What is the approach to evaluating and managing abdominal pain in a patient with a variable demographic and medical history, including potential diagnoses such as irritable bowel syndrome (IBS) or cardiovascular disease?

Systematic Approach to Abdominal Pain

Begin by determining whether the pain is acute (requiring urgent evaluation for surgical emergencies) or chronic (present >3-6 months), as this fundamentally changes your diagnostic and management pathway. 1, 2

Acute Abdominal Pain Evaluation

Immediate Risk Stratification

In patients with acute abdominal pain and cardiovascular disease history, suspect acute intestinal ischemia—this is a surgical emergency. 1

• Classic presentation: severe abdominal pain out of proportion to physical findings in patients with atrial fibrillation, recent MI, or history of arterial interventions 1
• Laboratory findings typically show leukocytosis and lactic acidosis; approximately 50% have elevated amylase 1
• Do NOT order duplex ultrasound for suspected acute intestinal ischemia—abdominal distention precludes successful scanning and delays definitive treatment 1
• CT scanning may show atherosclerotic disease, arterial thrombosis, or late findings like pneumatosis intestinalis, but treatment should not be delayed for imaging 1

Red Flag Assessment

Screen immediately for alarm features that mandate urgent investigation or referral: 1, 3, 2

• Age >45-50 years
• Documented weight loss
• Rectal bleeding
• Nocturnal symptoms that wake the patient
• Anemia
• Fever
• Family history of colon cancer or inflammatory bowel disease

Initial Workup for Acute Pain

Obtain: 3, 2

• Complete blood count
• C-reactive protein or ESR
• Liver function tests
• Amylase (if upper abdominal pain)
• Lactate (if vascular disease suspected)

If red flags are present or the patient is hemodynamically unstable, immediate surgical consultation and imaging (CT scan preferred for lower quadrant pain; ultrasound for right upper quadrant) are indicated. 4

Chronic Abdominal Pain Evaluation

Establishing Chronicity

Symptoms must be present for at least 6 months before considering functional diagnoses like IBS, with active symptoms for the past 3 months. 3

Targeted History Elements

Focus on specific symptom patterns rather than vague descriptions: 1, 5

• Pain relationship to defecation: Does pain improve after bowel movement? (suggests IBS)
• Stool pattern changes: Are stools looser or more frequent with pain onset? (suggests IBS)
• Meal relationship: Does eating trigger or worsen pain? (suggests functional disorder or biliary disease)
• Nocturnal symptoms: Pain that wakes patient from sleep suggests organic disease, not functional disorder 1, 3

Supportive Features for Functional Diagnosis

IBS is more likely if: 1

• Female patient
• Age <45 years
• Symptom duration >2 years
• Frequent prior visits for non-gastrointestinal complaints
• Associated symptoms: bloating, mucus in stool, incomplete evacuation, lethargy, fibromyalgia, urinary frequency

Essential Laboratory Exclusions

Before diagnosing functional pain, obtain: 3

• Complete blood count
• C-reactive protein or ESR
• Celiac serology (anti-endomysial or tissue transglutaminase antibodies)
• Fecal calprotectin (to exclude inflammatory bowel disease)
• Stool examination for ova and parasites if travel history or persistent diarrhea 3

Thyroid function testing and stool microscopy each reveal abnormalities in only 1-2% of cases, so reserve these for specific clinical suspicion. 1

Imaging Decisions

• Sigmoidoscopy with biopsy is indicated for colonic symptoms to detect microscopic colitis, even if mucosa appears normal 1
• Avoid repeated imaging once functional diagnosis is established 5

Management Framework

When Organic Disease is Identified

For inflammatory bowel disease with acute pain: 1

• Multidisciplinary approach with gastroenterology and surgery
• IV fluids, electrolyte correction, thromboprophylaxis
• Antibiotics only if superinfection or abscess present—not routine 1
• Abscesses >3 cm: percutaneous drainage plus antibiotics as first-line 1
• Abscesses <3 cm: IV antibiotics with close monitoring 1

For severe ulcerative colitis: IV corticosteroids if hemodynamically stable, assess response by day 3 1

When Functional Pain is Diagnosed

First-line pharmacologic treatment: tricyclic antidepressants starting at low dose, titrating slowly. 5

• Explain mechanism as "gut-brain neuromodulator" to improve acceptance 5
• Second-line: SSRIs if tricyclics not tolerated 5
• For more severe symptoms: SNRIs 5
• Antispasmodics for meal-related pain exacerbation 5

Non-pharmacologic interventions: 5

• Cognitive behavioral therapy if symptoms persist despite 12 months of drug treatment
• Gut-directed hypnotherapy for visceral hypersensitivity

Critical Management Pitfalls

Avoid these common errors: 5

• Never use opioids chronically—risk of narcotic bowel syndrome, dependence, serious infection, and mortality
• Do not repeat costly investigations once functional diagnosis is established
• Do not dismiss pain as "functional" without appropriate initial evaluation
• Set early expectations that pain is real but multifactorial
• Monitor for hypervigilance and central sensitization in chronic pain

Reassessment Strategy

If initial workup is negative and no alarm features present: 3, 2

• Reassess in 3-6 months
• If symptoms persist without new alarm features and repeat investigations remain normal, functional diagnosis is appropriate
• Refer for psychological support rather than ordering repetitive testing

Special Population Considerations

Elderly patients: May present with atypical or absent clinical signs despite serious pathology—maintain higher index of suspicion 1, 4

Women of reproductive age: Always consider genitourinary causes including ectopic pregnancy, ovarian torsion, and pelvic inflammatory disease 4

Post-surgical patients or those with IBD: Consider adhesions, strictures, or fistulae as pain sources 1