What is the appropriate management for a patient with severe, sudden lower abdominal pain, possibly accompanied by fever, vomiting, or difficulty urinating, and with an uncertain diagnosis?

Management of Severe, Sudden Lower Abdominal Pain

For patients presenting with severe, sudden lower abdominal pain with uncertain diagnosis, immediately assess for life-threatening conditions requiring emergent intervention, then proceed with a step-up diagnostic approach beginning with focused clinical examination and progressing to CT imaging, while initiating resuscitation and analgesia within 30-60 minutes. 1, 2

Immediate Assessment for Life-Threatening Conditions

First, rule out conditions requiring immediate surgical intervention:

• Assess for peritoneal signs (abdominal rigidity, guarding) indicating perforated viscus or peritonitis requiring immediate surgical evaluation 1, 2
• Evaluate for pain out of proportion to physical findings - the hallmark of acute mesenteric ischemia, especially in elderly patients with cardiovascular disease, atrial fibrillation, or recent MI 2
• Check vital signs for shock (hypotension, tachycardia, oliguria, altered mental status) indicating ongoing organ failure requiring immediate resuscitation 1
• In patients >60 years, consider leaking abdominal aortic aneurysm 1
• In women of reproductive age, obtain beta-hCG before imaging to rule out ruptured ectopic pregnancy 1, 2

Critical Clinical Examination Elements

Perform targeted physical examination to narrow differential diagnosis:

• Document pain location, onset, duration, quality, severity, and radiation pattern 3, 4
• Assess for fever and tachycardia indicating systemic inflammation or infection 1
• Evaluate for specific signs:
  • Positive psoas sign, fever, or migratory pain to right lower quadrant suggests appendicitis 1
  • Vomiting before pain onset makes appendicitis unlikely 1
  • Left lower quadrant tenderness with fever suggests diverticulitis 1
• Perform urinalysis if patient can void - hematuria supports renal colic diagnosis (present in >80% of cases), though absence doesn't exclude it 1

Laboratory Testing

Obtain targeted laboratory studies based on clinical presentation:

• Complete blood count to assess for leukocytosis indicating infection or inflammation 3
• In suspected mesenteric ischemia, check lactate, amylase, and stool for occult blood 2
• Electrolyte panel to guide resuscitation 1
• Note that laboratory values may be normal despite serious infection, especially in elderly and immunocompromised patients 2

Imaging Strategy

Follow American College of Radiology recommendations based on pain location:

• For lower abdominal pain with uncertain diagnosis, CT abdomen/pelvis with IV contrast is the primary imaging modality (ACR rating 8/9) 1, 3
• CT has higher sensitivity and specificity than ultrasound for lower abdominal pathology 1
• Imaging may be deferred only in:
  • Classic triad of left lower quadrant pain, fever, and leukocytosis with suspected uncomplicated diverticulitis 1
  • Known history of diverticulitis with mild recurrent symptoms 1
• Imaging is especially critical in elderly patients with fever, as typical signs may be masked 2
• In pregnant patients with inconclusive ultrasound, MRI has 94% sensitivity and 96% specificity for appendicitis 1

Immediate Management

Initiate treatment while diagnostic workup proceeds:

• Provide analgesia within 30 minutes of assessment - intramuscular diclofenac 75mg is preferred (Grade A recommendation) 1
• For contraindications to NSAIDs, use morphine with antiemetic (cyclizine) 1
• Administer IV fluid resuscitation for all patients with acute abdomen 1
• Provide thromboprophylaxis with low-molecular-weight heparin 1
• Correct electrolyte abnormalities and anemia 1

Antibiotic Considerations

Reserve antibiotics for specific indications:

• Do NOT routinely administer antibiotics unless superinfection or intra-abdominal abscess is confirmed 1
• For confirmed intra-abdominal infections, provide broad-spectrum coverage against gram-negative aerobic/facultative bacilli, gram-positive streptococci, and obligate anaerobes 1
• For abscesses >3cm, combine percutaneous drainage with antibiotics 1
• Small abscesses <3cm may be treated with IV antibiotics alone, though recurrence risk is higher 1

Disposition Criteria

Admit immediately if:

• Pain unrelieved within 60 minutes of analgesia 1
• Signs of shock or sepsis present 1
• Peritoneal signs develop 1, 2
• Suspected appendicitis - all cases require admission 5

Outpatient management possible for:

• Uncomplicated diverticulitis with good response to treatment 5
• Renal colic with adequate pain control - follow up by telephone at 1 hour, instruct patient to strain urine and maintain high fluid intake 1

Special Population Considerations

Adjust approach for high-risk patients:

• In neutropenic patients, typical signs of sepsis may be masked leading to delayed diagnosis and high mortality 2
• Advanced age with accumulated risk factors (comorbidities, septic shock) carries very high mortality - actively discuss palliative care when operative treatment appears futile 1
• Mortality increases with every hour of delay in conditions like mesenteric ischemia 2

Diagnostic Laparoscopy

When imaging is inconclusive, diagnostic laparoscopy achieves definitive diagnosis in 86-100% of cases and allows immediate therapeutic intervention 1