Appendicitis

Appendicitis: Anatomy & Etiopathogenesis - Gut's Grumpy Nook

• Anatomy Essentials:
  • True diverticulum of caecum; base at confluence of 3 taeniae coli.
    • 📌 Mnemonic: "Taeniae meet At The Appendix base."
  • Surface marking: McBurney's point (junction of lateral ⅓ & medial ⅔, umbilicus to ASIS line).
  • Most common position: Retrocaecal (~65-70%). Others: pelvic, subcaecal, pre/post-ileal.
  • Blood supply: Appendicular artery (end-artery from ileocolic artery).
  • Innervation: Sympathetic & visceral afferents via T10 (initial periumbilical pain).
• Etiopathogenesis:
  • Core mechanism: Luminal obstruction.
    • Adults: Fecolith (most common).
    • Children: Lymphoid hyperplasia (most common).
    • Others: Parasites (e.g., Ascaris), carcinoid tumor, foreign body, strictures.
  • Pathophysiology Cascade:

*   ![Anatomy of the appendix and surrounding structures](https://ylbwdadhbcjolwylidja.supabase.co/storage/v1/object/public/notes/L1/Surgery_Gastrointestinal_Surgery_Appendicitis/3f12c452-bf96-4a7c-8b4a-24514bd2ff6e.jpg)
> ⭐ The lifetime risk of developing appendicitis is approximately **7-8%**. 

Appendicitis: Clinical Features - Pain's Pointed March

• Pain Trajectory (Classic):
  • Onset: Dull, periumbilical, colicky (visceral).
  • Migration (📌 "Pointed March"): To Right Iliac Fossa (RIF) within 12-24 hrs.
  • Character: Sharp, constant, localized at McBurney's point.
• Key Associated Symptoms:
  • Anorexia: Often first, highly consistent.
  • Nausea/Vomiting: Typically after pain onset.
  • Fever: Low-grade (< 38.5°C).
• Physical Exam Signs:
  • RIF tenderness, guarding, rebound.
  • Special Tests: Rovsing's, Psoas, Obturator signs positive.

⭐ The sequence of symptoms is crucial: anorexia, then vague abdominal pain, then vomiting, then localization of pain to RIF and fever development (Dieulafoy's triad for sequence: pain, nausea/vomiting, fever).

Appendicitis: Diagnosis & DDx - Case of the Coded Clues

• Clinical Scoring:
  • Alvarado Score (MANTRELS - Migratory RIF pain, Anorexia, Nausea/Vomiting, Tenderness RIF, Rebound, Elevated temp, Leukocytosis, Shift to left): Max 10.
    • Score ≤4: Appendicitis unlikely.
    • Score 5-6: Equivocal → Image.
    • Score ≥7: High probability → Surgery consult.
  • Appendicitis Inflammatory Response (AIR) Score: Max 12. Similar interpretation.
• Lab Tests:
  • ↑WBC (Neutrophilia, left shift).
  • ↑C-Reactive Protein (CRP).
• Imaging:
  • Ultrasound (USG): First-line in children & pregnant women. Appendix diameter >6mm, non-compressible, target sign, appendicolith.
  • Contrast-Enhanced CT (CECT) Abdomen: Gold standard. Dilated appendix >6mm, wall thickening, peri-appendiceal fat stranding, appendicolith.

    ⭐ CECT abdomen has a sensitivity and specificity of >95% for acute appendicitis.

• Differential Diagnosis (DDx):
  • Gastrointestinal: Mesenteric adenitis, Meckel's diverticulitis, Crohn's disease, diverticulitis.
  • Gynecological: Ectopic pregnancy, Pelvic Inflammatory Disease (PID), ovarian torsion/cyst rupture.
  • Urological: Ureteric colic, Pyelonephritis/UTI.
• Diagnostic Pathway:

Appendicitis: Management & Complications - Snip, Stitch, Sidestep

• Initial Steps: NPO, IV fluids, analgesia, broad-spectrum IV antibiotics (e.g., Ceftriaxone + Metronidazole).
• Definitive Management:
  • Appendectomy: Gold standard.
    • Laparoscopic: Preferred; ↓pain, ↓stay, faster recovery.
    • Open: McBurney’s or Lanz incision.
  • Non-Operative Management (NOM): For selected uncomplicated cases with antibiotics. Recurrence risk ~20-30% within 1 year.
• Specific Scenarios:
  • Appendicular Mass: Initial conservative (Ochsner-Sherren regime). Consider interval appendectomy after 6-8 weeks.
  • Appendicular Abscess: Percutaneous drainage + antibiotics. If drainage fails/unavailable → surgery. ⭐ > The most common overall complication following appendectomy is wound infection.

• Key Complications:
  • Perforation (esp. extremes of age)
  • Wound Infection (most common)
  • Intra-abdominal/Pelvic Abscess
  • Stump Appendicitis
  • Adhesive Small Bowel Obstruction (late)
  • Portal Pyemia (septic pylephlebitis - rare)

High‑Yield Points - ⚡ Biggest Takeaways

• McBurney's point tenderness is the most reliable clinical sign.
• Alvarado score (MANTRELS) aids diagnosis; score ≥7 strongly suggests appendicitis.
• USG is initial imaging (children/pregnant); CT scan is most accurate for adults.
• Perforation is the most common serious complication, leading to peritonitis.
• Standard treatment is appendectomy (laparoscopic preferred).
• Obturator and Psoas signs may indicate a retrocecal appendix.
• Key DDx: mesenteric adenitis, ectopic pregnancy, PID, Meckel's diverticulitis.