Following blunt trauma to the abdomen, a 21-year-old female complains of diffuse abdominal pain and pain to the left shoulder. Your assessment reveals that her abdomen is distended and tender to palpation. On the basis of these findings, you should be MOST suspicious of injury to the:

• A. gallbladder.
• B. pancreas.
• C. spleen.
• D. liver.

Answer: (C)

The key idea is Kehr sign—the referred pain to the left shoulder from diaphragmatic irritation due to intra-abdominal bleeding after blunt trauma. Here, the left shoulder pain plus a distended, tender abdomen points to intra-abdominal hemorrhage, and the spleen is the organ most commonly injured in this scenario because it lies in the left upper quadrant and is vulnerable to blunt impact. When the spleen ruptures, blood in the peritoneal cavity irritates the diaphragmatic surface, causing the left shoulder pain.

Gallbladder injury would usually present with right upper quadrant pain; pancreas injury often presents with epigastric pain radiating to the back; liver injury would cause right upper quadrant findings and bleeding signs but not the characteristic left shoulder referred pain.