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Management of Malignant Biliary Tract Obstruction
Malignant bile duct obstruction (MBDO) occurs when tumor within or adjacent to bile ducts impedes the normal passage of bile from the liver to the intestinal tract. Tumors of pancreobiliary origin, such as cholangiocarcinoma and gallbladder and pancreas cancer, are the most common causes of MBDO. Other etiologies include lymphoma and metastases from any primary neoplasm. Many benign conditions may also cause biliary obstruction. Differentiation of benign and malignant causes of bile duct obstruction is essential because treatments are different.
Obstruction of the biliary tree blocks the normal pathway for bile excretion, resulting in cholestasis (Greek chole , “bile,” + stasis , “standing still”). This leads to measurable biochemical derangements including elevation in serum bilirubin (conjugated hyperbilirubinemia), γ-glutamyl transpeptidase, and alkaline phosphatase. Physical signs and symptoms are often present, and many are explained by the absence of bile in the intestinal tract or the appearance of bilirubin and bile salts in the serum. The presence of one or more of these signs and symptoms of obstructive jaundice usually prompts referral for biliary drainage.
Jaundice , a yellowish discoloration of tissues caused by the deposition of bilirubin, may be first detected as scleral icterus when the total serum bilirubin level exceeds 2 to 3 mg/dL. Darkening of the urine ( bilirubinuria ) occurs with renal excretion of conjugated bilirubin. Light-colored ( acholic ) stool is observed because of the absence of pigmented bilirubin breakdown products in the intestinal tract. Pruritus , a well-known but poorly understood symptom of cholestasis, is thought to be mediated by bile salt retention. Patients with jaundice may also experience constitutional symptoms including anorexia, nausea, and fatigue. Infection of obstructed bile ducts, termed cholangitis , is a clinical syndrome of broad spectrum ranging from low-grade fever to septic shock. Charcot described the triad of right upper quadrant pain, fever, and jaundice for diagnosis of cholangitis. Although cholangitis is relatively uncommon in MBDO when there has been no prior intervention to contaminate the biliary tree, it remains an important diagnostic consideration whenever a patient with biliary obstruction has fever.
Modern imaging capabilities permit robust noninvasive evaluation of the obstructed biliary tree. Regardless of which imaging modality is employed, certain observations about the pattern of biliary obstruction must be made. Chief among these observations is description of the point (or points) of biliary obstruction in anatomic terms. This can be accomplished by tracing dilated bile ducts as they pass from the periphery of the liver to the liver hilus and subsequently to the intestine, recognizing points of obstruction as sites where there is interruption or narrowing of dilated bile ducts. This is important because it facilitates preprocedural prediction of the cholangiogram so an optimal drainage procedure can be planned. Another key observation is evaluation of the patency of the portal vein and its intrahepatic branches. This is important because portal vein occlusion leads to atrophy of liver parenchyma, and drainage of atrophic liver segments will not result in recovery of liver function.
Sonographic examination is a common starting point in the imaging assessment, although overlying bowel gas can limit evaluation of the extrahepatic bile duct. Computed tomography (CT) and magnetic resonance imaging, including magnetic resonance cholangiopancreatography, offer powerful cross-sectional and multiplanar anatomic methods to evaluate the biliary tree and surrounding structures. With this armamentarium of noninvasive imaging tests, it is now unusual to require diagnostic percutaneous cholangiography (PTC) for evaluation of MBDO.
Endoscopic retrograde cholangiopancreatography and biliary drainage are often preferred over percutaneous approaches in centers where skilled endoscopists offer this service. For patients with low bile duct obstruction (obstruction of the common bile duct or common hepatic duct not involving the biliary confluence), endoscopic techniques permit diagnosis and therapy without the need for percutaneous approaches or exteriorized drainage catheters. High bile duct obstruction (obstruction proximal to or involving the confluence of left and right hepatic ducts) is better managed percutaneously by interventional radiologists. A percutaneous approach is also appropriate for patients in whom endoscopic retrograde biliary drainage is either not possible (e.g. prior pancreaticoduodenectomy) or unsuccessful. Interventional radiologic procedures used in the management of MBDO include PTC, percutaneous transhepatic biliary drainage (PTBD), stent placement, and bile duct biopsy.
Indications
The indication for biliary intervention typically includes imaging evidence of biliary obstruction plus the need for diagnosis or treatment of one or more of the clinical manifestations associated with MBDO.
Percutaneous Transhepatic Cholangiography
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As the initial step in PTBD.
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For anatomic depiction of the pattern and extent of biliary obstruction when attempts to obtain this information noninvasively have either failed or been inconclusive.
Percutaneous Transhepatic Biliary Drainage
In the presence of MBDO when endoscopic retrograde biliary drainage cannot be performed, PTBD is indicated:
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For treatment of cholangitis. Hydration and antibiotic therapy are successful initial interventions for 80% to 85% of patients with cholangitis. Those with ongoing sepsis despite these therapies require urgent biliary decompression, and those who do respond to initial medical therapies frequently require subsequent biliary drainage.
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To relieve pruritus. Medical therapies including the bile acid–binding resins cholestyramine and colestipol, antihistamines, naloxone, and rifampin are variably effective treatments for pruritus related to cholestasis. Biliary drainage is an effective treatment when results of these medications are suboptimal, even when only one or two segments of the liver can be effectively drained. After biliary drainage for this indication, symptomatic improvement is often observed within 24 hours.
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To relieve symptoms of jaundice. Symptoms such as nausea and anorexia may improve with delivery of bile salts to the intestine.
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To reduce serum bilirubin to allow administration of chemotherapy. Some chemotherapeutic agents require intact mechanisms of bile excretion for safe use, and others require dose modification when the serum bilirubin is elevated. To receive optimal chemotherapy at full dose, some patients may require biliary drainage to lower serum bilirubin.
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Before surgery. Preoperative biliary drainage is highly controversial; many studies have shown it increases complication rates. One meta-analysis suggested neither positive nor negative outcomes in association with preoperative biliary drainage. Others have suggested improved postoperative results after internal drainage.
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In association with other percutaneous biliary procedures such as bile duct biopsy and placement of biliary stents or brachytherapy catheters.
Biliary Stent Placement
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For palliation of symptomatic MBDO in patients unable to undergo endoscopic or surgical treatment.
Contraindications
Percutaneous Transhepatic Cholangiography
There are several relative contraindications to PTC.
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Coagulopathy. Every effort should be made to correct or improve coagulopathy before biliary drainage procedures.
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Allergy to iodinated contrast agents. Patients with history of allergy to iodinated contrast material should be appropriately premedicated because contrast material may be introduced into the vascular system or absorbed during biliary drainage. Typical premedication regimens include administration of both an antihistamine and a corticosteroid.
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Ascites. Large volume ascites may complicate transhepatic biliary access and intervention, and leakage of ascites around biliary catheters may occur. Consider paracentesis in such instances. Left-side biliary access may provide an access window away from ascites.
Percutaneous Transhepatic Biliary Drainage
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All contraindications to PTC.
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Segmental or subsegmental high bile duct obstruction depending on the indication for drainage. Drainage of a biliary tree with multiple isolated blocked ducts is unlikely to provide palliation and may introduce further complications. This should generally be avoided.
Biliary Stent Placement
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All contraindications to PTBD.
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Sepsis. PTBD with minimal manipulation is indicated for patients with sepsis and bile duct obstruction. If appropriate, stent placement can be considered after sepsis has resolved.
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Potential surgical candidates. Because determination of resectability presupposes knowledge of the diagnosis, metallic stents are not placed when the diagnosis is not known. Historically, biliary drainage catheters rather than biliary stents have been placed for preoperative patients. There is a trend in recent literature to suggest that stents can be safely used in preoperative patients with low bile duct obstruction. Because this represents a substantial change in approach, local surgical preferences should be sought and considered.
Equipment
Either moderate sedation or anesthesia services can be used for performance of PTC, PTBD, and biliary stent placement. In either case, patient-monitoring equipment including pulse oximetry and electrocardiographic monitors are required.
Owing to the length of biliary cases and proximity of the operator to the x-ray beam, modern fluoroscopic equipment capable of recording radiation dose must be used. Ceiling-mounted translucent leaded shields or leaded eyeglasses can be used as protective barriers in addition to leaded gowns (i.e., leaded aprons). Example equipment needs are listed below.
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Local anesthetic
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Water-soluble, non-ionic radiographic contrast material
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No. 11 blade or other suitable blade for dermatotomy creation
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21-gauge needle with stylet, capable of accepting a 0.018-inch guidewire
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A coaxial introducer system including an innermost component tapered to accept a 0.018-inch guidewire and an outer 4F or 5F sheath. Examples include the Neff Percutaneous Access Set (Cook Medical, Bloomington, IN) and the GrebSet (Vascular Solutions, Minneapolis, MN).
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4F or 5F catheters (e.g., Berenstein, C2)
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Guidewires, including a torquable 0.035-inch hydrophilic wire and a 0.035-inch Amplatz Super Stiff guidewire (Boston Scientific, Natick, MA)
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6- to 10-mm inflatable balloon catheters
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8F and 10F biliary drainage catheters
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8 and 10 mm self-expanding stents (e.g., Wallstent, Boston Scientific)
Technique
Anatomy and Approach
Understanding the segmental anatomy of the liver is essential for interventional radiologists who perform biliary interventions. The Couinaud classification of liver anatomy ( Fig. 92.1A ) is most useful in this regard. The liver is divided right from left by the plane that includes the middle hepatic vein and gallbladder fossa.
Left Hepatic Lobe
The caudate lobe is segment 1. The lateral segment of the left hepatic lobe comprises segments 2 and 3. Segment 2 is more superior and posterior, and segment 3 is more anterior and inferior. Therefore, left-sided biliary drainages often use segment 3 for access because it is ordinarily the most superficial and inferior portion of the lateral sector under the skin of the epigastrium. The medial segment of the left hepatic lobe, segment 4, is separated from the lateral segment by the umbilical fissure and falciform ligament.
The left hepatic duct is formed by the confluence of tributary bile ducts from segments 1 through 4. The lateral sector ducts (segments 2 and 3) have a typical appearance, joining to create an acute angle to form a single duct that subsequently receives the segment 4 and segment 1 branches, forming the left hepatic duct. The left hepatic duct is characteristically longer than the right. This anatomic fact is functionally important when MBDO is centered at or above the hilus, because progression of disease will usually involve second-order and higher biliary confluences on the right side before the same thing occurs on the left. In such a context, left-sided biliary drainage may be preferred.
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