What red‑flag symptoms should I watch for with abdominal pain and what is the initial management for non‑urgent stomach pain?

Stomach Pain: Red Flags and Initial Management

For non-urgent stomach pain, begin with supportive care including IV fluids, antiemetics, and bowel rest, but immediately assess for red flag symptoms that require emergency intervention. 1

Red Flag Symptoms Requiring Emergency Evaluation

Immediate Life-Threatening Signs

• Severe pain out of proportion to physical examination findings strongly suggests acute mesenteric ischemia and requires urgent CT angiography 2, 3
• Peritoneal signs (guarding, rebound tenderness, rigid abdomen) indicate perforation or ischemia requiring emergency surgical consultation 2, 1, 3
• Hemodynamic instability (tachycardia, hypotension, fever) suggests bowel ischemia, perforation, or sepsis requiring immediate intervention 2, 1
• Abrupt or instantaneous onset of severe pain suggests vascular catastrophe such as aortic dissection or mesenteric ischemia 3

Critical Warning Signs

• Weight loss with rectal bleeding is highly suggestive of colorectal cancer, which causes 60% of large bowel obstructions 1, 4
• Abdominal distension with vomiting and absence of flatus has 85% sensitivity for bowel obstruction, especially with prior abdominal surgery 1, 3
• Nocturnal symptoms, rectal bleeding, or anemia exclude functional causes and mandate investigation 2
• Age >45-55 years with new-onset symptoms requires imaging to exclude malignancy 2, 4

Initial Assessment for Non-Urgent Pain

Essential History Elements

• Pain location guides differential diagnosis and imaging selection 3, 5
• Last bowel movement and passage of gas has 85% sensitivity for adhesive small bowel obstruction in patients with prior surgery 3
• Symptom duration and progression predict severity 3
• Associated symptoms: Colicky pain suggests obstruction; pain relieved by defecation suggests irritable bowel syndrome 2, 3

Physical Examination Priorities

• Vital signs assessment to detect fever, tachycardia (the most sensitive early warning sign), hypotension, or tachypnea 1, 3
• Abdominal examination for distension, tenderness patterns, peritoneal signs, and Murphy's sign 3
• Digital rectal examination to assess for masses, bleeding, or empty rectum (classic for sigmoid volvulus) 3

Critical pitfall: See the patient twice if severe acute pain persists despite normal initial labs or imaging, as serious pathology may not be immediately apparent 6

Laboratory Investigations for Non-Urgent Cases

First-Line Tests

• Complete blood count: Leukocytosis >14,000 suggests infection, ischemia, or inflammation 1, 4
• Metabolic panel: Low bicarbonate and elevated lactate indicate intestinal ischemia 2, 1
• Pregnancy test mandatory in all women of reproductive age before imaging 1, 3

Additional Tests Based on Clinical Suspicion

• Fecal calprotectin for inflammatory bowel disease in subacute/chronic pain 6
• Helicobacter stool antigen and celiac serology for chronic pain evaluation 6
• Lipase if pancreatitis suspected 4

Important caveat: Normal laboratory values do not exclude serious disease, especially in elderly patients who may present with atypical symptoms and normal white blood cell counts 1, 3

Imaging Algorithm for Non-Urgent Pain

Based on Pain Location

• Right upper quadrant: Ultrasonography first (81% sensitivity, 83% specificity for cholecystitis) 1, 3, 5
• Right or left lower quadrant: CT abdomen/pelvis with IV contrast (>95% sensitivity for appendicitis) 1, 3, 5
• Diffuse or nonlocalized pain: CT abdomen/pelvis with IV contrast changes diagnosis in 49% of cases and management in 42% 1, 3

Avoid Common Pitfalls

• Plain radiographs have limited diagnostic value and should not be routinely ordered 3, 5
• Do not delay imaging based on clinical impression alone, as CT changes diagnosis in approximately 50% of cases with nonspecific pain 1, 4
• Minimize radiation exposure in young patients by considering ultrasound first when appropriate 3, 5

Initial Management for Non-Urgent Pain

Supportive Care

• IV crystalloid fluids for hydration and visceral perfusion enhancement 2
• Nasogastric decompression if obstruction suspected 2
• Antiemetics for symptom control 2
• Bowel rest initially 2

When to Avoid Treatment

• Do not use antibiotics routinely for all abdominal pain; reserve for confirmed or highly suspected infection 1
• Avoid vasopressors when possible, as norepinephrine and epinephrine impair mucosal perfusion 2

Special Population Considerations

Elderly Patients (Age >60)

• Higher likelihood of malignancy, diverticulitis, and vascular causes 3
• May present with atypical symptoms and normal laboratory tests 1, 3
• Urgent CT imaging recommended to exclude pancreatic cancer and other malignancies 4

Functional Diagnosis (IBS)

• Can be safely diagnosed in general practice with typical symptoms, normal examination, and absence of red flags (weight loss, rectal bleeding, nocturnal symptoms, anemia) 2
• Supportive features: Female, age <45, history >2 years, frequent past attendance with non-GI symptoms 2
• Repetitive testing not recommended once functional diagnosis established 7