What is the appropriate management for a patient presenting with abdominal pain?

Management of Abdominal Pain

For patients presenting with acute abdominal pain, obtain a focused history and physical examination, followed by CT scan with IV contrast for nonlocalized or diffuse pain, while reserving ultrasound for right upper quadrant pain and obtaining mandatory pregnancy testing in all women of reproductive age before imaging. 1, 2

Initial Clinical Assessment

The evaluation must rapidly identify whether urgent surgical intervention is required while avoiding unnecessary testing 3, 4:

• Document pain characteristics systematically: exact location, onset timing (sudden vs. gradual), duration, quality (sharp, cramping, burning), radiation patterns, and factors that worsen or improve symptoms 2
• Assess vital signs immediately: fever suggests infection or inflammation; hemodynamic instability (hypotension, tachycardia) indicates potential hemorrhage, sepsis, or bowel ischemia requiring emergent intervention 2
• Identify associated symptoms: fever, nausea, vomiting, diarrhea, constipation, or changes in bowel habits help narrow the differential diagnosis 2
• Perform complete abdominal examination: inspect for distension or surgical scars, auscultate for bowel sounds, percuss for tympany or dullness, and palpate systematically for tenderness, guarding, rebound tenderness, or masses 2

Critical pitfall: In elderly patients, typical signs may be absent and laboratory values may appear normal despite serious infection, requiring a lower threshold for imaging 1, 2

Mandatory Laboratory Testing

Order these tests for all patients with acute abdominal pain 2, 5:

• Complete blood count (CBC): leukocytosis indicates infection or inflammation (appendicitis, diverticulitis, cholecystitis) 2, 5
• Comprehensive metabolic panel: includes liver function tests (ALT, AST, alkaline phosphatase, bilirubin), electrolytes, creatinine, and BUN to assess organ function and identify hepatobiliary pathology 2, 5
• Serum lipase: more specific than amylase for pancreatitis diagnosis 5
• Urinalysis: evaluates for urinary tract infection or nephrolithiasis 2, 5
• Pregnancy test (β-hCG): mandatory in all women of reproductive age before any imaging to avoid missing ectopic pregnancy 2, 5

Additional testing based on clinical suspicion 5:

• Blood cultures if sepsis suspected (fever with hemodynamic instability)
• Lactate and D-dimer if mesenteric ischemia considered (though these lack specificity)
• C-reactive protein as inflammatory marker 2
• Stool studies and C. difficile toxin if diarrhea present 2

Imaging Strategy Based on Pain Location

The American College of Radiology provides clear guidance on imaging selection 1, 2, 5:

Right Upper Quadrant Pain

• Ultrasound is the initial imaging test of choice for suspected cholecystitis, cholelithiasis, or hepatobiliary pathology 2, 5

Right or Left Lower Quadrant Pain

• CT scan is recommended for suspected appendicitis or diverticulitis 2, 5
• CT demonstrates superior sensitivity compared to ultrasound (94% vs. 76% for appendicitis, 81% vs. 61% for diverticulitis) 1

Diffuse or Nonlocalized Abdominal Pain

• CT scan with IV contrast is the preferred imaging modality 1, 2, 5
• CT plays an essential role in determining management, with studies showing the leading diagnosis changed in 51% of patients and admission decisions changed in 25% of patients after CT results 1
• Common pathologies detected include small bowel obstruction, pancreatitis, nephrolithiasis, GI perforation, bowel ischemia, and intra-abdominal abscesses 1

Important caveat: Plain abdominal radiographs have limited diagnostic value and should not be routinely ordered 2, 5

Special Populations

Pregnant patients 2:

• Ultrasound should be first-line imaging
• MRI is preferred over CT if additional imaging needed to avoid radiation exposure

Immunocompromised/neutropenic patients 1:

• CT with IV contrast is the initial modality due to high risk of neutropenic enterocolitis (28%) and small bowel obstruction (12%)
• Typical signs of abdominal sepsis may be masked 2
• Lower threshold for imaging given atypical presentations

Postoperative patients with fever 1:

• CT with IV contrast to evaluate for postoperative abscess or anastomotic leak
• MRI demonstrates 100% accuracy for detecting abdominal abscesses and can distinguish infected from noninfected fluid 1

Management of Specific Conditions

Intra-abdominal Abscess

• Abscesses >3 cm or with evidence of fistula require percutaneous drainage 1
• Abscesses <3 cm without fistula and no steroid therapy may respond to antibiotics alone, though with high recurrence rates 1
• Antibiotic coverage: fluoroquinolones or third-generation cephalosporin PLUS metronidazole to cover Gram-negative bacteria and anaerobes 1
• Clinical improvement should occur within 3-5 days; if not, repeat imaging and consider drain repositioning or surgery 1

Inflammatory Bowel Disease Patients

The World Journal of Emergency Surgery provides specific guidance 1:

• Multidisciplinary management involving gastroenterologist and acute care surgeon is optimal 1
• Supportive care: adequate IV fluids, low molecular weight heparin for thromboprophylaxis, correct electrolyte abnormalities and anemia 1
• Antibiotics are NOT routinely administered, only if superinfection or intra-abdominal abscess present 1
• For severe active ulcerative colitis: IV corticosteroids if hemodynamically stable, assess response by day 3 1
• For non-responders: consider infliximab with thiopurine or ciclosporin in multidisciplinary approach 1

Critical warning: Preoperative immunomodulators with anti-TNF-α agents and steroids increase risk of intra-abdominal sepsis in emergency surgery 1

When Imaging is Negative or Equivocal

• Do not repeat imaging routinely if functional disorder suspected after organic pathology confidently excluded 6
• Consider MRI as alternative to CT, particularly with rapid acquisition protocols showing 99% accuracy for various pathologies including small bowel obstruction, diverticulitis, and abscesses 1
• Nuclear medicine studies (FDG-PET/CT) may be useful for fever of unknown origin when cross-sectional imaging is inconclusive 1

Key Pitfalls to Avoid

• Never proceed with CT imaging in women of reproductive age without pregnancy testing 2, 5
• Do not rely solely on laboratory tests without appropriate imaging, as many surgical conditions require imaging for definitive diagnosis 2
• Avoid plain radiographs as routine initial imaging—they have poor sensitivity and CT provides superior diagnostic yield 1, 2, 5
• Do not dismiss elderly patients with normal labs—serious infections can present atypically with normal laboratory values in this population 1, 2
• Recognize that immunocompromised patients may lack typical inflammatory signs, requiring lower threshold for advanced imaging 1, 2