Acute appendicitis/psoas abscess/diverticular disease

Definition

Appendicitis is an acute inflammation of the vermiform appendix, typically due to luminal obstruction. Most common cause of acute abdomen requiring emergency surgical intervention.

Background

• Definition: Acute inflammation of the appendix.
• Most commonly caused by obstruction of the appendiceal lumen:
  • Fecalith in adults
  • Lymphoid follicular hyperplasia in children
• Obstruction leads to increased intraluminal pressure, causing visceral (periumbilical) pain initially.
• As inflammation worsens and irritates the parietal peritoneum, pain localizes to the right lower quadrant (RLQ).
• Definitive treatment is appendectomy.

Pathophysiology

• Primary mechanism: Luminal obstruction → ↑ intraluminal pressure → bacterial overgrowth → inflammation → potential perforation
  • Adults: fecaliths most common
  • Children: lymphoid hyperplasia most common
  • Other less common causes: tumors, parasites, foreign bodies
• Clinical progression:
  • Early stage (0–12 h): Visceral, periumbilical pain
  • Middle stage (12–24 h): Localized RLQ pain (parietal peritoneum involvement)
  • Late stage (>24 h): ↑ risk of perforation & generalized peritonitis

Clinical Features

• Pain pattern:
  • Initial periumbilical discomfort → migrates to RLQ (McBurney’s point)
  • Worsened by movement, coughing
  • Nausea/vomiting often follows onset of pain
• Anorexia: Very common, frequently the earliest symptom
• Fever: Typically low-grade; high fever raises suspicion for perforation
• Physical exam:
  • McBurney’s point tenderness (most sensitive)
  • Rovsing’s sign, Psoas sign, Obturator sign
  • Rebound tenderness, guarding, rigidity → signs of peritoneal irritation
• Atypical presentations:
  • Elderly: vague symptoms, often late presentation, higher perforation risk
  • Pregnancy: appendix displaced upward, can present with RUQ or flank pain
  • Retrocecal appendix: back/flank pain, minimal abdominal findings
  • Pelvic appendix: suprapubic pain, urinary symptoms, rectal tenderness

Diagnostics

• Laboratory tests:
  • CBC with differential: Leukocytosis (>10,000/μL), left shift
  • CRP, ESR: Elevated in most cases
  • Urinalysis: Typically normal (mild WBC/RBC possible but not significant)
  • β-hCG in women of childbearing age to rule out ectopic pregnancy
• Imaging:
  • Ultrasound: First-line in children/pregnancy
    • Non-compressible appendix >6 mm, target sign, periappendiceal fluid
  • CT Abdomen/Pelvis (with contrast): Gold standard in adults
    • Appendix >6 mm, wall thickening, fat stranding, ± appendicolith
• Alvarado score: clinical tool based on symptoms, exam findings, labs
  • ≥7: high probability
  • 5–6: intermediate
  • ≤4: low probability

Examination Signs in Appendicitis

Alvarado Score

• A clinical scoring system used to assess the likelihood of acute appendicitis.
• Components:
  
  • Migration of pain (1 point)
  • Anorexia (1 point)
  • Nausea/vomiting (1 point)
  • RLQ tenderness (2 points)
  • Rebound pain (1 point)
  • Fever (1 point)
  • Leukocytosis (2 points)
  • Left shift (1 point)
• Interpretation:
  
  • ≥7: High probability
  • 5-6: Intermediate
  • ≤4: Low probability

Treatment

• Initial management: NPO, IV fluids, analgesics, antiemetics, and antibiotics if indicated
• Antibiotics:
  • Simple (uncomplicated): Cefoxitin or Ceftriaxone + Metronidazole
  • Complicated: Broad-spectrum regimens (e.g., Piperacillin-tazobactam)
• Definitive treatment:
  • Surgery: Laparoscopic appendectomy (preferred) within 12–24 hours
  • Non-operative management: Selected uncomplicated cases (antibiotics only); ~40% recurrence rate at 5 years
• Complicated cases (e.g., perforation, abscess):
  • Emergency surgery if diffuse peritonitis or sepsis
  • Percutaneous drainage (abscess >3 cm)
  • Extended antibiotic coverage
  • Interval appendectomy (6–8 weeks) sometimes considered

Complications

• Perforation: ~36–48 hours after onset if untreated, leading to peritonitis
• Abscess formation: may require drainage and prolonged antibiotics
• Other: Adhesions, bowel obstruction, pylephlebitis

Differential Diagnosis

• Ectopic pregnancy
• Pseudoappendicitis
• Meckel diverticulum
• Diverticulitis (especially in elderly patients)
• Psoas abscess (in patients with a positive psoas sign)
• Inflammatory bowel disease
• Gastroenteritis
• Colon cancer
• Urolithiasis and renal colic
• Urinary tract infections

Prognosis

• Mortality in uncomplicated appendicitis <0.1%
• Perforated cases: mortality ~0.6%, but higher in elderly
• Negative appendectomy rate: 10–15%
• Recovery: 1–3 weeks depending on technique and complications

Psoas abscess

Diverticular disease