A 42-year-old woman from rural Maharashtra presents with a 2-week history of jaundice, pale stools, and dark urine. She reports no fever, abdominal pain, or weight loss. On examination, she is afebrile with mild hepatomegaly and no splenomegaly. Laboratory investigations show: total bilirubin 8.2 mg/dL (direct 6.8 mg/dL), AST 120 IU/L, ALT 145 IU/L, ALP 320 IU/L, and albumin 3.8 g/dL. Abdominal ultrasound reveals dilated intrahepatic and extrahepatic bile ducts with a 1.5 cm stone in the common bile duct. What is the most likely diagnosis?

Explanation

## Clinical Presentation Analysis **Key Point:** The constellation of pale stools, dark urine, and direct hyperbilirubinemia with markedly elevated ALP indicates **biliary obstruction** — not hepatocellular injury. ### Pattern Recognition | Feature | Finding | Interpretation | |---------|---------|----------------| | **Bilirubin pattern** | Direct > indirect | Cholestasis / obstruction | | **Enzyme pattern** | ALP (320) >> ALT (145) | Biliary obstruction, not hepatitis | | **Clinical signs** | Pale stools + dark urine | Complete bile duct obstruction | | **Imaging** | Stone in CBD + dilated ducts | Mechanical obstruction confirmed | | **Fever/pain** | Absent | Uncomplicated obstruction (no cholangitis) | ### Why This Is Obstructive Jaundice 1. **Direct hyperbilirubinemia (6.8/8.2)** — bilirubin is conjugated and cannot be excreted into bile. 2. **ALP disproportionately elevated** — indicates biliary epithelial damage from obstruction. 3. **Ultrasound gold standard** — visualizes the stone and dilated ducts, confirming mechanical obstruction. 4. **No fever** — rules out acute cholangitis; this is uncomplicated choledocholithiasis. **High-Yield:** In obstructive jaundice, ALP rises *before* transaminases and falls *after* them. The ALP:ALT ratio >2 strongly favours biliary obstruction. **Clinical Pearl:** Pale stools (acholia) occur because *no bile reaches the intestine*; dark urine reflects conjugated hyperbilirubinemia being filtered by the kidney. ## Management Pathway ```mermaid flowchart TD A[Jaundice + Pale stools + Dark urine]:::outcome --> B{Direct hyperbilirubinemia?}:::decision B -->|Yes| C{ALP >> ALT?}:::decision C -->|Yes| D[Biliary obstruction]:::outcome D --> E{Imaging shows stone?}:::decision E -->|Yes| F[Choledocholithiasis]:::outcome F --> G{Fever/RUQ pain?}:::decision G -->|No| H[ERCP + sphincterotomy]:::action G -->|Yes| I[Acute cholangitis - urgent ERCP]:::urgent ``` **Citation:** Harrison 21e Ch 309, Robbins 10e Ch 18