Appendicitis

Detailed Overview

The condition begins with obstruction of the appendiceal lumen. This obstruction leads to fluid stasis, bacterial overgrowth, and inflammation. As pressure builds within the appendix, it compresses venous and lymphatic drainage, causing wall ischemia and necrosis. If surgical removal (appendectomy) is not performed promptly, the ischemic wall will perforate, spilling infected fecal matter into the peritoneal cavity. This transforms a localized infection into generalized peritonitis, significantly increasing morbidity and mortality. Presentation classically involves migratory pain, moving from the umbilicus to the right lower quadrant.

Epidemiology & Demographics

Lifetime risk is approximately 7-8%. It is most common in the second and third decades of life (ages 10-30), with a slight male predominance (1.4:1).

Etiological Mechanism

The primary etiology is luminal obstruction. In adults, this is most commonly caused by a fecalith (a hard piece of stool). In children and adolescents, lymphoid hyperplasia (often following a viral infection) is the most frequent cause. Rare causes include foreign bodies, tumors (carcinoid), or parasites (Ascaris lumbricoides).

Primary Causes

Fecalith (Hardened stool)

Lymphoid Hyperplasia

Foreign Bodies

Neoplasm

• Age: Peak incidence in teens and young adults.
• Low-fiber diet: May contribute to the formation of fecaliths, common in Western populations.
• Recent Gastrointestinal Infection: Causes lymphoid hyperplasia in the gut lining.

1. The narrow appendiceal lumen becomes obstructed. 2. The appendiceal mucosa continues to secrete mucus, causing rapid distension and an increase in intraluminal pressure. 3. Visceral afferent nerve fibers are stretched, causing diffuse, poorly localized periumbilical pain. 4. Resident gut flora (E. coli, Bacteroides fragilis) rapidly multiply within the stagnant fluid. 5. Increased pressure exceeds venous pressure, causing venous congestion, edema, and ischemia. 6. The inflammatory process extends to the serosa and the adjacent parietal peritoneum. This shifts the pain to a sharp, localized somatic pain in the right lower quadrant. 7. Arterial thrombosis occurs, leading to gangrene and eventual perforation.

Characteristic Clinical Presentation

• Migratory Abdominal Pain: Classically starts as a dull ache around the belly button, then moves to the right lower abdomen over 12-24 hours and becomes sharp.
• Anorexia: Loss of appetite is nearly universal. If a patient is hungry, suspect another diagnosis.
• Nausea and Vomiting: Typically begins AFTER the onset of pain (unlike gastroenteritis, where vomiting often precedes pain).

Physical Examination Signs

• McBurney's Point Tenderness
• Rovsing's Sign
• Psoas Sign

• Perforation/Peritonitis: Rupture spilling bacteria into the abdomen; risk increases significantly after 48 hours of symptoms.
• Appendiceal Abscess: The body walls off the perforation with omentum and bowel loops, forming a localized pocket of pus.
• Pylephlebitis: Rare, fatal infective thrombosis of the portal vein.

Diagnostic Criteria & Guidelines

Clinical diagnosis often aided by scoring systems like the Alvarado Score (MANTRELS). Imaging confirms the diagnosis, especially when clinical presentation is atypical.

Differential Diagnosis

• Ectopic Pregnancy (in females)
• Ovarian Torsion or Ruptured Cyst
• Crohn's Disease (terminal ileitis)
• Mesenteric Adenitis (in children)
• Right-sided Ureteral Stone

Laboratory Tests & Biomarkers

• Complete Blood Count: Mild leukocytosis (10,000 - 18,000/mcL) with a left shift (predominance of neutrophils).
• Urinalysis: Usually normal. Mild pyuria/hematuria can occur if the inflamed appendix rests on the bladder or ureter.
• Pregnancy Test (Beta-hCG): Mandatory in all females of childbearing age to rule out ectopic pregnancy.

Imaging Modalities & Findings

• CT Abdomen/Pelvis with IV Contrast: Highly sensitive and specific in adults. Shows an enlarged appendix (>6 mm diameter), appendiceal wall thickening, periappendiceal fat stranding, and potentially an obstructing appendicolith.
• Abdominal Ultrasound: Preferred first-line imaging in children and pregnant women to avoid radiation. Shows a non-compressible, thick-walled appendix.

• Early/Simple
  Inflamed but intact appendix. Can sometimes be managed with antibiotics alone in select adults.
• Gangrenous
  Ischemic necrosis of the appendiceal wall has begun, impending rupture.
• Perforated
  The appendix has burst, causing localized abscess or generalized peritonitis. Requires longer hospital stay and IV antibiotics.

Second-Line & Adjunctive Therapy

For patients with an established Appendiceal Abscess (delayed presentation >3 days): Non-operative management initially with IV antibiotics and CT-guided percutaneous drainage of the abscess. Interval appendectomy may be performed 6-8 weeks later.

Surgical & Procedural Management

Laparoscopic appendectomy is the gold standard, offering less pain, faster recovery, and lower wound infection rates compared to open appendectomy.

Recommended Lifestyle Changes

• No specific preventative lifestyle changes, though a high-fiber diet is theoretically protective.
• Post-operatively: Avoid heavy lifting (>10 lbs) for 2-4 weeks.

Patient Counseling & Advice

Explain the importance of early surgical intervention to prevent rupture. Inform them that the appendix has no essential function in adults, and living without it has no negative consequences.

Follow-Up & Monitoring Schedule

Outpatient surgical follow-up in 2-3 weeks to check the port-site incisions and review pathology results (to rule out unexpected neuroendocrine tumors).

Preventive Strategies

No proven primary prevention strategies.

Excellent. Mortality for non-perforated appendicitis is < 0.1%. Mortality rises to up to 5% in the elderly with perforated appendicitis.