Etiology and Pathology
Intrahepatic bile duct stones, also known as hepatolithiasis, represent a common but challenging biliary disease. The etiology is complex and primarily associated with factors such as biliary infections, parasitic infestations (e.g., Ascaris worms, Clonorchis sinensis), bile stasis, anatomical variations in bile ducts, and malnutrition. The majority of the stones are brown pigment stones containing bacteria, typically distributed in hepatic segments or liver lobes, with a predilection for the left lateral lobe and the right posterior lobe. This distribution is related to poor bile drainage due to the anatomical relationship of their bile duct confluence with the common hepatic duct. Intrahepatic bile duct stones can easily migrate into the common bile duct, becoming secondary extrahepatic bile duct stones.
The pathological changes associated with this condition include the following:
Obstruction of Intrahepatic Bile Ducts
Obstruction may arise from stone impaction or inflammatory strictures caused by recurrent cholangitis. Proximal to the obstruction, bile ducts may dilate and become filled with stones. Prolonged obstruction can result in fibrosis or atrophy of the liver segments or lobes upstream of the obstruction.
Intrahepatic Cholangitis
Stones obstructing bile flow increase the risk of biliary infections, leading to recurrent cholangitis and worsening ductal strictures. Acute infections may result in complications such as suppurative cholangitis, liver abscesses, sepsis, or biliary bleeding.
Intrahepatic Cholangiocarcinoma
Chronic exposure of intrahepatic bile ducts to stones, inflammation, and carcinogenic substances in bile predisposes them to malignant transformation.
Clinical Manifestations
Some patients are asymptomatic, while others experience vague upper abdominal and thoracic-back discomfort or distension. The majority present with acute cholangitis, characterized by chills, high fever, and abdominal pain. Jaundice is uncommon unless the disease involves the common bile duct or bilateral hepatic bile duct stones. Severe cases may progress to acute obstructive suppurative cholangitis, septicemia, or septic shock.
Recurrent cholangitis may cause multiple liver abscesses. Larger abscesses may rupture through the diaphragm into the lungs, forming biliary-bronchial fistulas, which can lead to coughing up bile-stained sputum or biliary sand. Prolonged obstruction can result in liver cirrhosis, manifesting as jaundice, ascites, portal hypertension, upper gastrointestinal bleeding, or liver failure.
In cases of persistent abdominal pain, progressive weight loss, uncontrolled infection, palpable abdominal masses, or mucinous discharge from abdominal wall fistulas, the possibility of intrahepatic cholangiocarcinoma should be considered. Physical examination may reveal tenderness or percussion pain over the liver, and in a few cases, asymmetrical or enlarged hepatic lobes may be palpable. Additional complications may present with corresponding physical signs.
Laboratory Tests
In acute cholangitis, white blood cell counts are elevated with a left shift in neutrophils, and liver enzyme abnormalities are common. Significant elevation of tumor markers such as CA19-9 or CEA should raise suspicion for malignancy.
Diagnosis
Imaging studies are essential for diagnosing intrahepatic bile duct stones in patients with recurrent abdominal pain accompanied by chills and high fever.
Ultrasonography is capable of detecting intrahepatic bile duct stones and their distribution. The extent of bile duct dilation can help determine the site of strictures, but distinctions must be made between intrahepatic calcifications and stones. Calcifications are generally not associated with bile duct dilation.
Imaging Techniques like PTC (Percutaneous Transhepatic Cholangiography), ERCP (Endoscopic Retrograde Cholangiopancreatography), and MRCP (Magnetic Resonance Cholangiopancreatography) allow direct visualization of the biliary tree. These studies can identify negative images of stones, bile duct strictures, and dilated proximal ducts. Other findings may include incomplete visualization of the biliary tree, absence of opacification in certain ducts, and asymmetric images of the left and right bile ducts.
CT or MRI is particularly valuable for diagnosing liver cirrhosis or malignancy associated with intrahepatic bile duct stones.
Treatment
Asymptomatic and small intrahepatic bile duct stones may not require treatment, with ongoing observation and regular follow-up being sufficient. Symptomatic cases or those with imaging findings suggesting segmental liver atrophy or bile duct stricture warrant surgical intervention. The principles of surgery include thorough removal of stones, resolution of bile duct strictures and obstructions, elimination of the affected areas and sources of infection, restoration or establishment of unobstructed bile drainage, and prevention of recurrence. Surgical methods include the following:
Bile Duct Exploration for Stone Removal
This is the most fundamental approach, aiming to open the narrowed bile duct segment. A longitudinal incision is made along the common bile duct, which may extend upward to the secondary bile ducts. Stones are removed under direct vision or via intraoperative cholangioscopy until complete clearance is achieved.
Biliary-Enteric Bypass
This procedure does not replace the treatment of ductal strictures or stone-affected areas. When the sphincter of Oddi retains its function, biliary-enteric bypass should be avoided. The most common approach involves Roux-en-Y hepaticojejunostomy. Indications include:
- Persistent incomplete clearance of intrahepatic bile duct stones despite adequate dilation and remodeling of biliary strictures.
- Loss of function of the sphincter of Oddi with associated intrahepatic duct dilation and stones but no strictures.
- The need to create a subcutaneous blind jejunal loop for repeat postoperative interventions in cases prone to recurrent stones or other biliary diseases.
To prevent anastomotic strictures after the procedure, placement of a stent tube for drainage and support may be required. The stent can be externalized through the intestinal lumen or the liver surface, or a U-shaped tube may be used with both ends emerging from the intestinal lumen and liver surface. To reduce the risk of restenosis after stent removal, the stent should remain in place for approximately one year.
Hepatectomy
Recurrent infections caused by intrahepatic bile duct stones often result in localized liver atrophy, fibrosis, and functional loss. Resection of the affected liver segments or lobes, including the stones, infected areas, and strictures, removes the source of recurrent stones and prevents malignant transformation of the diseased liver tissue. This is considered an active treatment method for intrahepatic bile duct stones. Indications include:
- Regional intrahepatic stones accompanied by fibrosis, atrophy, abscesses, or bile fistulas.
- Stones in segments or lobes of the liver with significant bile duct dilation, where complete stone removal is difficult.
- High bile duct strictures with proximal duct stones, where surgical access is challenging.
- Localized stones associated with biliary bleeding.
- Stones with concurrent cholangiocarcinoma.
Intraoperative Adjunctive Measures
Intraoperative imaging methods such as biliary cholangiography and ultrasound are useful for determining the location and number of stones. Cholangioscopy can assist with intraoperative diagnosis, lithotripsy, and stone removal.
Management of Residual Stones
Residual stones after surgery for intrahepatic bile duct stones are relatively common, with an incidence of 20%–40%. Therefore, postoperative treatment plays an essential role in addressing residual stones. Treatment options include choledochoscopic stone removal through the drainage tube tract (sinus tract), or lithotripsy methods such as laser, ultrasound, or plasma lithotripsy.