What is the recommended clinical pathway for acute appendicitis?

Clinical Pathway for Acute Appendicitis

Establish a standardized clinical pathway involving surgeons, emergency physicians, radiologists, and infectious disease specialists to optimize diagnosis, treatment, and outcomes for acute appendicitis. 1

Initial Clinical Assessment and Risk Stratification

Use clinical scoring systems (Alvarado or Pediatric Appendicitis Score) combined with laboratory findings to stratify patients into low, intermediate, or high-risk categories. 1

• Low-risk patients (low clinical scores, CRP <60 g/L, WBC <12×10⁹/L): Consider discharge with close outpatient follow-up within 24 hours or observation with non-operative management 1
• Intermediate-risk patients: Proceed to diagnostic imaging 1
• High-risk patients (classic presentation with peritoneal signs): May proceed directly to surgery, though imaging is still recommended for all female patients and those >40 years 1

Diagnostic Imaging Protocol

For adults and children with intermediate-risk presentation, use ultrasound as first-line imaging, reserving CT or MRI for inconclusive ultrasound findings. 1

Imaging Algorithm:

• First-line: Ultrasound with graded compression technique for all patients with suspected appendicitis 1
• Second-line imaging when ultrasound is inconclusive:
  • Children: MRI preferred over CT to avoid radiation (sensitivity 97.4%, specificity 97.1%) 1
  • Adults <40 years: Low-dose CT with IV contrast only (no oral/rectal contrast) 1
  • Adults ≥40 years: Standard CT with IV contrast 1
  • Pregnant patients: MRI is the preferred second-line modality 1

Critical imaging findings to document: appendiceal diameter (≥7mm suggests appendicitis, >13mm suggests complicated disease), presence of appendicolith, perforation, abscess, or phlegmon 1, 2

Treatment Pathway Based on Imaging Findings

Uncomplicated Acute Appendicitis (No perforation, abscess, or appendicolith)

Two treatment options exist with distinct risk-benefit profiles:

Option 1: Laparoscopic Appendectomy (Standard approach)

• Preoperative antibiotics: Administer broad-spectrum antibiotics covering aerobic gram-negatives and anaerobes within 1 hour of diagnosis 1
  • Recommended regimens: Cefoxitin, cefotetan, or ampicillin-sulbactam 1
  • Alternative: Ceftriaxone + metronidazole 1, 3
• Timing: Perform appendectomy as soon as feasible, ideally within 12-24 hours 1
• Postoperative antibiotics: Discontinue within 24 hours for uncomplicated cases 1

Option 2: Non-Operative Management with Antibiotics

This approach is appropriate for selected patients who meet ALL criteria: CT-confirmed uncomplicated appendicitis, NO appendicolith on imaging, no sepsis, and patient acceptance of 14-31% recurrence risk at 1 year (up to 39% at 5 years). 3, 2

• Antibiotic regimen:
  • IV therapy for minimum 48 hours: Amoxicillin-clavulanate, OR ceftriaxone + metronidazole, OR piperacillin-tazobactam 1, 3, 2
  • Beta-lactam allergy: Ciprofloxacin + metronidazole OR moxifloxacin 3
  • Total duration: 7-10 days (transition to oral after 48 hours if improving) 1, 3
• Expected outcomes: Initial success 70-78%, but approximately one-third require appendectomy within 1 year 3, 2, 4
• Contraindications to non-operative approach: Appendicolith present, appendiceal diameter >13mm, mass effect, age >60 years, or duration of symptoms <24 hours 1, 2

Complicated Acute Appendicitis (Perforation, abscess, or peritonitis)

Immediate broad-spectrum IV antibiotics covering mixed aerobic-anaerobic flora are mandatory. 1

• Antibiotic regimens:
  • Piperacillin-tazobactam monotherapy 1, 2
  • OR combination: Ampicillin + gentamicin + metronidazole 1
  • OR ceftriaxone + metronidazole 1, 5
• Surgical approach:
  • Abscess or phlegmon present: Consider percutaneous drainage followed by interval appendectomy 6-8 weeks later 1
  • Diffuse peritonitis: Urgent laparoscopic or open appendectomy 1
  • Drain placement: Consider abdominal drainage for complicated cases with perforation/abscess 1
• Postoperative antibiotics: Continue for 3-5 days or until clinical improvement (afebrile, normalized WBC) 1
  • Early transition to oral antibiotics (after 48 hours) is safe and cost-effective 1

Special Population Considerations

Pediatric Patients

• Imaging: Ultrasound first-line; MRI (not CT) for inconclusive ultrasound 1
• Uncomplicated appendicitis: Antibiotics can be discussed as alternative (97% initial success, 14% recurrence) 3
• Complicated appendicitis: Postoperative antibiotics for <7 days total; early oral transition after 48 hours is safe 1
• No postoperative antibiotics needed for uncomplicated cases after appendectomy 1

Elderly Patients (≥65 years)

• Higher threshold for non-operative management due to increased perforation risk and atypical presentations 1
• Preoperative broad-spectrum antibiotics mandatory 1
• Postoperative antibiotics: None for uncomplicated cases; 3-5 days for complicated cases based on clinical criteria 1
• Perform appendectomy as soon as possible once diagnosis established 1
• Consider colonoscopy for patients >40 years with complicated appendicitis treated non-operatively to exclude malignancy 1

Critical Pitfalls to Avoid

• Do not discharge intermediate-risk patients without imaging – false-negative rates exist even with normal imaging 1
• Do not use CT as first-line in children – ultrasound or MRI should be attempted first 1
• Do not offer non-operative management if appendicolith is present – failure rates approach 40% 2
• Do not continue prophylactic antibiotics beyond 24 hours for uncomplicated appendicitis after surgery 1
• Do not assume normal appendix at surgery means no pathology – consider other diagnoses but removal of normal appendix remains controversial 1
• Ensure 24-hour follow-up for all discharged patients, even if by telephone 1

Treatment Failure and Re-evaluation

For patients not improving after 4-7 days of treatment, obtain repeat CT or ultrasound imaging and continue effective antibiotics while investigating extra-abdominal sources. 1

• Obtain aerobic and anaerobic cultures if persistent infection 1
• Consider diagnostic laparoscopy if imaging inconclusive 1
• Reassess for complications: abscess formation, wound infection, or alternative diagnoses 1