What does Kehr's sign indicate?

Kehr's sign is a clinical indication of referred pain associated specifically with splenic injury or ruptured spleen. It is characterized by pain that radiates to the left shoulder, which can occur due to irritation of the diaphragm, particularly from blood accumulating in the peritoneal cavity after a splenic rupture. This phenomenon occurs due to the shared sensory pathways between the diaphragm and the shoulder area, which are both innervated by the phrenic nerve. Thus, when the spleen is injured, the patient may experience pain in an area distant from the injury site, corresponding to the left shoulder. Recognizing this sign is crucial in emergency settings as it can guide healthcare providers in diagnosing splenic injuries promptly.