Introduction
A tube through which something passes is called a duct. A duct that transports bile from the liver and gallbladder to the intestines is called a bile duct. Sometimes, these ducts can get blocked due to scarring or other kinds of blockage. This causes a restriction in the flow of bile to and from the duct. The area where the narrowing occurs is called stricture. Bile duct strictures can cause pain and other gastrointestinal problems. This article deals with bile duct strictures in detail.
What Is a Bile Duct Stricture?
The narrowing of the bile duct, whether intrahepatic or extrahepatic, is called bile duct strictures or biliary strictures. It can be either benign or malignant, depending upon the causative disorders. Most cases are mainly due to some type of malignancy. Constriction of the bile duct reduces bile flow, causing proximal dilatation and bile obstruction and complications.
What Causes a Bile Duct Stricture?
Bile duct strictures can be mainly acquired or sometimes congenital. The acquired strictures are classified into benign and malignant.
Benign Strictures: These strictures contribute to approximately 30 percent of biliary stricture cases, including iatrogenic strictures. During laparoscopic cholecystectomy (a minimally invasive surgical procedure to remove an infected gallbladder), the bile duct or cystic duct can be misidentified, leading to injury in the bile duct. These injuries could be partial or complete, and they can lead to bile duct strictures in an extended stay.
Some other benign causes of strictures are:
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Acute Cholangitis: The inflammation in the gallbladder is called acute cholangitis. It is a chronic syndrome that presents jaundice (yellowing of the skin and white of the eyes), abdominal pain, and fever due to stasis and infection in the bile duct.
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Mirizzi Syndrome:It is a rare condition of the gallbladder. Extrinsic compression in the cystic duct or infundibulum of the gallbladder due to an impacted stone leading to obstruction.
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Chronic Pancreatitis: A long-term inflammation of the pancreas that does not heal can cause bile duct strictures.
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Ischemic Cholangiopathy: When the bile duct gets damaged due to insufficient blood supply, it is called ischemic cholangiopathy. Multiple diffuse intrahepatic strictures lead to a set of disorders.
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Biliary Inflammatory Pseudotumors: Benign, rare, and poorly defined tumors typically diagnosed post-aggressive surgical intervention.
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Orient Cholangiohepatitis: It is characterized by intrahepatic or extrahepatic bile duct strictures and dilation with an intraductal pigmented stone.
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Post-radiation or radiotherapy.
Anastomotic Strictures: These complications occur after orthotopic liver transplantation (a surgical procedure where a healthy one replaces a diseased liver) or a Whipple procedure (surgical removal of the initial parts of the small intestine, gallbladder, and bile duct) performed for pancreatic mass or trauma.
Malignant Strictures: The most common etiology of bile duct stricture is malignancy, such as pancreatic head cancer and cholangiocarcinoma (a rare type of cancer that affects the bile duct).
Some other malignancies involved are:
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Hepatocellular Carcinoma: Liver cancer in people with chronic liver diseases such as cirrhosis due to hepatitis infection. It is the most common type of liver malignancy.
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Lymphoma: It is a cancer of the lymphatic system of the body. The lymphatic system comprises lymph glands, spleen, thymus, and bone marrow.
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Periampullary Cancer: It includes a group of heterogeneous neoplasms (malignant lesions) arising from the distal common bile duct, head of the pancreas, and duodenum.
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Gallbladder Carcinoma: A malignancy infecting the gallbladder that helps store and transport bile from the liver to the intestine.
How Does Bile Duct Stricture Look?
The obstruction of bile flow leads to elevated serum bilirubin and obstructive jaundice. Magnetic resonance cholangitis pancreatic (MRCP) or endoscopic retrograde cholangiopancreatography (ERCP) shows that benign strictures have smooth and symmetric borders with tapered margins. At the same time, malignant strictures have irregular and asymmetric borders with shouldered margins. Benign strictures generally involve small segments, in contrast to malignant strictures, which involve long segments.
What Is the Strasberg-Bismuth Classification of Strictures?
Strasberg-Bismuth classification helps guide the treatment and management of bile duct strictures according to size and location.
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E1: Standard hepatic duct division greater than two centimeters from the bifurcation.
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E2: Standard hepatitis duct division less than two centimeters from the bifurcation.
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E3: Common bile duct dividing at the bifurcation.
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E4: Hilar stricture, which involves junction and loss of communication between the left and right hepatobiliary duct.
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E5: Involvement of aberrant hepatic duct with associated stricture of the common hepatic duct.
What Are the Symptoms of Bile Duct Strictures?
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Bile duct strictures can be asymptomatic with no relevant physical examination.
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Some cases of bile duct strictures may result from obstructive jaundice, which includes yellowing of mucosa and skin, pale stools, and dark urine.
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The obstruction will lead to irregular indigestion, which can lead to symptoms like loss of appetite, nausea, vomiting, fever, and malaise.
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Pain in the upper right side of the abdomen.
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Diarrhea.
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Loss of appetite.
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Pruritus (itchy skin).
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Steatorrhea (the elimination of fat through stool as it does not get digested).
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Severe cases may present with xanthomas (deposition of cholesterol-rich substances in many body parts).
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Weight loss.
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Calcium deficiency.
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Deficiency of fat-soluble vitamins.
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Anemia.
How to Diagnose Bile Duct Stricture?
The first step in investigating the disorder is physical examination. It helps to look for features such as Murphy and Courvoisier signs that diagnose jaundice and the presence of any hard masses in the abdomen pointing towards advanced malignant processes. Murphy's sign is when the patient has pain and stops breathing while the doctor palpates the right subcostal area. In the Courvoisier sign, the patient will have jaundice but no pain on palpating the gallbladder.
Other important investigating options are:
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A partial bile duct obstruction may cause elevated serum alkaline phosphatase (ALP) and gamma-glutamyl transpeptidase (GGT, GGTP) levels, which can rise to three times their normal ranges.
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Prolonged prothrombin time.
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Prolonged international normalized ratio (INR, a blood test that shows how long the blood takes to clot).
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Deranged Liver Function Test: Coagulative profiles help to understand invasive conditions. The presence of specific immunological markers helps to obtain an accurate diagnosis.
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Presence of Assay of CA19-9 and carcinoembryonic antigen in patients with suspected hepatobiliary malignancies.
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CT (computed tomography) scan helps detect the appearance and complications of strictures.
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Ductal dilatation is a significant feature in evaluating bile duct stricture. A trans-abdominal ultrasound shows biliary dilatation and is highly sensitive to biliary obstruction levels.
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MRCP (magnetic resonance cholangiopancreatography) provides high-quality cholangiograms, which help establish the location and extent of biliary strictures. It provides a three-dimensional reconstruction and cross-sectional view of the biliary tree.
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ERCP (Endoscopic retrograde cholangiopancreatography) helps find the cause and acquire tissue samples for cytology and histology.
How to Treat Bile Duct Strictures?
The central management of bile duct strictures is restricted to treating complications from biliary obstruction and causative agents. Endoscopic treatment is the first line of treatment for biliary strictures.
The options for treatment include:
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Stenting: This method manages both benign and malignant bile duct strictures. Before definitive surgery, hyperbilirubinemia or cholangitis is reduced. This step is beneficial for palliation in malignant strictures, which are inoperable.
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Dilatation: This process is used to manage benign stricture. The balloon dilatation technique is used extensively for strictures caused by primary sclerosing cholangitis.
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Resection and Anastomosis: This technique depends on the nature of strictures, whether malignant or benign and on the outcome, which can be palliative or curative.
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Bypass: Choledochoduedenostomy (a surgical procedure that creates anastomosis between the bile duct and the duodenum) can be involved in some instances as hepaticojejunostomy can make it challenging to perform ERCP in the future.
Conclusion.
Bile duct strictures obstruct bile flow due to constrictions in the bile duct. It can be intrahepatic (duct inside the liver) or extrahepatic (duct outside the liver). The symptoms can be biliary complications. The treatment is done through endoscopic approaches such as stenting, bypass, dilatation, and resection. Complications depend on the type of treatment attempted. Pancreatitis is seen in some cases following ERCP. The prognosis of the condition depends on what causes the stricture. Recovery time is also dependent on the type of treatment done. Minimally invasive procedures have a faster recovery and pain when compared to open surgeries.
