What is the recommended treatment for chronic abdominal pain?

Treatment of Chronic Abdominal Pain

For chronic abdominal pain, initiate low-dose tricyclic antidepressants (starting at 10 mg amitriptyline once daily, titrating to 30-50 mg) as first-line pharmacotherapy after ruling out organic disease, combined with behavioral interventions including relaxation training and cognitive-behavioral therapy. 1

Initial Diagnostic Approach

• Rule out organic disease first by assessing for alarm features including nocturnal symptoms, unintentional weight loss, fever, rectal bleeding, and family history of gastrointestinal malignancy 1

• Identify abdominal wall pain using Carnett's test (pain that worsens with abdominal wall tensing suggests abdominal wall origin rather than visceral pain), as this represents 2-3% of chronic abdominal pain cases but up to 30% in patients with previously undiagnosed chronic pain 2

• Assess for neuropathic features, particularly allodynia (pain from normally non-painful stimuli like food in stomach or urge to defecate), which is present in 81% of patients with chronic continuous abdominal pain 3, 1

• Screen for risk factors that predict transition to chronic pain: prior chronic pain history, early-life trauma or adversity, poor coping styles (catastrophizing), pre-existing anxiety/depression, and negative prior pain experiences 1

First-Line Pharmacologic Treatment

Tricyclic antidepressants are the most effective first-line neuromodulator for chronic abdominal pain with strong evidence 1:

• Start amitriptyline 10 mg once daily at bedtime
• Titrate slowly every 2-3 weeks to maximum 30-50 mg once daily
• Explain to patients this targets pain modulation in the brain and spinal cord, not depression
• Lower doses often suffice compared to psychiatric indications 1

Alternative neuromodulators if tricyclics are not tolerated 1:

• Serotonin-norepinephrine reuptake inhibitors (SNRIs) like duloxetine (most effective SNRI based on cohort data) 3
• Mirtazapine as third option
• Selective serotonin reuptake inhibitors (SSRIs) have weaker evidence but may help global symptoms 1

Combination Therapy for Refractory Pain

Combination neuromodulators are superior to monotherapy for severe or refractory chronic abdominal pain 1, 3:

• Duloxetine plus gabapentin is an effective combination
• Monitor for serotonin syndrome when combining SSRIs with SNRIs (symptoms: fever, hyperreflexia, tremor, sweating, diarrhea) 1
• Reserve mood stabilizers (gabapentin, valproic acid) and atypical antipsychotics for psychiatric consultation only 1

Non-Pharmacologic Interventions

Behavioral therapies should be initiated early alongside medications 1:

• Relaxation training and breathing techniques to reduce autonomic arousal related to pain 1
• Cognitive-behavioral therapy for patients with insight into how thoughts/feelings relate to pain 1
• Gut-directed hypnotherapy for visceral hypersensitivity (avoid in severe PTSD) 1
• Exercise and physical activity to offset negative consequences of pain-related inactivity 1
• Mindfulness-based stress reduction teaches nonjudgmental observation of pain 1

Critical Pitfalls to Avoid

Avoid opioids at all costs - they cause narcotic bowel syndrome (chronic worsening pain despite escalating opioid doses due to hyperalgesia), invalidate motility testing, and increase infection risk 1:

• Opioid use is associated with allodynia development (p=0.003) 3
• If already on opioids, use clonidine for withdrawal symptoms and peripheral mu-opioid antagonists 1
• Replace with neuropathic pain medications during controlled dose reduction 1

Avoid unnecessary surgery - prior surgery predicts further operations but surgery does not resolve chronic abdominal pain and worsens pain in 35% of cases 3:

• Surgery should only be considered after exhausting medical management
• Multiple laparotomies can cause secondary dysmotility from adhesions 1

Avoid cyclizine for long-term use - causes addictive behavior and vein damage, especially intravenously 1

Specific Conditions

For IBS-related chronic abdominal pain 1:

• Soluble fiber (ispaghula 3-4 g/day, gradually increased) for first-line treatment
• Avoid insoluble fiber (wheat bran) which exacerbates symptoms
• Certain antispasmodics may help but have limited evidence
• Low FODMAP diet as second-line dietary therapy (requires dietitian supervision)

For abdominal wall pain specifically 2:

• Inject local anesthetic (lidocaine) into painful area - provides 4-week relief in 95% when combined with steroids
• Lidocaine alone effective in 83-91%
• Long-term relief after single injection in 20-30%, after repeated injections in 40-50%
• Neurectomy for refractory cases

Multidisciplinary Management

Refer to pain psychology early for patients with 1:

• Severe or refractory symptoms despite initial interventions
• Significant psychiatric comorbidities (anxiety, depression requiring higher SSRI/bupropion doses per FDA guidelines) 1
• Pain catastrophizing or poor coping mechanisms
• History of trauma or substance misuse

Avoid referral to surgery unless clear structural pathology identified, as this leads to iatrogenic harm in chronic pain patients 1, 3