What is the initial management and evaluation for a patient presenting with abdominal pain?

Initial Management and Evaluation of Abdominal Pain

The initial management of abdominal pain should include a focused history, physical examination, complete blood count, and targeted imaging based on pain location, with contrast-enhanced CT scan of the abdomen and pelvis being the first-line imaging modality for nonlocalized abdominal pain due to its near 100% sensitivity for many common causes. 1

Initial Assessment

History

• Pain characteristics: onset, location, radiation, quality, severity, timing, aggravating/alleviating factors
• Associated symptoms: fever, nausea, vomiting, diarrhea, constipation, urinary symptoms
• Past medical history: previous surgeries, chronic conditions
• Medication history: focus on NSAIDs, antibiotics, steroids, immunosuppressants
• For women of reproductive age: last menstrual period and pregnancy status 1

Physical Examination

• Vital signs: assess for fever, tachycardia, hypotension (signs of sepsis)
• Abdominal examination:
  • Inspection: distension, visible peristalsis, surgical scars
  • Auscultation: bowel sounds (hyperactive, hypoactive, absent)
  • Palpation: tenderness, guarding, rebound tenderness, rigidity
  • Percussion: tympany, dullness, shifting dullness (ascites)
  • Rectal examination: masses, tenderness, blood 1, 2

Laboratory Tests

• Complete blood count (CBC): assess for leukocytosis, anemia
• Basic metabolic panel: electrolyte abnormalities, renal function
• Liver function tests: for suspected hepatobiliary disease
• Lipase/amylase: for suspected pancreatitis
• Urinalysis: for UTI, nephrolithiasis
• Pregnancy test (β-hCG): in all women of reproductive age before imaging 1

Imaging Based on Pain Location

1. Nonlocalized abdominal pain:

   • Contrast-enhanced CT abdomen and pelvis (first-line) 1

2. Right upper quadrant pain:

   • Ultrasonography (first-line): 88% sensitivity, 80% specificity for acute cholecystitis 1

3. Right lower quadrant pain (suspected appendicitis):

   • CT abdomen and pelvis (first-line in adults): 97% sensitivity, 94% specificity
   • Ultrasound preferred in children and pregnant patients 1

4. Left lower quadrant pain (suspected diverticulitis):

   • CT abdomen and pelvis (first-line): 81% sensitivity 1

5. Suspected urolithiasis:

   • Non-contrast CT abdomen and pelvis: 97-100% sensitivity 1

6. Suspected gynecologic etiology:

   • Transvaginal ultrasound (first-line) 1

Special Populations

Pregnant Patients

• Ultrasound first, followed by MRI if inconclusive (to avoid radiation) 1

Elderly Patients

• Lower threshold for CT imaging as clinical signs may be unreliable
• Higher risk for serious pathology and surgical emergencies 1

Immunocompromised Patients

• Lower threshold for advanced imaging
• May present with atypical symptoms
• Higher risk for serious pathology and intra-abdominal abscess 1

Red Flags Requiring Immediate Attention

• Peritoneal signs (rebound tenderness, guarding)
• Bowel obstruction
• Suspected appendicitis
• Perforated viscus
• Mesenteric ischemia
• Abdominal aortic aneurysm
• Adnexal torsion
• Ruptured ectopic pregnancy 1

Management of Intra-abdominal Infections

Initial Resuscitation

• Prompt administration of intravenous fluids is critical
• Resuscitation should be titrated to clinical response
• Vasopressors may be needed when fluid therapy alone is failing 3

Antibiotic Therapy

• Initiate once intra-abdominal infection is diagnosed or strongly suspected
• For stable, non-immunocompromised patients: Amoxicillin/Clavulanate 2g/0.2g every 8 hours
• For critically ill patients: Piperacillin/tazobactam 6g/0.75g loading dose then 4g/0.5g every 6 hours 1

Management of Abscesses

• Small abscesses (<3 cm): intravenous antibiotics (risk of recurrence) 3
• Abscesses >3 cm: percutaneous drainage plus antibiotics 3, 1
• Surgery if percutaneous drainage fails or signs of septic shock persist 3

Pain Management

• Multimodal analgesia with scheduled acetaminophen and NSAIDs as first-line
• Avoid prolonged opioid use when possible 1
• Early administration of analgesia does not impair diagnostic accuracy 4

Specific Conditions

Inflammatory Bowel Disease (IBD)

• Multidisciplinary approach involving gastroenterologist and surgeon
• Adequate IV fluids, thromboprophylaxis, correction of electrolyte abnormalities
• Antibiotics only if superinfection or abscess is present
• For severe active ulcerative colitis: IV corticosteroids (if hemodynamically stable) 3

Mesenteric Ischemia

• Surgical revascularization for patients with peritoneal signs and evidence of bowel infarction
• Angiography with possible percutaneous intervention for patients without peritoneal signs
• Systemic anticoagulation as adjunctive therapy 3

Common Pitfalls to Avoid

1. Delaying imaging in elderly patients (may present atypically)
2. Missing gynecologic causes in women of reproductive age
3. Inadequate pain control leading to unnecessary suffering
4. Overlooking serious pathology in immunocompromised patients
5. Failing to recognize sepsis early 1

Remember that the acute abdomen carries a 2% to 12% mortality rate, with mortality increasing for every hour until specific treatment is provided. Structured, rapid, and targeted diagnosis and treatment markedly lower morbidity and mortality 5.