Appendicitis

Appendicitis is the acute or chronic inflammation of the vermiform appendix, which is a small, tubular structure attached to the cecum of the large intestine. It is one of the most common surgical emergencies and can lead to serious complications, including perforation, abscess formation, and peritonitis if not diagnosed and treated promptly.

Epidemiology

• Incidence: Approximately 5% of the general population will experience appendicitis during their lifetime. The peak incidence is in the second and third decades of life.
• Gender Disparity: Males are more commonly affected than females, with a male-to-female ratio of approximately 1.5:1.
• Seasonality: There may be seasonal variations, with increased incidence during the summer months.

Etiology

The etiology of appendicitis is multifactorial, often involving mechanical obstruction, infection, and ischemia:

1. Mechanical Obstruction:
   • Fecaliths: Hardened stool is the most common cause of obstruction.
   • Lymphoid Hyperplasia: Especially prevalent in children and adolescents.
   • Tumors: Rarely, tumors (benign or malignant) may obstruct the appendiceal lumen.
   • Foreign Bodies: Ingestion of non-digestible materials can lead to obstruction.
2. Infection:
   • Bacterial overgrowth occurs after obstruction, commonly involving:
     • Escherichia coli
     • Bacteroides fragilis
     • Enterococcus spp.
   • Infection can lead to further inflammation and necrosis.
3. Ischemia:
   • Elevated intraluminal pressure from obstruction can compromise blood supply to the appendix, leading to ischemic necrosis.

Pathophysiology

1. Obstruction: Leads to increased intraluminal pressure, impaired venous drainage, and bacterial proliferation.
2. Inflammatory Response: The inflammatory process is characterized by:
   • Infiltration of neutrophils and lymphocytes.
   • Production of inflammatory mediators (prostaglandins, cytokines).
   • Tissue edema and further ischemia.
3. Necrosis and Perforation: If untreated, the inflammatory process can progress to necrosis, leading to perforation and peritonitis.
4. Formation of Abscess: In some cases, localized infection leads to an appendiceal abscess.

Clinical Presentation

1. Symptoms:
   • Abdominal Pain:
     • Begins as vague periumbilical pain that migrates to the right lower quadrant (RLQ) over 12-24 hours.
     • Pain is often sharp and may be exacerbated by movement or cough.
   • Nausea and Vomiting: Common, usually occurring after the onset of pain.
   • Anorexia: Patients often exhibit a loss of appetite.
   • Fever: Low-grade fever (often between 37.5°C and 38.5°C) may develop.
2. Signs:
   • Tenderness: McBurney’s point tenderness is classic, located two-thirds of the distance from the umbilicus to the anterior superior iliac spine.
   • Rebound Tenderness: Pain upon release of pressure indicates peritoneal irritation.
   • Guarding: Involuntary muscle contraction in the abdomen due to pain.
   • Psoas Sign: Pain upon extension of the right hip suggests retrocecal appendicitis.
   • Obturator Sign: Pain upon internal rotation of the flexed right thigh suggests inflammation of the appendix.

Diagnostic Evaluation

1. Laboratory Tests:
   • Complete Blood Count (CBC): Leukocytosis is common, typically >10,000/mm³, with a left shift (increase in immature neutrophils).
   • C-Reactive Protein (CRP): Elevated levels correlate with the severity of inflammation.
   • Urinalysis: To rule out urinary tract infections and assess for hematuria or pyuria.
2. Imaging Studies:
   • Ultrasound:
     • Useful in children and pregnant women; can demonstrate an enlarged, non-compressible appendix, periappendiceal fluid, and increased blood flow.
   • CT Scan: Gold standard in adults. Typical findings include:
     • Enlarged appendix (diameter >6 mm).
     • Wall thickening (>2 mm).
     • Periappendiceal fluid or abscess.
     • Mesenteric lymphadenopathy.
   • MRI: Useful in pregnant patients to avoid radiation exposure.
3. Differential Diagnosis:
   • Ectopic pregnancy.
   • Ovarian torsion.
   • Gastroenteritis.
   • Mesenteric adenitis.
   • Diverticulitis.
   • Inflammatory bowel disease (Crohn’s disease).

Management

1. Surgical Treatment:
   • Appendectomy:
     • Open Appendectomy: Traditional method; performed through a right lower quadrant incision. Indicated for complicated cases or when laparoscopy is not feasible.
     • Laparoscopic Appendectomy: Minimally invasive approach preferred for uncomplicated appendicitis; involves the use of a camera and specialized instruments to remove the appendix. It results in less postoperative pain, shorter recovery times, and lower rates of surgical site infections.
2. Preoperative Care:
   • Fluid Resuscitation: Initiate IV fluids (e.g., normal saline or lactated Ringer’s solution) to maintain hydration and electrolyte balance.
     • Example Dosage: Adults typically receive 500-1000 mL IV bolus followed by maintenance fluids (typically 75-125 mL/hr).
   • Antibiotics:
     • Administer broad-spectrum intravenous antibiotics before surgery.
     • Common Regimens:
       • Piperacillin-tazobactam: 3.375 g IV every 6 hours.
       • Ceftriaxone: 1 g IV every 24 hours plus Metronidazole: 500 mg IV every 8 hours.
       • Clindamycin: 900 mg IV every 8 hours plus Ciprofloxacin: 400 mg IV every 12 hours for penicillin-allergic patients.
3. Postoperative Care:
   • Monitoring: Regular assessment for complications such as infection, abscess formation, and ileus.
   • Diet Advancement: Gradually resume oral intake as tolerated, typically starting with clear liquids and progressing to a regular diet as bowel function returns.
   • Antibiotics: Continue for 24-48 hours post-surgery in cases of perforation or abscess formation.
4. Complications:
   • Perforation: Occurs in approximately 20% of patients if treatment is delayed, leading to peritonitis and increased morbidity. Mortality rates can increase significantly in the elderly or those with comorbidities.
   • Abscess Formation: Can require drainage, either percutaneously or surgically, in cases of perforated appendicitis.
   • Ileus: A common postoperative complication; may be managed with nasogastric decompression and supportive care.
   • Bowel Obstruction: Adhesions from surgery can lead to post-operative bowel obstruction, particularly in open procedures.

Prognosis

The prognosis for appendicitis is generally excellent with timely intervention. The mortality rate is low in healthy individuals but can be significantly higher in older adults or those with significant comorbidities. The presence of complications such as perforation or abscess formation may increase the length of hospitalization and the need for further surgical interventions.