What is the appropriate initial assessment and management for a patient presenting with left upper quadrant pain?

Initial Assessment and Management of Left Upper Quadrant Pain

Order CT abdomen and pelvis with IV contrast immediately for any patient presenting with left upper quadrant (LUQ) pain—this is the gold-standard imaging modality with near-perfect diagnostic accuracy and should not be delayed for plain radiographs or ultrasound. 1

Immediate Clinical Evaluation

Focus your history and physical examination on these specific features:

• Fever and leukocytosis indicate inflammatory or infectious processes (abscess, pancreatitis, splenic pathology) requiring urgent imaging 1
• Postprandial timing suggests gastric, pancreatic, or mesenteric ischemia—if pain occurs 15-30 minutes after eating with weight loss and atherosclerotic risk factors, obtain CT angiography to evaluate for chronic mesenteric ischemia 1
• Rebound tenderness with abdominal distension occurs in 82.5% of peritonitis cases and mandates immediate surgical consultation 1
• Referred left shoulder pain (Kehr sign) suggests splenic injury or rupture, particularly in trauma patients 1
• Recent colonoscopy within 48 hours combined with LUQ pain and distension strongly indicates perforation 1

Laboratory Assessment

Order these tests before imaging:

• Complete blood count with differential—leukocytosis with left shift (≥75% neutrophils) suggests bacterial infection 2
• C-reactive protein—CRP >170 mg/L predicts severe inflammatory disease with 87.5% sensitivity and 91.1% specificity 2
• Serum lipase and amylase—lipase >2× upper limit or amylase >4× normal confirms acute pancreatitis 1
• Lactate level—elevated lactate signals sepsis and metabolic derangement requiring aggressive resuscitation 2
• β-hCG in all women of reproductive age before CT to exclude ectopic pregnancy 2

Imaging Strategy

CT abdomen and pelvis with IV contrast is rated 8/9 (usually appropriate) by the American College of Radiology and provides comprehensive evaluation of all LUQ pathology with 69% sensitivity and 100% specificity. 1, 3

Why CT is mandatory:

• Detects unexpected findings including malrotation with atypical appendicitis that would be missed clinically 1
• Alters diagnosis in 49% of cases with nonlocalized abdominal pain 1
• Identifies complications requiring immediate intervention (perforation, abscess, vascular occlusion) 1
• Evaluates splenic trauma with near-perfect accuracy in hemodynamically stable patients 1

Avoid these imaging pitfalls:

• Do not order plain radiographs—they have very limited diagnostic value for LUQ pain and delay definitive diagnosis 1
• Do not rely on ultrasound as the primary modality—overlying bowel gas and rib shadowing severely limit visualization in the LUQ, though it may identify splenic or renal pathology 1
• Do not skip IV contrast unless contraindicated—unenhanced CT misses abscesses, vascular pathology, and bowel wall abnormalities 1

Differential Diagnosis Framework

Structure your clinical reasoning around these organ systems:

Splenic Pathology

• Splenic infarction, abscess, or rupture—look for left shoulder pain, signs of hypovolemia, or history of trauma 1, 4
• In trauma patients, free fluid isolated to the LUQ occurs in 6% of positive FAST exams, most commonly in the left paracolic gutter (84% of LUQ fluid) 4

Pancreatic Disease

• Acute pancreatitis—confirmed by lipase >2× upper limit; mortality <10% in uncomplicated cases, <30% in severe disease 1
• Post-procedure pancreatitis—consider if recent ERCP or embolization; presents with nausea, vomiting, and fever 1

Gastric and Colonic Causes

• Splenic flexure diverticulitis or colitis—CT provides high diagnostic accuracy for detecting bowel wall thickening and pericolic inflammation 1
• Perforated viscus—free intraperitoneal air on CT has 92% positive predictive value and requires immediate surgical consultation 1

Renal Pathology

• Pyelonephritis or nephrolithiasis—obtain urinalysis to screen; CT will definitively diagnose 1

Vascular Emergencies

• Mesenteric ischemia—suspect in patients >60 years with postprandial pain, weight loss, and atherosclerotic disease; obtain CT angiography 1

Immediate Management Based on Findings

If CT shows perforation or peritonitis:

• NPO status, IV fluid resuscitation, nasogastric decompression 1
• Broad-spectrum antibiotics immediately after blood cultures 1
• Emergency surgical consultation—do not delay for additional testing 1

If CT confirms pancreatitis:

• Supportive care with IV fluids, pain control, and antiemetics 1
• Monitor for complications—necrosis, pseudocyst, or systemic inflammatory response 1

If CT identifies splenic trauma in hemodynamically stable patients:

• Non-operative management is preferred regardless of injury grade, with splenic preservation rates of 95-100% 1
• Limit follow-up imaging to reduce radiation exposure 1
• Transfuse only after three 20 mL/kg crystalloid boluses in adolescents 1

If CT is negative but symptoms persist:

• Consider functional dyspepsia—test for H. pylori and treat if positive; offer PPI or H2-receptor antagonist 1
• Refer to gastroenterology if alarm features present (age >50, weight loss, anemia, family history of GI malignancy) 1

Critical Pitfalls to Avoid

• Do not assume benign etiology without imaging—clinical assessment alone has a 34-68% misdiagnosis rate 1
• Do not perform colonoscopy during acute presentation—colonic distention increases perforation risk; postpone 6-8 weeks if indicated 5
• Do not dismiss normal inflammatory markers—39% of complicated diverticulitis cases have CRP <175 mg/L 2
• Do not delay CT for ultrasound in adults—ultrasound is operator-dependent and limited by body habitus 1