What is the next step in the workup for a patient with unspecified left upper quadrant pain?

Workup for Unspecified Left Upper Quadrant Pain

CT abdomen and pelvis with IV contrast is the first-line imaging modality for evaluating unspecified left upper quadrant pain, as it provides the highest diagnostic accuracy and can detect the wide range of pathologies that present in this location. 1

Initial Laboratory Evaluation

Order the following tests for all patients presenting with left upper quadrant pain:

• Complete blood count (CBC) to assess for leukocytosis suggesting infection, inflammation, or splenic pathology 2
• Comprehensive metabolic panel including liver enzymes (ALT, AST, alkaline phosphatase, bilirubin) to evaluate hepatobiliary disease 2
• Pancreatic enzymes (amylase and lipase) as pancreatitis is a common cause of LUQ pain 2, 1
• Pregnancy test for all women of reproductive age to exclude ectopic pregnancy before imaging 2, 1
• Urinalysis to evaluate for renal stones or infection 2

Imaging Strategy

CT abdomen/pelvis with IV contrast should be obtained when:

• The diagnosis remains unclear after initial evaluation 1, 3
• Clinical suspicion warrants further investigation despite normal laboratory values 1
• The patient has alarm features or concerning clinical presentation 3

CT with IV contrast changes the leading diagnosis in up to 51% of patients and alters management decisions in 25% of cases with abdominal pain 1, 3. The contrast enhancement is critical for detecting bowel wall pathology, vascular abnormalities, and intraabdominal fluid collections 1.

Alternative Imaging Considerations

Ultrasound is preferred as initial imaging in specific populations:

• Pregnant patients to avoid radiation exposure 1
• Young patients where radiation is a concern 1
• Premenopausal women when gynecologic pathology is suspected 1

Unenhanced CT is appropriate when IV contrast is contraindicated, though it has limitations in detecting vascular pathology and abscesses 1. In elderly patients (≥75 years), unenhanced CT maintains similar accuracy to contrast-enhanced CT 1.

Common Pathologies to Consider

The differential diagnosis for LUQ pain includes:

• Splenic pathology: infarction, abscess, hematoma, or torsion (the "upside down spleen" sign on coronal CT reconstruction) 3, 4
• Pancreatic disorders: acute or chronic pancreatitis (most common pancreatic cause) 2, 3
• Gastric conditions: gastritis, peptic ulcer disease 3
• Renal pathology: nephrolithiasis, pyelonephritis 2, 3
• Colonic disorders: diverticulitis extending to LUQ 3
• Atypical appendicitis: rare but important, particularly with intestinal malrotation 5, 6

Critical Pitfalls to Avoid

• Never rely solely on laboratory tests without appropriate imaging when clinical suspicion warrants further investigation; normal laboratory values do not exclude serious pathology 2, 1
• Do not use plain radiography as primary imaging as it has limited sensitivity for most LUQ pathology, though it may detect pneumoperitoneum or bowel obstruction 1, 3
• Always obtain pregnancy test before imaging in women of reproductive age to avoid unnecessary radiation and missed ectopic pregnancy 2, 3
• Consider atypical appendicitis even with LUQ pain, especially if intestinal malrotation is present 5, 6
• Avoid delaying imaging in elderly patients who may present with atypical symptoms despite normal laboratory values 1

Additional Testing Based on Clinical Suspicion

Order second-line tests when specific pathology is suspected:

• Lactate level if mesenteric ischemia or severe infection is suspected 2
• Coagulation studies (PT/INR, PTT) if splenic rupture, hematoma, or bleeding disorder is suspected 2