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Acute Appendicitis

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1. Classification

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2. Clinical Presentation

Symptoms

• Classic triad: periumbilical pain migrating to the right iliac fossa (RIF) over 6–12 h + nausea/vomiting + anorexia
• Pain is continuous, worsens with movement; patient prefers to lie still
• Low-grade fever (37.5–38.5 °C); high fever suggests perforation or abscess
• Nausea, vomiting, constipation (or diarrhea in pelvic appendicitis)

Physical Signs

Atypical Presentations

• Retrocecal appendix (~65%): vague flank/back pain, psoas sign positive
• Pelvic appendix: urinary frequency, rectal tenderness, diarrhea
• Subhepatic appendix: RUQ pain mimicking cholecystitis
• Elderly patients: blunted signs, frequently present late with perforation
• Pregnant women: appendix displaced superiorly; pain in RUQ by 3rd trimester
• Children: higher perforation rate due to diagnostic delay and thin omentum

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3. Diagnosis

Scoring Systems

• ≤4: appendicitis unlikely → observe/discharge
• 5–6: equivocal → imaging required
• 7–10: high probability → operate or confirm with CT

Laboratory Findings

• Leukocytosis (WBC >10,000/µL) in ~80%; left shift (neutrophilia)
• CRP elevated (>10 mg/L) — rises later (6–12 h); combination of WBC + CRP increases sensitivity
• Urinalysis: mild pyuria/hematuria (5–25%) from ureteral proximity — does not exclude appendicitis
• Serum β-hCG in women of childbearing age (exclude ectopic pregnancy)

Imaging

• First-line in children and pregnant women
• Findings: non-compressible, blind-ending tubular structure >6 mm outer diameter, absent peristalsis, periappendiceal fluid
• Sensitivity ~75–90%, specificity ~85–95%
• Operator-dependent; limited by obesity and gas

• Sensitivity 94–98%, specificity 95–99%
• Findings:
  • Appendiceal diameter >6 mm (thickened wall, lumen distension)
  • Periappendiceal fat stranding
  • Arrowhead sign (oral contrast funnel at cecal base pointing to occluded orifice)
  • Appendicolith (calcified fecalith)
  • Phlegmon or abscess in perforated cases

• Preferred in pregnant women when US is inconclusive
• No radiation; sensitivity and specificity comparable to CT

Per ACEP guidelines, clinical prediction rules (e.g., Alvarado) can identify low-risk patients who may not require advanced imaging, but imaging (CT or US) remains the standard for equivocal cases.

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4. Management

Non-Operative (Conservative) Management

• Antibiotics-first strategy (APPAC trial, CODA trial) is a validated option for uncomplicated acute appendicitis in selected adults
• Regimen: IV piperacillin-tazobactam or IV amoxicillin-clavulanate → oral antibiotics (5–10 days)
• ~70% success at 1 year; ~30% will eventually require appendectomy
• Not recommended for: perforated appendicitis, appendicolith, high-risk patients

Operative Management (Standard of Care)

• Appendectomy remains the definitive treatment
• Pre-operative: IV fluids, broad-spectrum antibiotics (cover gram-negatives and anaerobes), analgesia, NPO
• Antibiotic prophylaxis: cefazolin + metronidazole (or piperacillin-tazobactam)

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5. Surgical Approaches

Open Appendectomy (Laparotomy)

• McBurney incision: oblique incision over McBurney's point (RIF) — classic approach
• Lanz incision: transverse RIF incision — better cosmesis
• Lower midline / right paramedian incision: used when diagnosis is uncertain or diffuse peritonitis is present

Laparoscopic Appendectomy (Preferred in Most Centers)

• Less postoperative pain
• Shorter hospital stay
• Faster return to normal activity
• Lower wound infection rate
• Better visualization for obese patients and uncertain diagnoses (Harrison's, p. 9193)

• Higher incidence of intraabdominal abscess post-perforation (some studies)
• Requires general anesthesia (cannot be done under spinal)
• Longer OR time

Single-Incision Laparoscopic Surgery (SILS) / NOTES

• Experimental/specialized centers; cosmetically superior, no clear outcomes benefit

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6. Types of Anesthesia

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7. Indications for Drainage and Tamponade of the Abdominal Cavity

Periappendiceal Abscess

• Percutaneous CT/US-guided drainage: first-line for well-defined abscess (>3 cm)
• Followed by interval appendectomy 6–8 weeks later (though this is debated — some do not require interval appendectomy if no appendicolith)
• IV antibiotics as bridge therapy

Intraoperative Drainage Indications

• Localized peritonitis with abscess: drain placed at time of appendectomy
• Perforated appendicitis with contamination: thorough peritoneal lavage (warm saline 3–5 L), suction drainage
• Ongoing soilage / complex phlegmon: closed-suction drain (e.g., Jackson-Pratt) left in the abscess cavity

Tamponade (Gauze Packing / Omental Tamponade)

• Used when bleeding from the mesoappendix or appendiceal bed cannot be fully controlled
• Omental packing used to wall off a necrotic/phlegmonous base that cannot be safely resected (rare)
• "Damage control" approach in severely unstable patients: pack and re-look in 24–48 h
• Indications:
  1. Uncontrolled hemorrhage from the mesoappendix/cecal base
  2. Severe fecal contamination requiring staged laparotomy
  3. Diffuse gangrenous peritonitis with hemodynamic instability — pack, close, ICU resuscitation, re-operation

Peritoneal Lavage

• Performed in diffuse peritonitis (Grade IVb): copious irrigation with warm saline to reduce bacterial load
• Controversial in localized perforation: lavage may spread contamination

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8. Complications of Acute Appendicitis

Early Complications

Postoperative Complications

Chronic / Long-term Complications

• Adhesive intestinal obstruction (small bowel obstruction from adhesions)
• Infertility in women (right-sided pelvic adhesions following perforation)
• Hernia at incision site (especially McBurney)
• Chronic right iliac fossa pain / "stump appendicitis"

Mortality

• Uncomplicated appendicitis: 0.1–0.5% (approximates the risk of general anesthesia alone)
• Perforated appendicitis: 3% overall, up to 15% in the elderly (Harrison's, p. 9193)

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Summary Algorithm

Suspected Acute Appendicitis
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Clinical assessment + Alvarado score
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Score ≥7 → Operate (or CT to confirm)
Score 4–6 → CT scan
Score ≤3 → Observe / alternative diagnosis
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Imaging confirms appendicitis?
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Uncomplicated → Laparoscopic appendectomy (or antibiotics if patient chooses)
Perforated + abscess → Percutaneous drainage + interval appendectomy
Perforated + diffuse peritonitis → Emergency appendectomy + peritoneal lavage ± drain

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