What are the possible causes of left upper quadrant abdominal pain?

Causes of Left Upper Quadrant Abdominal Pain

Primary Differential Diagnosis

Left upper quadrant (LUQ) abdominal pain arises from splenic pathology, pancreatic disorders, gastric conditions, renal pathology, colonic disorders, and functional disorders, with chronic pancreatitis being the most common pancreatic cause. 1

Organ-Specific Etiologies

Splenic Causes:

• Splenic infarction, abscess, hematoma, or rupture—particularly in patients with trauma history or coagulopathy 1
• Splenic injury presents with LUQ pain accompanied by referred left shoulder pain, signs of hypovolemic shock, or diffuse abdominal discomfort 2

Pancreatic Causes:

• Chronic pancreatitis is the most common pancreatic source of chronic LUQ pain 1
• Acute pancreatitis confirmed by serum amylase >4× normal or lipase >2× upper limit 2

Gastric and Esophageal Causes:

• Functional dyspepsia is the most common cause of postprandial LUQ pain when structural abnormalities are excluded, characterized by pain or burning in the upper abdomen, early satiety, or postprandial heaviness 2
• Peptic ulcer disease and gastritis 1

Renal Causes:

• Nephrolithiasis can cause chronic LUQ pain 1
• Pyelonephritis 2

Colonic Causes:

• Splenic flexure diverticulitis or colitis extending to the LUQ 2
• Diverticulitis, though more common in the left lower quadrant, can also cause LUQ pain 1

Atypical Presentations:

• Left-sided appendicitis due to intestinal malrotation—CT can detect unexpected findings including malrotation with atypical appendicitis 2, 3

Vascular Causes:

• Chronic mesenteric ischemia should be considered if the patient has postprandial pain with weight loss and atherosclerotic risk factors 2

Life-Threatening Conditions to Exclude:

• Perforated viscus (rebound tenderness with abdominal distension occurs in 82.5% of patients with peritonitis) 2
• Splenic rupture 1
• Mesenteric ischemia 1

Diagnostic Approach Algorithm

Step 1: Initial Laboratory Workup

• Complete blood count to assess for leukocytosis indicating infection or inflammation 4
• Pancreatic enzymes (amylase and lipase) to rule out pancreatitis 4
• Liver function tests including ALT, AST, alkaline phosphatase, GGT, and bilirubin 4
• Renal function tests (BUN, creatinine) 4
• Pregnancy test for all women of reproductive age before imaging to avoid unnecessary radiation exposure and missed ectopic pregnancy 1, 4
• Urinalysis to evaluate for renal stones or infection 4

Step 2: Risk Stratification

• Measure serum C-reactive protein (CRP) to aid in risk-stratifying inflammatory conditions and guide urgency of further imaging 2
• Elevated white blood cell count with left shift suggests infection or inflammation, which may indicate splenic abscess, pancreatitis, or diverticulitis 4

Step 3: Imaging Selection

• CT abdomen and pelvis with IV contrast is the preferred initial imaging modality, providing comprehensive assessment with excellent diagnostic accuracy 1, 2
• CT has moderate sensitivity (69%) and excellent specificity (100%) for acute LUQ pathology 5
• CT alters diagnosis in nearly half of cases and changes management decisions in 25-49% of patients 2
• Plain radiography has very limited diagnostic value for LUQ pain and is not recommended 2
• Ultrasound has limited utility in this location due to overlying bowel gas and rib shadowing, though it may identify splenic or renal pathology 2
• MRI may be useful as a second-line imaging study if CT is non-diagnostic and symptoms persist, with sensitivity of 86-94% for certain conditions 1

Critical Clinical Pearls

Red Flags Requiring Immediate Imaging:

• Fever and leukocytosis indicate inflammatory or infectious processes requiring urgent imaging 2
• Rebound tenderness with abdominal distension suggests perforation or abscess, mandating immediate emergency surgical evaluation 2
• Recent colonoscopy within 48 hours with abdominal pain, distension, and rebound tenderness strongly suggests perforation 2

Common Diagnostic Pitfalls:

• Normal laboratory values do not exclude serious pathology—imaging studies may still be necessary based on clinical presentation 1, 4
• Failing to obtain a pregnancy test in women of reproductive age before imaging can lead to unnecessary radiation exposure and missed ectopic pregnancy 1, 4
• Relying solely on laboratory tests without appropriate imaging when clinical suspicion warrants further investigation 1, 4
• Functional disorders should be considered only after organic pathology is confidently excluded 1, 6
• Once functional pain diagnosis is established, avoid repetitive testing 1, 6