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 to localize the pain, then proceed directly to CT scan with IV contrast for nonlocalized or diffuse pain, or ultrasound for right upper quadrant pain, as imaging is essential for diagnosis and significantly changes management in approximately 50% of cases. 1, 2

Initial Clinical Assessment

Key History Elements to Obtain:

• Pain characteristics: exact location, onset (sudden vs gradual), duration, quality (sharp, cramping, burning), radiation pattern, and factors that worsen or improve symptoms 2
• Associated symptoms that narrow the differential: fever (suggests infection/inflammation), nausea/vomiting, diarrhea, constipation, or changes in bowel habits 2
• Vital signs with particular attention to fever (infection/inflammation) and hemodynamic instability (hemorrhage or sepsis) 2

Physical Examination Findings:

• Complete abdominal examination including inspection for distension, auscultation for bowel sounds, percussion, and palpation for specific tenderness, guarding, or rebound tenderness 2
• In elderly patients, recognize that typical signs may be absent despite serious infection, and laboratory tests may be falsely reassuring 1, 2
• In immunocompromised patients, typical signs of abdominal sepsis are often masked 1, 2

Imaging Strategy (Primary Diagnostic Tool)

CT with IV contrast is the preferred initial imaging for nonlocalized or diffuse abdominal pain because it changes the leading diagnosis in 49-51% of cases, alters admission decisions in 24-25% of cases, and modifies surgical plans in 25% of patients 1. CT demonstrates superior sensitivity compared to ultrasound for most acute abdominal pathologies 1.

Location-Based Imaging Algorithm:

• Right upper quadrant pain: Ultrasound is first-line 2, 3
• Right or left lower quadrant pain: CT scan is recommended 2, 3
• Diffuse or nonlocalized pain: CT with IV contrast is preferred 1, 2
• Pregnant patients: Ultrasound first-line; MRI if additional imaging needed (avoid CT) 2
• Patients who cannot receive CT: MRI with rapid acquisition protocols can achieve 99% accuracy for detecting diverse pathologies including small bowel obstruction, diverticulitis, pyelonephritis, and abscesses 1

Avoid plain abdominal radiographs as they have limited diagnostic value and low sensitivity for most acute abdominal pathologies 1, 2.

Laboratory Investigations

Essential baseline tests:

• Complete blood count to assess for leukocytosis (infection/inflammation) 2
• C-reactive protein as inflammation marker 2
• Liver function tests and hepatobiliary markers, particularly for right upper quadrant pain 2
• Serum electrolytes, creatinine, and blood urea nitrogen for renal function 2
• Pregnancy test mandatory for all women of reproductive age 2
• Stool studies and C. difficile toxin testing when diarrhea present 2

Specific Clinical Scenarios

When Fever is Present with Abdominal Pain:

• Fever significantly raises concern for intra-abdominal abscess, requiring urgent cross-sectional imaging 1
• CT with IV contrast can detect abscesses with 88% sensitivity and 93% specificity (superior to ultrasound at 75% sensitivity) 1
• Common etiologies include appendicitis (one-third of cases), cholecystitis, diverticulitis, pancreatitis, and intra-abdominal abscesses 1
• CT can guide percutaneous drainage when abscess is identified 1

Postoperative Patients:

• Fever with abdominal pain primarily concerning for postoperative abscess or anastomotic leak 1
• CT with IV contrast is the imaging modality of choice 1
• MRI can detect abdominal abscesses with 100% accuracy when standard T2-weighted and post-contrast T1-weighted sequences are used 1

Neutropenic Patients:

• Most common causes are neutropenic enterocolitis (28%) and small bowel obstruction (12%) 1
• CT with IV contrast is the initial imaging modality of choice due to high spatial resolution 1
• Diagnosis may be delayed as typical signs of sepsis are masked 1

Inflammatory Bowel Disease Patients:

• Multidisciplinary approach involving gastroenterologist and acute care surgeon is optimal 1
• Provide adequate IV fluids, low molecular weight heparin for thromboprophylaxis, and correct electrolyte abnormalities and anemia 1
• Antibiotics should NOT be routinely administered, only if superinfection or intra-abdominal abscess is present 1
• When antibiotics are indicated, use fluoroquinolones or third-generation cephalosporin plus metronidazole to cover gram-negative bacteria and anaerobes 1
• For severe active ulcerative colitis in hemodynamically stable patients, IV corticosteroids are initial treatment 1

Critical Pitfalls to Avoid

• Do not rely solely on laboratory tests without imaging, as many conditions require imaging for definitive diagnosis and laboratory values may be normal despite serious pathology, especially in elderly patients 1, 2
• Do not order plain radiographs routinely as they rarely change management and delay definitive imaging 1, 2
• Do not skip pregnancy testing in women of reproductive age before proceeding with imaging decisions 2
• Do not assume typical presentations in elderly or immunocompromised patients, as they frequently present atypically 1, 2
• In inflammatory bowel disease, do not give antibiotics empirically without evidence of infection or abscess 1