What causes nocturnal abdominal pain?

Nocturnal Abdominal Pain: Differential Diagnosis and Clinical Approach

Nocturnal abdominal pain should prompt immediate consideration of duodenal ulcer disease, which causes pain several hours after eating and often at night, with 63% of duodenal ulcer patients experiencing nocturnal symptoms. 1

Key Diagnostic Considerations

Classic Peptic Ulcer Disease Pattern

• Duodenal ulcers characteristically cause epigastric pain that awakens patients at night, typically 2-5 hours after eating when the stomach is empty 2, 1
• Hunger provokes the pain in most cases, and eating often provides relief 2
• While 63% of duodenal ulcer patients experience nocturnal pain, this symptom has only 50% specificity, meaning other conditions also present nocturnally 1
• The combination of well-localized epigastric pain AND nocturnal occurrence has 96% specificity for duodenal ulcer, though only 9% sensitivity 1

Other Gastrointestinal Causes

• Gastroesophageal reflux disease (GERD) can cause nocturnal epigastric pain, heartburn, and regurgitation when patients are supine 2
• Chronic pancreatitis produces pain that radiates to the back and may worsen at night 2
• Irritable bowel syndrome (IBS) can present with nocturnal symptoms, including nocturnal diarrhea or abdominal pain, which are considered atypical features warranting further investigation 3

Critical Red Flag Conditions

Life-threatening causes must be excluded first, as certain conditions presenting with nocturnal abdominal pain carry extremely high mortality:

• Mesenteric ischemia presents with pain out of proportion to physical examination findings and carries 30-90% mortality 4
• Aortic dissection causes severe abdominal pain with abrupt onset when involving the abdominal aorta 4
• Ruptured abdominal aortic aneurysm presents with severe abdominal and back pain, often with hypotension, and has >50% mortality even with prompt intervention 4

Inflammatory Bowel Disease Considerations

• Crohn's disease and ulcerative colitis can cause nocturnal abdominal pain during disease flares, with 50-70% of IBD patients experiencing pain during active disease 3
• Nocturnal symptoms in IBD may indicate active inflammation requiring optimization of therapy 3
• Faecal incontinence occurs at night in older IBD patients or those with ileo-anal anastomosis surgery 3

Rare but Important Causes

• Spinal cord compression from malignancy (e.g., Burkitt's lymphoma) can manifest initially as nocturnal abdominal pain before neurological symptoms develop 5
• Adult-onset cystic fibrosis may present with recurrent nocturnal abdominal pain and pancreatitis 6

Diagnostic Approach

Initial Clinical Assessment

Focus on pain characteristics that distinguish causes:

• Timing relative to meals: Duodenal ulcer pain occurs 2-5 hours post-meal; gastric ulcer pain occurs immediately after eating 2
• Pain location: Single-finger localization to epigastrium suggests duodenal ulcer (13% sensitivity, 92% specificity) 1
• Relationship to defecation: Pain relief with bowel movements suggests IBS 2
• Radiation pattern: Back radiation suggests pancreatitis or aortic pathology 4, 2

Red Flags Requiring Urgent Evaluation

• Pain out of proportion to examination findings (mesenteric ischemia) 4
• Abrupt onset of severe pain (aortic dissection) 4
• Associated hypotension or hemodynamic instability 4
• Progressive neurological symptoms (spinal pathology) 5
• Weight loss, fever, or signs of systemic illness 3

Imaging Strategy

CT abdomen and pelvis with IV contrast is the preferred initial imaging for nonlocalized acute abdominal pain with fever or concerning features 3

• CT angiography is the gold standard for diagnosing mesenteric ischemia and aortic pathologies 4
• Ultrasonography is preferred for right upper quadrant pain (biliary disease) 3
• Plain radiographs have limited diagnostic value and should not delay definitive imaging 3

Laboratory Evaluation

• Complete blood count, comprehensive metabolic panel, lipase for pancreatitis 3
• Consider testing for Helicobacter pylori in suspected peptic ulcer disease 2
• Beta-hCG in women of reproductive age before imaging 3

Management Priorities

Immediate Actions for High-Risk Presentations

• Mesenteric ischemia requires immediate surgical consultation and often emergent revascularization through embolectomy or bypass grafting 4
• Type A aortic dissection requires immediate surgical intervention; type B dissections are managed medically with blood pressure control 4
• Severe acute pancreatitis requires intensive care monitoring and aggressive fluid resuscitation 4

Treatment of Common Causes

• Duodenal ulcer: Proton pump inhibitors and H. pylori eradication if present 2
• GERD: Proton pump inhibitors, lifestyle modifications including head-of-bed elevation 2
• IBD-related pain: Optimize anti-inflammatory therapy; consider tricyclic antidepressants as adjuvant analgesics; avoid opioids due to risk of dependence, narcotic bowel syndrome, and increased mortality 3

Special Considerations

• In adult-onset cystic fibrosis with recurrent nocturnal abdominal pain, nocturnal hydration is a simple, cost-effective preventive measure 6
• Microscopic colitis should be considered in patients with nocturnal diarrhea, particularly those >50 years, female, or taking NSAIDs, PPIs, or SSRIs 3
• Functional dyspepsia and IBS may manifest with nocturnal symptoms (41% and 58% respectively), but diagnosis requires exclusion of organic pathology 1

The absence of both localized pain and nocturnal occurrence makes duodenal ulcer unlikely (93% negative predictive value), but their presence requires endoscopic confirmation as specificity remains limited. 1