What is the recommended approach to evaluating and managing abdominal pain in an adult patient?

Approach to Abdominal Pain in Adults

For acute abdominal pain in adults, use pain location to guide your imaging strategy: obtain ultrasonography for right upper quadrant pain, and CT abdomen/pelvis with IV contrast for nonlocalized pain, lower quadrant pain, or when the diagnosis remains unclear after initial assessment.

Initial Clinical Assessment

Begin by assessing hemodynamic stability, then focus your history and physical examination on these key discriminators:

Critical History Elements

• Pain location and migration pattern (most useful predictor of etiology)
• Onset and duration (acute <7 days vs chronic)
• Associated symptoms: fever, vomiting, constipation/distension (suggests obstruction), changes in bowel habits
• Red flag features: age >50, weight loss, blood in stool, severe unremitting pain, immunocompromised state

Physical Examination Priorities

• Localized vs diffuse tenderness
• Peritoneal signs (guarding, rigidity, rebound)
• Abdominal distension (strongly suggests obstruction when present with constipation)
• Pulsatile mass (consider AAA)

Essential Laboratory Testing

Order selectively based on clinical suspicion:

• Pregnancy test (mandatory in all women of reproductive age before imaging) 1
• Complete blood count, C-reactive protein
• Hepatobiliary markers (if RUQ pain)
• Lipase (if epigastric pain)
• Urinalysis (if flank/suprapubic pain)
• Electrolytes, creatinine, glucose

Location-Based Imaging Algorithm

Right Upper Quadrant Pain

Ultrasonography is the initial imaging study of choice 1. This approach:

• Detects cholecystitis with high sensitivity
• Avoids radiation exposure
• Can be performed rapidly at bedside

If ultrasonography is equivocal, consider cholescintigraphy or CT 1.

Right or Left Lower Quadrant Pain

CT abdomen/pelvis with IV contrast is the initial imaging study of choice 1. This provides:

• High sensitivity for appendicitis, diverticulitis
• Broad diagnostic capability for alternative diagnoses
• Rapid acquisition without need for oral contrast 2

Nonlocalized/Diffuse Abdominal Pain

CT abdomen/pelvis with IV contrast is usually appropriate 2. This approach:

• Screens for the broad differential (abscess, perforation, obstruction, ischemia, malignancy)
• Changes leading diagnosis in ~50% of cases and alters management in 25% 2
• Should be performed without oral contrast to avoid delays (oral contrast adds minimal diagnostic value) 2

Important caveat: If IV contrast is contraindicated, CT without contrast is acceptable but has reduced sensitivity for inflammatory conditions and vascular pathology 2.

Special Populations

Women of Reproductive Age

• Always obtain beta-hCG before imaging 1
• Consider gynecologic causes: ectopic pregnancy, ovarian torsion, PID
• If pregnant and imaging needed: ultrasonography first, then MRI if inconclusive (avoid CT) 2

Elderly Patients

• Have lower threshold for imaging—laboratory tests may be falsely reassuring despite serious pathology 2
• Higher risk of life-threatening conditions (mesenteric ischemia, AAA, perforated viscus)
• May present with atypical symptoms

Immunocompromised/Neutropenic Patients

• CT abdomen/pelvis with IV contrast is usually appropriate 2
• High mortality risk if diagnosis delayed 2
• Consider atypical infections, opportunistic organisms, typhlitis
• Clinical signs may be masked despite serious infection 2

Postoperative Patients

• CT abdomen/pelvis with IV contrast to evaluate for anastomotic leak, abscess, or hemorrhage 2

Role of Conventional Radiography

Conventional radiography has limited diagnostic value 1. It should be reserved for:

• Suspected free air (upright chest X-ray more sensitive than abdominal films)
• Suspected bowel obstruction (moderate sensitivity ~49%) 2
• Suspected foreign body ingestion (90% sensitivity) 2

Do not obtain plain films for nonspecific abdominal pain—they delay definitive imaging and rarely change management 2.

Point-of-Care Ultrasonography

When available and operator is skilled, bedside ultrasound can rapidly identify:

• Cholecystitis/cholelithiasis
• Hydronephrosis/urolithiasis
• Appendicitis (in experienced hands)
• Free fluid/hemoperitoneum
• Abdominal aortic aneurysm

This can expedite diagnosis before formal imaging 3.

Common Pitfalls to Avoid

1. Delaying imaging for oral contrast administration—most institutions no longer use oral contrast routinely as it delays care without improving diagnostic accuracy 2

2. Obtaining plain films first—this delays definitive CT imaging and adds radiation without diagnostic benefit in most cases 1, 2

3. Forgetting pregnancy testing—always check beta-hCG before imaging women of reproductive age 1

4. Underestimating severity in elderly—they may have normal labs despite serious pathology; maintain low threshold for CT 2

5. Ordering CT without IV contrast when not contraindicated—this significantly reduces diagnostic sensitivity 2

When Imaging May Not Be Required

Consider clinical diagnosis without imaging for:

• Typical uncomplicated diverticulitis in known diverticular disease 1
• Clear-cut viral gastroenteritis
• Urolithiasis with classic presentation and hematuria (though CT often still obtained)

However, maintain low threshold for imaging when diagnosis uncertain, as CT changes management in 25-50% of cases 2.