## Distinguishing Acute from Chronic Cholecystitis ### Key Imaging Features **Key Point:** Sonographic Murphy's sign is the single best discriminator between acute and chronic cholecystitis. It represents pain elicited by direct palpation over the gallbladder during ultrasound, indicating acute inflammation. ### Comparison Table | Feature | Acute Cholecystitis | Chronic Cholecystitis | | --- | --- | --- | | **Sonographic Murphy's sign** | **Positive** ✓ | Negative | | **Gallbladder wall thickness** | >3 mm (acute edema) | >3 mm (fibrosis) | | **Gallstones** | Usually present | Usually present | | **Pericholecystic fluid** | Often present | Absent | | **Clinical presentation** | Acute RUQ pain, fever | Recurrent biliary colic | **High-Yield:** Sonographic Murphy's sign has 95% sensitivity and 86% specificity for acute cholecystitis when combined with clinical symptoms. It is the **only feature that reliably distinguishes acute from chronic** disease. ### Why Other Features Fail to Discriminate - **Gallstones alone:** Present in both acute and chronic disease; 10–15% of population has asymptomatic cholelithiasis. - **Wall thickening:** Occurs in both conditions (acute edema vs. chronic fibrosis); cannot distinguish based on thickness alone. - **Dilated CBD and fatty infiltration:** Non-specific findings unrelated to acute vs. chronic distinction. **Clinical Pearl:** A patient with chronic cholecystitis and gallstones who develops acute inflammation will show a **positive Murphy's sign**—this is the clinical trigger for acute superimposition. **Mnemonic:** **MURPH** = **M**ost **U**seful **R**adio **P**rocedure for **H**yperacute cholecystitis detection. 
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