A 52-year-old woman undergoes ultrasound abdomen for recurrent right upper quadrant pain. Multiple gallstones are identified. Which is the most common site of gallstone impaction leading to acute cholecystitis?

Explanation

## Most Common Site of Gallstone Impaction Leading to Acute Cholecystitis ### Anatomy of Gallstone Impaction **Key Point:** Hartmann's pouch (infundibulum) is the most common site of gallstone impaction leading to acute cholecystitis. Stones lodging here obstruct the cystic duct, triggering the inflammatory cascade of acute cholecystitis. ### Why Hartmann's Pouch? Hartmann's pouch is a mucosal outpouching at the junction of the neck and infundibulum of the gallbladder. It is the most dependent (gravity-dependent) portion of the gallbladder, making it the preferential site where gallstones settle and become impacted. When a stone impacts here, it effectively obstructs the cystic duct outflow, leading to: - Increased intraluminal pressure - Bile stasis and secondary bacterial infection - Mucosal ischemia and inflammation - Acute cholecystitis ### Anatomical Considerations | Site | Frequency | Pathophysiology | | --- | --- | --- | | **Hartmann's Pouch** | Most common | Gravity-dependent; stone impaction obstructs cystic duct → acute cholecystitis | | Neck of GB | Common | Narrowest point; also a site of obstruction | | Body | Rare | Larger diameter; stones usually do not obstruct | | Fundus | Rare | Not near the outflow tract; no obstruction | **High-Yield:** Hartmann's pouch is the infundibulum of the gallbladder — the most dependent part — where stones preferentially collect and impact, obstructing the cystic duct and causing acute cholecystitis. This is the textbook answer per Bailey & Love's Short Practice of Surgery and Schwartz's Principles of Surgery. ### Clinical Pearl Acute cholecystitis occurs when a stone impacted at Hartmann's pouch causes: 1. Obstruction of cystic duct outflow 2. Increased intraluminal pressure 3. Mucosal ischemia and inflammation 4. Secondary bacterial infection (in ~50% of cases) **Mirizzi Syndrome:** When a stone impacted in Hartmann's pouch or the cystic duct extrinsically compresses the common hepatic duct, it causes Mirizzi syndrome — an important surgical complication to recognize. **Tip:** Remember: **Hartmann's pouch = most common impaction site** (gravity-dependent, obstructs cystic duct); **Neck = anatomically continuous with Hartmann's pouch** but Hartmann's pouch is the specific named site cited in surgical textbooks as the most common location. *Reference: Bailey & Love's Short Practice of Surgery, 27th edition; Schwartz's Principles of Surgery, 11th edition.*