Jaundice

Anatomy, embryology, pathophysiology

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Jaundice refers to the clinical sign of hyperbilirubinemia (>2.5 mg/dL), often manifesting with yellowing of the cutaneous surfaces, sclerae conjunctiva, and oral mucosa.
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Largely subdivided into nonobstructive (prehepatic and hepatic etiologies) and obstructive (posthepatic etiologies).
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Prehepatic causes:
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  Hemolytic anemia.
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  Hypersplenism.
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  Artificial heart valves.
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  Sepsis and low perfusional states.
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Hepatic causes:
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  Hepatocellular injury (e.g., viral hepatitis, drug-induced hepatitis, cirrhosis).
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  Infiltrative disease (malignancy, steatohepatitis).
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  Inherited conditions (e.g., Gilbert syndrome, Crigler-Najjar syndrome, etc.).
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Posthepatic or obstructive jaundice:
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  Benign causes:
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    Choledocholithiasis.
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    Biliary stricturing (infectious/inflammatory/iatrogenic causes, such as primary sclerosing cholangitis, posttrauma, postsurgical).
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    Extrabiliary compression (e.g., Mirrizzi syndrome, fluid collections, pancreatic pseudocysts).
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  Malignant causes:
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    Pancreatic, gallbladder, hepatocellular, and biliary malignancies.
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    Portal lymphadenopathy (metastatic, infectious, or primary lymphoproliferative disorder).

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Ultrasound (US) is the preferred initial diagnostic modality for the assessment of the hepatobiliary system, particularly in the setting of acute right upper quadrant pain.
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US has a sensitivity of 48% to 100% and specificity of 64% to 100% for acute cholecystitis.
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The sensitivity of US in detecting gallstones is excellent (sensitivity >95%).
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The sensitivity of US in detection of biliary dilatation is 55% to 91%, demonstrating improved sensitivity with higher serum bilirubin and longer duration of jaundice.
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  Common hepatic duct: Measured inner-inner wall, should measure less than 7 mm in patients under 60 years of age and less than 10 mm in patients older than 60 years of age.
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  Common bile duct (CBD): In patients in their 40s, the normal value is about 4 mm, with the normal mean diameter increasing 1 mm per decade. The upper normal limit is 8.5 mm (or 10 mm postcholecystectomy).
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US has similar sensitivity to computed tomography (CT) for detecting choledocholithiasis (75% in the dilated ducts, 50% in the nondilated ducts).
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US can be used for hepatocellular disease screening (such as hepatocellular carcinoma [HCC] screening, performed every 3–6 months).

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Routine CT abdomen pelvis can evaluate the hepatobiliary system with a large field of view, with highly precise imaging during 3+ phases of hepatic enhancement.
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Optimal acquisition timing, in conjunction with thinner collimation, allows for improved lesion detection, lesion characterization and careful staging of various malignant etiologies (e.g., pancreatic malignancy, hepatic metastases, etc.).
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Routine contrast enhanced CT is moderately sensitive for the detection of choledocholithiasis (sensitivity 65%–88%).
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Routine contrast enhanced CT offers rapid and accurate staging.
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CT cholangiography:
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  Biliary tree imaging for evaluation of postoperative bile leaks, strictures, choledocholithiasis, obstructing lesions and delineation of the biliary anatomy.
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  Uses oral or intravenous (IV) cholangiographic contrast agents (e.g., IV meglumine iotroxate/Biliscopin).
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  Contraindicated in severe hepatic, thyroid or renal dysfunctions, bilirubin less than 30 mmol/L, or iodinated-contrast allergies; radiation exposure.

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Noninvasive way to visualize intra-/extrahepatic biliary system and pancreatic duct.
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Performed on a 1.5 T or higher magnetic resonance imaging (MRI) scanner, using phased-array body coils.
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Requires 4 hours of fasting before the examination to reduce gastrointestinal secretions, minimize gallbladder motility/motion artifact and optimize gallbladder filling.
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Other modified techniques include:
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  Secretin-stimulated magnetic resonance cholangiopancreatography (MRCP): Allows temporary dilation of the pancreatic duct, thus improving exocrine pancreatic reserve assessment and enhancing diagnostic capabilities of MRCP in pancreatic disorders.
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  Functional MRCP: Improves anatomic delineation and enhancing of abnormal pancreaticobiliary variations and evaluation of pancreatic exocrine function.