Kehr sign
Summary
Kehr sign is acute left shoulder pain (referred to the tip of the shoulder) caused by irritation of the diaphragm, classically from splenic rupture with intraperitoneal blood. It is worsened by lying supine or in Trendelenburg position and reflects phrenic nerve (C3-C5) referred pain.
Detail
DEFINITION: Kehr sign is pain in the tip of the left shoulder (supraclavicular/acromial region) due to irritation of the left hemidiaphragm by blood or other irritants in the peritoneal cavity. It is most classically associated with splenic rupture/injury (e.g., blunt trauma to the left upper quadrant or lower left ribs, infectious mononucleosis with splenomegaly).
PATHOPHYSIOLOGY: The diaphragm's central portion is innervated by the phrenic nerve (C3, C4, C5: "C3, 4, 5 keeps the diaphragm alive"). Irritation of the diaphragmatic peritoneum sends visceral/somatic afferent signals via the phrenic nerve. Because these fibers enter the cord at the same levels as the supraclavicular nerves (C3-C4) that supply the shoulder skin, the brain misinterprets the pain as coming from the shoulder (referred pain). The peripheral diaphragm is supplied by intercostal nerves (T5-T11), so peripheral irritation causes local pain instead.
CLINICAL FEATURES AND SIGNIFICANCE: - Left shoulder pain, often with left upper quadrant tenderness, signs of hypovolemia (tachycardia, hypotension), and peritoneal signs. - Pain is accentuated by lying supine or in the Trendelenburg position (blood pools under the diaphragm) and may be relieved by sitting upright. - Suggests hemoperitoneum, so it is a red flag in trauma patients.
CAUSES OF KEHR SIGN: - Splenic rupture (classic; left shoulder). - Ruptured ectopic pregnancy (hemoperitoneum). - Ruptured hepatic lesions or liver laceration (can cause right shoulder pain). - Perforated viscus with free air or fluid under the diaphragm. - Subphrenic abscess, and post-laparoscopy retained CO2 (shoulder pain after laparoscopic surgery).
Left vs. right: a left-sided sign suggests a splenic cause. Right shoulder pain suggests hepatobiliary or right diaphragmatic irritation (e.g., cholecystitis, liver injury).
RELATED SIGNS (often confused on boards): - Balance sign: fixed dullness to percussion in the left flank (clotted blood) and resonance in the right flank (fluid) in splenic rupture. - Cullen sign (periumbilical ecchymosis) and Grey Turner sign (flank ecchymosis): retroperitoneal hemorrhage, e.g., hemorrhagic pancreatitis. - Murphy sign: inspiratory arrest on RUQ palpation (cholecystitis).
MANAGEMENT (Step 2 CK pearls): - Trauma with hypotension and a positive FAST exam: emergent exploratory laparotomy. - Hemodynamically stable: CT abdomen/pelvis with contrast, then observation or angioembolization. - Splenectomy requires vaccination against encapsulated organisms (S. pneumoniae, H. influenzae type b, N. meningitidis); look for Howell-Jolly bodies on smear. - In a woman of childbearing age with shoulder pain, hypotension, and a positive pregnancy test, consider a ruptured ectopic pregnancy.
HIGH-YIELD TAKEAWAY: Left shoulder pain + trauma or mononucleosis + hypovolemia = think splenic rupture (Kehr sign). Mechanism = phrenic nerve (C3-C5) referred pain.
Sources
- First Aid for the USMLE Step 1
- Current Medical Diagnosis & Treatment (CMDT)
- Schwartz's Principles of Surgery
- Bailey & Love's Short Practice of Surgery
- UpToDate: Management of splenic injury in adults
- Gray's Anatomy for Students (phrenic nerve and referred pain)
Reviewed by Medusa editorial — medical student review. Information here is for study reference only and is not medical advice. Spotted an error? Let us know.