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

Management of Abdominal Pain

For acute nonlocalized abdominal pain, CT abdomen and pelvis with IV contrast is the preferred initial imaging modality, as it changes the leading diagnosis in 51% of patients and alters admission decisions in 25% of cases. 1

Initial Clinical Evaluation

The diagnostic approach must rapidly identify whether urgent surgical intervention is required versus conservative management. 2, 3

Key history elements to document:

• Pain characteristics: exact location, onset timing, duration, quality, radiation pattern, and factors that worsen or improve symptoms 4
• Associated symptoms: fever (suggests infection/inflammation), nausea, vomiting, diarrhea, constipation 4
• Vital signs assessment: fever indicates possible infection; hemodynamic instability suggests hemorrhage or sepsis 4

Physical examination priorities:

• Complete abdominal exam including inspection, auscultation, percussion, and palpation 4
• Identify specific findings: distension, focal tenderness, guarding, rebound tenderness, or peritoneal signs 4

Laboratory Workup

Essential initial tests:

• Complete blood count to assess for leukocytosis indicating infection or inflammation 4
• C-reactive protein as an inflammation marker 4
• Pregnancy test for all women of reproductive age (mandatory) 4
• Liver function tests and hepatobiliary markers for right upper quadrant pain 4
• Serum electrolytes, creatinine, and BUN for renal function 4
• Stool studies and C. difficile toxin testing when diarrhea is present 4

Imaging Strategy

Location-based imaging algorithm:

For nonlocalized/diffuse abdominal pain:

• CT abdomen and pelvis with IV contrast is the first-line study 1, 4
• This modality detects appendicitis, cholecystitis, small bowel obstruction, pancreatitis, renal colic, perforated ulcer, cancer, and diverticulitis 1
• CT changes management in 51% of patients and admission status in 25% 1

For right upper quadrant pain:

• Ultrasound is the initial imaging test of choice 4

For right or left lower quadrant pain:

• CT scan is recommended 4

Alternative imaging modalities:

• MRI with rapid acquisition protocols achieves 99% overall accuracy for acute abdominal pathology and can detect small bowel obstruction, diverticulitis, pelvic inflammatory disease, pyelonephritis, and abscesses 1
• MRI is preferred for pregnant patients or those who cannot undergo CT 4
• Ultrasound has lower sensitivity (75%) and specificity (91%) compared to CT (88% and 93% respectively) for detecting intra-abdominal abscesses 1

Avoid this common pitfall:

• Plain abdominal radiographs have limited diagnostic value and should not be routinely used 4

Special Population Considerations

Elderly patients:

• Atypical presentations are common 4
• Laboratory tests may be normal despite serious infection 1, 4
• Imaging is especially critical as clinical signs may be masked 1

Immunocompromised/neutropenic patients:

• Typical signs of abdominal sepsis may be masked 4
• CT with IV contrast is the initial modality of choice 1
• Most frequent causes are neutropenic enterocolitis (28%) and small bowel obstruction (12%) 1
• Diagnosis may be delayed with high mortality risk 1

Postoperative patients with fever:

• Fever raises concern for postoperative abscess or anastomotic leak 1
• CT with IV contrast is essential for detecting fluid collections, hemorrhage, or vascular injuries 1
• CT can guide percutaneous drainage when abscess is identified 1

Pregnant patients:

• Ultrasound should be first-line imaging 4
• MRI is preferred over CT if additional imaging is needed 4

When Imaging is Negative or Pain Persists

If CT is negative but clinical suspicion remains high:

• Consider FDG-PET/CT for fever of unknown origin when cross-sectional imaging is inconclusive 1
• MRI may detect pathology missed on CT, particularly for mucosal lesions 1

For chronic pain after inflammation resolves:

• Recognize that pain may transition from acute inflammatory to chronic centralized pain 1
• Risk factors for chronicity include: history of chronic pain, early-life trauma, catastrophizing, anxiety, depression 1
• Address central pain mechanisms with neuromodulation (low-dose tricyclic antidepressants or SNRIs) and brain-gut behavioral therapies 1
• Refer to psychology for cognitive behavioral therapy or hypnotherapy when baseline therapy fails 1

Critical Management Principle

Do not rely solely on laboratory tests without appropriate imaging, as many life-threatening conditions require imaging for definitive diagnosis. 4 The broad differential diagnosis—ranging from benign to life-threatening pathology—necessitates systematic imaging to avoid missed diagnoses and ensure appropriate treatment. 1, 2