Diagnostic Approach and Management of Left Upper Abdominal Pain with Shoulder Pain

Immediate Life-Threatening Considerations

The American College of Radiology recommends checking vital signs immediately for hypotension, tachycardia, or altered mental status, as these indicate possible intra-abdominal hemorrhage from splenic rupture or other vascular catastrophe requiring emergent surgery 1.
Referred left shoulder pain (Kehr's sign) suggests diaphragmatic irritation from blood or fluid in the left upper quadrant, most commonly from splenic pathology 2.
Assess for peritonitis by examining for diffuse tenderness, guarding, rebound tenderness, or absent bowel sounds, which indicate possible perforation requiring emergent surgery 1.
Pain out of proportion to exam findings is the hallmark of mesenteric ischemia, which carries 30-90% mortality and requires immediate vascular imaging 1.

CT abdomen/pelvis with IV contrast is the diagnostic test of choice, with 98% diagnostic accuracy for evaluating upper abdominal pathology and detecting complications 1, 2.
The American College of Radiology recommends ultrasound as first-line imaging for right upper quadrant pain to evaluate for cholecystitis, but for left upper quadrant pain, CT with IV contrast provides superior evaluation of splenic, pancreatic, gastric, and vascular pathology 2.
CT with IV contrast detects splenic hematoma, laceration, infarction, abscess, pancreatic inflammation, gastric perforation, and alternative diagnoses including renal pathology 1, 2.

Splenic rupture or subcapsular hematoma presents with left upper quadrant pain, left shoulder pain, and potential hemodynamic instability requiring immediate surgical consultation 2.
Splenic infarction causes acute left upper quadrant pain and may occur in patients with atrial fibrillation, endocarditis, or hypercoagulable states 2.
Gastric perforation presents with sudden severe pain, peritonitis, and free air on CT requiring emergent surgery 1, 2.
Pancreatitis causes epigastric pain radiating to the back, elevated lipase, and CT findings of pancreatic inflammation 2.
Left renal colic from urolithiasis can cause left upper quadrant pain radiating to the flank and groin, diagnosed by CT showing hydronephrosis or stones 1.
Pyelonephritis presents with fever, costovertebral angle tenderness, and pyuria 2.
Acute coronary syndrome can present with epigastric or left upper quadrant pain and requires ECG and troponin evaluation 2.

Immediate surgical consultation is required for signs of peritonitis, free air on CT, hemodynamic instability, or clinical deterioration despite medical management 1, 2.
Activate massive transfusion protocol if splenic rupture with hemorrhagic shock is suspected 2.
Obtain CT abdomen/pelvis with IV contrast to identify the source and guide treatment 1, 2.
Initiate supportive care with IV fluids, antiemetics, and analgesics (avoid NSAIDs if bleeding suspected) 2, 3.

Do not rely on clinical assessment alone, as misdiagnosis rates range from 34-68% without imaging 1, 4.
Do not delay imaging in patients with left shoulder pain accompanying left upper quadrant pain, as this combination suggests serious intra-abdominal pathology 2.
Do not administer NSAIDs until bleeding sources are excluded, as they can worsen hemorrhage 2.
Do not discharge patients with unexplained left upper quadrant pain and shoulder pain without definitive imaging, as delayed splenic rupture can occur hours to days after initial injury 2.

If intra-abdominal infection is identified, initiate broad-spectrum antibiotics promptly, especially in septic patients 2.
For community-acquired infection: Ertapenem 1g q24h or Eravacycline 1mg/kg q12h 4.
For septic shock: Meropenem 1g q6h by extended infusion, Doripenem 500mg q8h by extended infusion, or Imipenem/cilastatin 500mg q6h by extended infusion 4.
Duration: 4 days post-source control for uncomplicated infections in immunocompetent patients, extending to 7 days for immunocompromised or critically ill patients based on clinical response 2, 4.