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Bile duct strictures are a big problem and one that we encounter on a daily basis. Strictures of the bile duct often lead to clinical jaundice and symptoms of biliary obstruction (pruritus, etc) and warrant investigation.

Bile duct strictures can be intrinsic or extrinsic in nature;

intrinsic strictures arise from primary diseases of the bile ducts themselves, while extrinsic strictures are usually due to compression from another object or organ.

The 2 main tools used to treat biliary strictures are dilation and stenting, both of which are usually per-formed via endoscopy. Biliary strictures can be dilated

using pneumatic or catheter-based dilators during ERCP.

Biliary stricture dilation can also be performed during percutaneous biliary procedures performed by interven-tional radiologists. Stents can be temporary or perma-nent, depending upon the nature of the stricture and the patient’s overall history (ie, a patient with an inflamma-tory stricture due to recent bile duct stone passage will likely be treated with a temporary plastic biliary stent, whereas a patient with metastatic pancreatic cancer and jaundice will usually be treated with a permanent self-expanding metal stent).

Bile duct strictures can arise from several specific causes, including the following:

•Pancreatic cancer: The distal CBD runs through the head of the pancreas. Many pancreatic tumors occur in the head of the gland. As these tumors grow, they can extrinsically compress the distal CBD and lead to clinical jaundice and obstruction.

When detected on imaging studies, simultaneous obstruction of the bile duct and the main pancre-atic duct from a pancrepancre-atic head tumor is known as the double-duct sign (Figure 6-6).

•Cholangiocarcinoma: Primary bile duct cancer is referred to as cholangiocarcinoma.

Cholangiocarcinoma usually results in an intrin-sic biliary stricture. The most common location for bile duct stricture in patients with cholangio-carcinoma is at the common hepatic duct where it bifurcates into the left and right hepatic ducts (although cholangiocarcinoma can develop any-where in the biliary tree). Patients can develop combined left- and right-sided biliary obstruc-tion from a cholangiocarcinoma. Patients with combined left- and right-sided biliary obstruction from cholangiocarcinoma can be difficult to treat;

it can sometimes be difficult to provide adequate biliary drainage to relieve their jaundice.

... Gallbladder and Bile Ducts

•Primary sclerosing cholangitis (PSC): PSC is a chronic inflammatory condition of the bile duct with associated liver dysfunction that often pro-gresses to cirrhosis. Bile duct strictures in PSC are very common. More on this is covered later in this chapter.

•Gallbladder cancer: Primary tumors of the gall-bladder, although rarely encountered, can obstruct the bile duct either by extrinsic compression or direct invasion.

•Biliary surgery: Many biliary strictures are post-surgical in nature. The blood flow to the bile ducts themselves is somewhat tenuous, and the bile ducts tolerate injury poorly. Surgical injury Figure 6-6. Malignant CBD stricture seen via ERCP in a patient with pancreatic cancer. The distal com-mon duct is tightly stenosed (arrow), and the proxi-mal intra- and extrahepatic ducts are all dilated.

to the bile ducts thus often results in the stricture.

Common causes of biliary surgical injury include mechanical injury to the CBD or common hepatic duct during cholecystectomy (where the surgeon accidentally places a clip across the bile duct, accidentally cauterizes the bile duct, etc) or during liver transplantation. Most patients who undergo liver transplantation undergo the creation of what is known as a primary duct-to-duct anastomosis.

This means that the CBD from the donor liver is sewn directly onto the recipient’s native CBD with the 2 ducts forming a single pipe to carry bile from the liver to the duodenum. This anastomotic site is a common location for postsurgical strictures.

Most anastomotic biliary strictures due to liver transplantation are treated with a combination of dilation and stenting and respond well to therapy.

In contrast, injuries of the CBD that occur during cholecystectomy may be much more difficult to treat. Many of these postcholecystectomy injuries require multiple rounds of dilation and stenting, whereas others can only be repaired surgically (with a biliary bypass).

•Bile duct inflammation: Bile duct inflammation can lead to strictures anywhere in the biliary tree.

The bile duct can become inflamed from a variety of causes—choledocholithiasis, PSC or SSC, auto-immune cholangiography, and other causes. These can all lead to inflammatory strictures. Sometimes, it can be difficult to distinguish an inflammatory stricture from a malignant stricture, and tissue sampling may be required to exclude malignancy.

•Acute pancreatitis: Inflammation of the pan-creas can lead to extrinsic compression of the CBD as it courses through the pancreatic head.

Many patients with acute pancreatitis will develop some degree of cholestasis even in the absence

... Gallbladder and Bile Ducts

of choledocholithiasis. As the pancreatitis sub-sides and the swelling around the CBD resolves, the stricture generally disappears spontaneously.

Sometimes, patients with acute pancreatitis will develop pseudocysts that can cause long-lasting compression of the CBD and concomitant jaun-dice. In these cases, patients often receive biliary stents to relieve their jaundice. The pseudocysts may spontaneously resolve or may require endo-scopic and/or surgical drainage.

•Chronic pancreatitis: Patients with chronic pan-creatitis may also develop CBD strictures due to extrinsic compression from inflammation and/or scarring and fibrosis of the pancreatic head. Biliary strictures that arise in the setting of chronic pancreatitis may be extremely difficult to treat. Fibrosis in the pancreatic head due to chronic pancreatitis may be longstanding and may never resolve. Patients with biliary strictures from chronic pancreatitis often require one or more plastic biliary stents (placed side-by-side) in an attempt to provide both biliary drainage and bili-ary stricture dilation simultaneously. Some physi-cians use a covered self-expanding metal stent in an off-label manner in these patients to provide more long-lasting drainage and stricture dilation.

Patients with calcific chronic pancreatitis who develop a biliary stricture are more likely to have a poor outcome. These patients may never resolve their stricture regardless of prolonged biliary stent-ing. Some patients with intractable biliary stric-tures from chronic pancreatitis have to undergo surgery (usually in the form of a biliary bypass) to definitively treat their biliary obstruction.

•Metastatic cancer: Patients with tumors that are metastatic to the liver (or, rarely, the pancre-atic head) can develop a biliary stricture due to

extrinsic compression from metastases. Patients in this situation are generally treated with biliary stents with good outcome.

•Adenopathy: Some patients will develop a biliary stricture due to extrinsic compression from a peri-ductal lymph node. This can be seen in patients with advanced cancer and/or primary hematologic malignancies, such as lymphoma. These patients are typically treated with biliary stents. The stents can often be removed if the underlying adenopa-thy can be resolved via chemotherapy, radiation therapy, etc.