Diagnostic Approach for Stomach Pain
For patients presenting with stomach pain, ultrasonography is the initial imaging study of choice for right upper quadrant pain, while CT with contrast media is recommended for right lower quadrant, left lower quadrant, or generalized abdominal pain. 1
Initial Laboratory Evaluation
- Complete blood count (CBC) to assess for leukocytosis, which may indicate infection or inflammation 2
- Comprehensive metabolic panel including liver function tests to evaluate for hepatobiliary pathology 2
- Urinalysis to evaluate for urinary tract infection or nephrolithiasis 2
- Serum lipase for suspected pancreatitis, as it is more specific than amylase 2
- Beta-human chorionic gonadotropin testing in all women of reproductive age before performing diagnostic imaging 1, 2
Imaging Based on Pain Location
Right Upper Quadrant Pain
- Ultrasonography is the first-line imaging modality 1, 3
- Consider cholescintigraphy or CT if ultrasonography is equivocal for suspected cholecystitis 1
Right or Left Lower Quadrant Pain
- CT of abdomen and pelvis with contrast media is the initial imaging study of choice 1, 4
- For suspected appendicitis or diverticulitis, CT with contrast is recommended 1
Diffuse/Nonlocalized Abdominal Pain
- CT of abdomen and pelvis with contrast media is typically the imaging modality of choice 1, 4
- Consider CT angiography with contrast media if mesenteric ischemia is suspected 1
Special Considerations
- For patients with fever and abdominal pain, obtain blood cultures and perform a chest radiograph 1
- For patients who have recently undergone thoracic, abdominal, or pelvic surgery, perform CT as part of the workup if etiology is not readily identified 1
- Plain radiographs have limited diagnostic value in the assessment of abdominal pain and should not be routinely used 1, 3
- For suspected mesenteric ischemia, elevated lactate, leukocytosis, and D-dimer may assist in diagnosis, though none are definitive 1
Laboratory Tests Based on Suspected Diagnosis
- For suspected cholecystitis: CBC, liver function tests 1, 2
- For suspected appendicitis: CBC with differential, C-reactive protein 2, 4
- For suspected pancreatitis: Lipase, amylase 1, 2
- For suspected mesenteric ischemia: Lactate, D-dimer 1, 2
Common Pitfalls to Avoid
- Failing to obtain pregnancy testing in women of reproductive age before proceeding with imaging studies 1, 2
- Relying solely on laboratory tests for diagnosis, as findings early in disease may be of limited value 2, 4
- Using conventional radiography as the initial imaging study, as it has limited diagnostic value 1, 3
- Over-reliance on a single laboratory parameter, as no single test is sufficiently accurate to identify ischemic or necrotic bowel 1
Algorithm for Evaluation
- Obtain relevant laboratory tests based on clinical presentation
- Select appropriate imaging based on pain location:
- Right upper quadrant → Ultrasonography
- Right/left lower quadrant → CT with contrast
- Diffuse/nonlocalized → CT with contrast
- Consider additional specialized testing based on initial findings and clinical suspicion
By following this evidence-based approach, clinicians can efficiently diagnose the cause of stomach pain while minimizing unnecessary testing and radiation exposure.