What is the referred pain in the shoulder caused by blood in the peritoneal cavity?

• A. Rovsing's sign
• B. Murphy's sign
• C. Kehr's sign
• D. Cullen's sign

Answer: (C)

Referred shoulder pain from blood in the peritoneal cavity is Kehr’s sign. Free blood irritates the diaphragmatic peritoneum, and the phrenic nerve (primarily the C3–5 fibers that feed into the C4 dermatome) sends pain to the shoulder, typically the left side. This finding points to intra-abdominal bleeding, such as from splenic rupture or other hemoperitoneum, and signals a need for urgent evaluation. The other signs are different phenomena: Rovsing’s sign is rebound pain in the right lower quadrant from appendicitis, Murphy’s sign is inspiratory arrest with gallbladder palpation in cholecystitis, and Cullen’s sign is periumbilical bruising from pancreatitis or intra-abdominal bleeding, not shoulder pain. Kehr’s sign is the shoulder manifestation of diaphragmatic irritation due to intra-abdominal bleeding.