent further cholangitis (Fig. 45.3). Long-term stent therapy is no longer advisable because of the high incidence of cholangitis and related deaths.28,29 Similar techniques can be employed in the cystic duct to treat Mirizzi’s syndrome.26,30,31 In a patient with cholangitis and gallstones but no evidence of choledocholithiasis on cholangiography, empiric endoscopic sphincterotomy does not appear to decrease the risk of subsequent episodes of cholangitis and results in a higher ERCP complication rate.32

Cholangitis Secondary to Stent Occlusion

Plastic biliary stents develop a bacterial biofilm on their surface,34 which leads to stent occlusion and risk of cholangitis. Uncovered self-expandable metal stents, by virtue of their larger diameter and composition, do not develop encrustation at the same rate and have a longer patency.34 If metal stent obstruction does occur, it is usually the result of tumor ingrowth between the metal struts or tumor overgrowth at either end. Metal stents covered with a synthetic coating to prevent tumor ingrowth seem to have a similar or increased duration of patency (Fig. 45.4).35

Recurrent Pyogenic Cholangitis

Recurrent pyogenic cholangitis, also known as Oriental cholangiohepatitis, is a clinical syndrome comprising repetitive episodes of bacterial cholangitis resulting from intrahepatic biliary obstruction with calcium bilirubinate stones or strictures or both. The bile ducts in the left lateral segment of the liver are often the only ducts affected or the most severely affected. This segment may be anatomically predisposed to stasis because of duct angulations slowing bile drainage. Chronic obstruction eventually causes permanent dilation of the proximal biliary tract, often filled with intrahepatic stones. Bile stasis and bacterial contamination may result in the development of multiple hepatic abscesses. Enterobacteriaceae bacteria are the most frequent organisms cultured from bile. P. aeruginosa may be seen in patients who have previously undergone endoscopic or surgical biliary intervention. Anaerobes are less common. Growth of multiple organisms, although unusual in other causes of cholangitis, often occurs in recurrent pyogenic cholangitis.36 Isolation of biliary parasites in patients with recurrent pyogenic cholangitis is common,37,38 but it is unclear whether the parasite is an etiologic agent or an incidental finding.

Preparation

Prophylactic antibiotics have been recommended to decrease the risk of cholangitis during ERCP in patients with recurrent pyogenic cholangitis.39 Magnetic resonance (MR) cholangiography before ERCP should be considered. The major advantage of MR cholangiography is complete visualization of the biliary tract including segments obstructed by calculi or strictures40 that may not be apparent by ERCP. Detailed knowledge of intrahepatic segment anatomy is necessary to correlate MR imaging to the opacified ducts at ERCP and guide endoscopic management.

Procedure

Cholangiography during ERCP also accurately documents duct dilation, intraductal stones, and gallstones (Fig. 45.5). The intrahepatic ducts appear straightened and acutely angulated at branches, likely secondary to periductal fibrosis. There is often distinct tapering of the intrahepatic ducts proximally, described as the “arrowhead” sign, and decreased duct branching. Complete occlusion of an intrahepatic duct by a stone may be represented by segmental absence of contrast material and is better assessed by MR cholangiography.

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