Acute Appendicitis: Surgical Anatomy, Alvarado Score & Management

**1. Surgical Anatomy & Pathogenesis** The vermiform appendix arises from the posteromedial wall of the cecum, approximately 2.5 cm inferior to the ileocecal valve, where the three taeniae coli converge. The most common anatomical position is **Retrocecal** (65–70%), followed by **Pelvic** (30%). * **Primary Pathogenetic Event**: Luminal obstruction. In young adults, obstruction is caused by **lymphoid follicular hyperplasia** (often post-viral); in older adults, by a **fecolith** (appendicolith), foreign body, or carcinoid tumor. * **Progression**: Continued mucus secretion behind the obstruction increases intraluminal pressure, compromising venous drainage, triggering bacterial invasion (*E. coli*, *Bacteroides fragilis*), ischemic mucosal necrosis, gangrene, and eventual perforation. **2. Classical Symptom Progression (Murphy's Triad)** Murphy's classical chronological sequence of symptoms occurs in over 80% of patients: 1. *Pain*: Begins as dull, poorly localized periumbilical visceral pain (referred along the T10 dermatome via the sympathetic lesser splanchnic nerves). 2. *Anorexia, Nausea, and Vomiting*: Anorexia is so consistent that hunger should prompt reconsideration of the diagnosis. 3. *Somatic Pain Shift*: Over 6 to 12 hours, transmural inflammation contacts the parietal peritoneum, causing the pain to shift and localize sharply to the **Right Iliac Fossa (RIF)**. **3. Physical Signs on Examination** * **McBurney's Point Tenderness**: Maximal tenderness located at the junction of the lateral 1/3 and medial 2/3 of a line connecting the anterior superior iliac spine (ASIS) to the umbilicus. * **Rovsing's Sign**: Palpation of the left iliac fossa elicits pain in the right iliac fossa (due to retrograde displacement of colonic gas stretching the inflamed cecum/appendix). * **Psoas Sign**: Passive hyperextension of the right hip with patient in left lateral position elicits pain, indicating an inflamed retrocecal appendix irritating the iliopsoas muscle. * **Obturator Sign**: Pain elicited on passive internal rotation of the flexed right hip, indicating a pelvic appendix irritating the obturator internus muscle. * **Blumberg's Sign**: Rebound tenderness indicating localized parietal peritonitis. **4. 🔬 Diagnostic Scoring & Imaging** * **Alvarado (MANTRELS) Score (Total = 10 Points)**: - *Symptoms*: **M**igration of pain (1), **A**norexia (1), **N**ausea/Vomiting (1). - *Signs*: **T**enderness in RIF (2), **R**ebound tenderness (1), **E**levated temperature $\ge$ 37.3°C (1). - *Lab*: **L**eukocytosis >10,000/mcL (2), **S**hift to left of neutrophils (1). - *Score $\ge$ 7*: High probability; strongly indicates need for emergency surgery. * **Ultrasonography**: Graded-compression US shows a non-compressible, blind-ending, aperistaltic tubular structure with an outer diameter **>6 mm**, "target sign" on transverse view. * **Contrast-Enhanced CT (CECT) of Abdomen**: Most sensitive (>95%) and specific imaging modality; demonstrates enlarged appendix (>6 mm), appendiceal wall thickening, periappendiceal fat stranding, and appendicoliths. **5. Definitive Surgical Management** * **Laparoscopic Appendectomy**: Gold standard. Advantages: reduced postoperative pain, lower wound infection rates, shorter hospital stay, and enables complete diagnostic peritoneal exploration. * **Open Appendectomy**: Performed via a transverse skin crease incision (Lanz) or gridiron muscle-splitting incision (McBurney's). * **Antibiotic Prophylaxis**: Preoperative broad-spectrum IV Ceftriaxone (or Cefotaxime) plus Metronidazole administered within 60 minutes prior to incision. **6. 📖 Standard Textbook Reference** * *Bailey & Love's Short Practice of Surgery*, 28th Ed., Ch. 73: The Vermiform Appendix, pp. 1312–1326. * *Sabiston Textbook of Surgery*, 21st Ed., Ch. 51: The Appendix, pp. 1295–1310.