What is the baseline workup for a patient presenting with abdominal pain?

Baseline Workup for Abdominal Pain

The baseline workup for abdominal pain should include a thorough clinical assessment, appropriate laboratory tests, and imaging studies based on pain location, with ultrasonography recommended for right upper quadrant pain and CT for lower quadrant or diffuse abdominal pain. 1

Initial Clinical Assessment

• Evaluate pain characteristics (location, onset, duration, quality, radiation, aggravating/alleviating factors) to help narrow differential diagnosis 1
• Assess for associated symptoms such as fever, nausea, vomiting, diarrhea, or constipation which may suggest specific etiologies 1
• Document vital signs, as fever may indicate infection or inflammation, and hemodynamic instability may suggest emergent conditions like hemorrhage or sepsis 1
• Perform a complete abdominal examination including inspection, auscultation, percussion, and palpation to identify specific findings such as distension, tenderness, guarding, or rebound tenderness 1

Laboratory Investigations

• Complete blood count to assess for leukocytosis (suggesting infection or inflammation) 1
• C-reactive protein as a marker of inflammation 1
• Liver function tests and hepatobiliary markers, especially for right upper quadrant pain 1
• Serum electrolytes, creatinine, and blood urea nitrogen to assess renal function 1
• Serum lipase for suspected pancreatitis 2
• Urinalysis to evaluate for urinary tract infection or nephrolithiasis 2
• Pregnancy test for all women of reproductive age 1
• Stool analysis and culture, and C. difficile toxin testing when appropriate 1

Imaging Studies

• Selection of imaging modality should be based primarily on the location of pain 1
• Right upper quadrant pain: Ultrasonography is the initial imaging test of choice 1
• Right or left lower quadrant pain: CT scan is recommended 1
• Diffuse or nonlocalized abdominal pain: CT scan with IV contrast is preferred 1
• Conventional radiography (plain abdominal X-rays) has limited diagnostic value in most cases of abdominal pain and should not be routinely used 1, 3
• MRI is an alternative for pregnant patients or those who cannot undergo CT scanning 1
• Point-of-care ultrasound may be useful for specific conditions when expertise exists 1, 2

Special Considerations

• For female patients, consider gynecological causes of abdominal pain (ectopic pregnancy, ovarian torsion, pelvic inflammatory disease) 2
• In elderly patients, atypical presentations are common, and laboratory tests may be normal despite serious infection 1
• In immunocompromised patients, typical signs of abdominal sepsis may be masked 1
• For pregnant patients, ultrasound should be the first-line imaging, with MRI preferred over CT if additional imaging is needed 1

Common Pitfalls to Avoid

• Relying solely on laboratory tests without appropriate imaging, as many conditions require imaging for definitive diagnosis 1, 4
• Failing to consider extra-abdominal causes of abdominal pain (e.g., pneumonia, myocardial infarction) 2
• Missing gynecological emergencies in women of reproductive age 5
• Discharging patients with undiagnosed abdominal pain without clear follow-up plans or return precautions 5
• Overreliance on plain abdominal radiographs, which have low sensitivity and accuracy for many causes of abdominal pain 3

Predictors of Hospital Admission

• Abnormal imaging findings and elevated inflammatory markers (particularly CRP) are significant predictors of the need for hospital admission 4
• Advanced age, elevated white blood cell count, and abnormal vital signs may also indicate more severe pathology requiring admission 4