What is the approach to managing abdominal pain?

Approach to Abdominal Pain

The evaluation of abdominal pain requires a systematic, location-based approach that prioritizes identifying red flag features requiring urgent intervention, followed by targeted imaging (ultrasound for right upper quadrant, CT for lower quadrants), and when chronic functional disorders are suspected, early initiation of neuromodulators rather than repetitive testing. 1

Initial Assessment: Red Flags and Organ Failure

The first priority is identifying patients requiring immediate surgical consultation or resuscitation:

• Search for signs of organ failure: fever, tachycardia, tachipnea, hypotension, oliguria, altered mental status, and lactic acidosis indicate potential sepsis or surgical emergency 1
• Assess pain characteristics systematically: location, radiation, intensity, aggravating/relieving factors, and temporal pattern guide differential diagnosis 1
• Identify alarm features: These include positive psoas sign, fever, pain migration to right lower quadrant (suggesting appendicitis), or vomiting occurring after pain onset (vomiting before pain makes appendicitis less likely) 1

Location-Based Imaging Strategy

Right Upper Quadrant Pain:

• Ultrasound is first-line imaging for evaluating biliary pathology 1

Right Lower Quadrant Pain:

• CT scan is the recommended imaging modality for suspected appendicitis and other right lower quadrant pathology 1

Left Lower Quadrant Pain:

• CT scan is the recommended imaging modality for evaluating diverticulitis and other left-sided pathology 1

Risk Stratification

Classify patients based on risk factors to determine urgency of intervention 1:

• High-risk features: Advanced age, immunosuppression, malignancy, significant comorbidities 1
• These patients warrant expedited evaluation and lower threshold for imaging and specialist consultation 1

Acute Management When Sepsis/Infection Identified

If intra-abdominal sepsis is confirmed:

• Initiate IV fluid resuscitation immediately 1
• Start broad-spectrum antimicrobials covering gram-negative aerobes/facultative organisms, gram-positive streptococci, and obligate anaerobes 1
• Provide thromboprophylaxis with low molecular weight heparin 1
• Correct electrolyte abnormalities and anemia 1
• Administer early analgesia—this does not compromise diagnostic accuracy 1

Chronic Abdominal Pain: When Organic Disease is Excluded

After confidently excluding organic pathology through appropriate targeted testing:

First-Line Treatments

• Recommend regular exercise for all patients with functional abdominal pain 2
• Initiate soluble fiber (ispaghula) at 3-4 g/day, titrating gradually to avoid bloating; avoid insoluble fiber (wheat bran) which exacerbates symptoms 2
• Consider antispasmodics for global symptoms and pain, though dry mouth, visual disturbance, and dizziness are common 2
• Loperamide may help diarrhea but titrate carefully to avoid constipation, bloating, and nausea 2

Second-Line Pharmacologic Treatment

For abdominal pain refractory to first-line measures, tricyclic antidepressants (TCAs) are the preferred neuromodulator:

• Start amitriptyline 10 mg once daily at bedtime, titrating slowly to maximum 30-50 mg daily 2
• TCAs are superior to SSRIs for abdominal pain based on meta-analysis data 2
• Explain clearly that these are used as "gut-brain neuromodulators" for pain, not for depression, to improve adherence 2
• TCAs may serendipitously help diarrhea by prolonging gut transit time 2

If TCAs fail or are not tolerated:

• SSRIs are second-line neuromodulators for global symptoms 2
• If mood disorder coexists, use therapeutic-dose SSRI rather than low-dose TCA, as low doses won't adequately treat depression 2
• SNRIs (duloxetine) may be considered, particularly with psychological comorbidity, though RCT evidence in functional pain is limited 2

Dietary Interventions

• Low FODMAP diet as second-line dietary therapy should be supervised by trained dietitian with systematic reintroduction 2
• Do NOT recommend IgG-based food elimination diets—these lack evidence 2
• Gluten-free diet is not recommended for functional abdominal pain 2
• Probiotics may be tried for 12 weeks, but no specific strain can be recommended; discontinue if no benefit 2

Psychological Interventions

• Cognitive behavioral therapy, gut-directed hypnotherapy, and relaxation techniques are effective for chronic functional pain, especially in severe/refractory cases 2, 1
• Screen for risk factors for chronic pain: prior chronic pain, early adversity, trauma, poor coping styles, anxiety, depression 1

Critical Pitfalls to Avoid

• Do NOT use opioids for chronic functional abdominal pain—they cause narcotic bowel syndrome, dependence, gut dysmotility, serious infection risk, and mortality 2
• Do NOT perform repetitive testing once functional diagnosis is established—this increases costs without benefit and reinforces illness behavior 3
• Avoid unregulated/unproven therapies, especially those incentivized by financial gain 2
• For severe refractory symptoms with psychological comorbidity, consider combination neuromodulators (augmentation) but monitor for serotonin syndrome (fever, hyperreflexia, tremor, sweating, diarrhea) 2

When to Refer

• Refer to gastroenterology when symptoms are refractory to first-line treatments or patient requests specialist opinion 2
• Consider colonoscopy only if: alarm symptoms present, or in diarrhea-predominant symptoms with atypical features (age ≥50, female, autoimmune disease, nocturnal/severe watery diarrhea, weight loss, NSAID/PPI use) to exclude microscopic colitis 2
• Severe or refractory cases require integrated multidisciplinary approach involving gastroenterology, pain management, and mental health services 2