Final answer:
The symptoms suggest injury to the spleen due to blunt trauma to the abdomen, which can cause referred pain to the left shoulder. The spleen is located in the upper-left quadrant and is susceptible to rupture in such cases.
Step-by-step explanation:
The symptoms of left upper quadrant abdominal pain with referred pain to the left shoulder, distended and tender abdomen, and Kehr's sign (pain in the left shoulder, chest, and neck regions) suggest injury to the spleen. In cases of blunt trauma to the abdomen, the spleen, which is located in the upper-left quadrant, is susceptible to rupture. When the spleen ruptures, blood spills into the diaphragm, leading to referred pain in the shoulder and neck.