Acute Appendicitis Pathophysiology, Diagnosis, and Management

Introduction

Acute appendicitis is one of the most common surgical emergencies worldwide, characterized by inflammation of the vermiform appendix. It is a leading cause of abdominal pain that requires surgical intervention, affecting approximately 7–8% of the population during their lifetime. The condition occurs when the lumen of the appendix becomes obstructed, leading to bacterial overgrowth, increased intraluminal pressure, and subsequent inflammation. Although advances in diagnostic imaging and surgical techniques have improved outcomes, delayed diagnosis and treatment can result in severe complications such as perforation, peritonitis, or abscess formation.

This article explores the etiology, pathophysiology, clinical presentation, diagnostic methods, and treatment options for acute appendicitis, along with the latest updates in management strategies.

Etiology and Risk Factors

The exact cause of acute appendicitis is multifactorial, but obstruction of the appendiceal lumen is a key factor. Common causes include:

• Fecaliths (hardened stool)
• Lymphoid hyperplasia (often associated with viral infections)
• Foreign bodies
• Tumors
• Parasites (e.g., pinworm infections in children)

Risk factors for acute appendicitis include age (most common between 10–30 years), a low-fiber diet, family history of appendicitis, and male gender. Seasonal variations have also been observed, with a slightly higher incidence in summer months.

Pathophysiology

Obstruction of the appendiceal lumen leads to mucus accumulation, increased intraluminal pressure, and bacterial multiplication. As pressure builds, blood flow is compromised, resulting in ischemia and necrosis of the appendix wall. Without treatment, the appendix may perforate, causing peritonitis or localized abscess formation.

The inflammatory response is mediated by bacterial overgrowth, typically involving organisms like Escherichia coli and Bacteroides fragilis. The process can progress rapidly, with perforation occurring within 24–72 hours if untreated.

Clinical Presentation

The hallmark symptom of acute appendicitis is abdominal pain, which typically begins as a vague periumbilical discomfort and then localizes to the right lower quadrant (RLQ) at McBurney’s point. Other common symptoms include:

• Nausea and vomiting (often following the onset of pain)
• Low-grade fever
• Loss of appetite (anorexia)
• Constipation or diarrhea

On physical examination, tenderness and guarding in the RLQ are characteristic findings. Special signs such as Rovsing’s sign (pain in the RLQ when the left lower quadrant is palpated), Psoas sign, and Obturator sign may be present.

Diagnosis

The diagnosis of acute appendicitis relies on a combination of clinical evaluation, laboratory tests, and imaging studies.

1. Clinical Scoring Systems
   • Alvarado Score: Assesses symptoms, signs, and laboratory findings to estimate the probability of appendicitis.
   • Pediatric Appendicitis Score (PAS): Used for children with suspected appendicitis.
2. Laboratory Tests
   • Elevated white blood cell (WBC) count and C-reactive protein (CRP) levels are common but nonspecific indicators of inflammation.
3. Imaging
   • Ultrasound (US): Preferred for children and pregnant women due to its safety and high sensitivity.
   • Computed Tomography (CT): Gold standard for diagnosis in adults, especially in atypical presentations.
   • Magnetic Resonance Imaging (MRI): Used as an alternative in cases where radiation exposure is a concern.
     

Differential Diagnosis

Acute appendicitis must be differentiated from other causes of acute abdominal pain, including:

• Gastroenteritis
• Mesenteric lymphadenitis
• Ovarian cysts or torsion
• Pelvic inflammatory disease (PID)
• Renal colic
• Crohn’s disease

Management

The standard treatment for acute appendicitis is appendectomy, which can be performed via open surgery or laparoscopically. Early surgical intervention significantly reduces the risk of complications.

1. Surgical Management
   • Open Appendectomy: Traditional approach with an incision in the RLQ.
   • Laparoscopic Appendectomy: Minimally invasive, associated with faster recovery and reduced postoperative pain.
2. Non-Operative Management
   • Recent studies suggest that selected patients with uncomplicated appendicitis can be treated with antibiotics alone. However, recurrence rates and the need for subsequent surgery remain concerns.
3. Perforated Appendicitis
   • Requires prompt surgical drainage and broad-spectrum antibiotic therapy.

Postoperative Care and Complications

Post-surgical complications include wound infections, intra-abdominal abscesses, and postoperative ileus. Early mobilization, pain management, and careful monitoring of surgical wounds help minimize these risks.

Long-term outcomes are generally excellent, with most patients recovering fully within a few weeks.

Prevention and Public Health Considerations

While there are no definitive preventive measures for acute appendicitis, a diet high in fiber may reduce the risk by preventing constipation and fecalith formation. Early recognition of symptoms and timely access to healthcare are crucial in preventing complications.

Conclusion

Acute appendicitis remains a significant clinical challenge despite advances in diagnostics and treatment. Prompt diagnosis based on clinical evaluation, supported by imaging and laboratory tests, is key to effective management. While appendectomy remains the gold standard treatment, non-operative management with antibiotics is emerging as an alternative in carefully selected cases. Continued research into diagnostic tools and minimally invasive therapies is expected to further improve patient outcomes.

References

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2. Humes DJ, Simpson J. Acute appendicitis. BMJ. 2006;333(7567):530–534.
3. Di Saverio S, Podda M, De Simone B, et al. Diagnosis and treatment of acute appendicitis: 2020 update of the WSES Jerusalem guidelines. World J Emerg Surg. 2020;15:27.
4. Raja AS, Wright C, Sodickson AD, et al. Negative appendectomy rate in the era of CT: an 18-year perspective. Radiology. 2010;256(2):460–465.
5. Salminen P, Paajanen H, Rautio T, et al. Antibiotic therapy vs appendectomy for treatment of uncomplicated acute appendicitis: The APPAC randomized clinical trial. JAMA. 2015;313(23):2340–2348.