Differential Diagnosis for Dilated Common Bile Duct with Normal Hepatic Function Panel

Single Most Likely Diagnosis

• Choledocholithiasis: This condition, where a gallstone is lodged in the common bile duct, is a common cause of ductal dilation. The presence of a stone can cause obstruction, leading to dilation, even if liver function tests (LFTs) are normal, as the obstruction may not significantly affect liver function until later stages.

Other Likely Diagnoses

• Chronic Pancreatitis: Inflammation of the pancreas can cause scarring and strictures in the common bile duct, leading to dilation. Patients may have normal LFTs if the pancreatitis is not currently active or if the bile duct obstruction is partial.
• Ampullary Stenosis: Narrowing at the ampulla of Vater, where the bile and pancreatic ducts empty into the small intestine, can cause bile duct dilation. This condition might not affect liver function tests significantly, especially in early stages.
• Bile Duct Stricture: A narrowing of the bile duct, which can be due to various causes including previous surgery, trauma, or inflammation, can lead to dilation of the bile duct upstream of the stricture.

Do Not Miss Diagnoses

• Cholangiocarcinoma: A cancer of the bile duct, which can cause dilation due to obstruction. Although less common, missing this diagnosis can have severe consequences, making it crucial to consider, even with normal LFTs.
• Pancreatic Cancer: A tumor in the head of the pancreas can obstruct the common bile duct, leading to dilation. Early detection is critical, and this condition should not be overlooked, even if LFTs are normal.

Rare Diagnoses

• Congenital Bile Duct Cysts (Choledochal Cysts): These are rare congenital anomalies of the bile duct that can cause dilation. They might not affect liver function significantly until later in life or if they become complicated.
• Primary Sclerosing Cholangitis (PSC): A chronic liver disease that leads to scarring, inflammation, and destruction of the bile ducts inside and outside the liver. While it often affects LFTs, early stages or less severe forms might present with normal liver function tests.
• Parasitic Infections (e.g., Ascaris lumbricoides): In rare cases, parasitic infections can cause bile duct obstruction and subsequent dilation. This is more common in endemic areas and might not significantly affect LFTs until the infection is advanced.