Special Surgery 25. Acute Appendicitis: Symptomatics, Diagnostics, Treatments

I. Definition, Etiology and Pathogenesis

Definition

• Acute appendicitis: acute inflammation of the vermiform appendix
• Common cause of acute surgical abdomen

Etiology

• Main mechanism: appendiceal lumen obstruction
• Causes: lymphoid hyperplasia, fecalith/appendicolith, foreign body, parasite infection, neoplasm

Pathogenesis

1. Appendiceal obstruction → mucosal secretion stasis
2. Stasis → bacterial overgrowth → local inflammation
3. Rising intraluminal pressure → venous congestion + wall edema
4. Progressive pressure → arterial ischemia → transmural infection
5. Gangrenous appendicitis +/- perforation → abscess/phlegmon or diffuse peritonitis

II. Clinical Features and Complications

Typical Clinical Features

• Abdominal pain: starts periumbilically/centrally → localizes to RLQ
• McBurney point: junction of lateral and middle third from right ASIS to umbilicus
• Lanz point: right third of line between both ASIS
• Pain worsens with coughing, walking, movement or transport
• Anorexia, malaise, low-grade fever
• Nausea/vomiting usually after pain starts
• Constipation or diarrhea; urinary symptoms possible with pelvic appendix

Physical Signs

• McBurney point tenderness and localized RLQ guarding
• Blumberg sign / rebound tenderness: pain when abdominal compression is suddenly released
• Rovsing sign: LLQ palpation worsens pain in RLQ
• Psoas sign: RLQ pain with passive right hip extension or resisted right hip flexion → retrocecal appendix
• Obturator sign: RLQ/hypogastric pain with internal rotation of flexed right hip and knee → pelvic appendix
• Rosenstein / Sitkovskiy sign: increased right iliac/RLQ pain when patient lies on left side
• Diffuse rigidity, severe rebound, sepsis → perforation / diffuse peritonitis

Complications

• Perforation → localized or diffuse peritonitis
• Appendiceal abscess or phlegmon
• Sepsis and septic shock
• Adhesive small bowel obstruction later

III. Diagnosis and Differential Diagnosis

Clinical Assessment and Labs

• Diagnosis: history + physical examination + labs + selective imaging
• CBC: leukocytosis with neutrophilia; CRP increased
• Pregnancy test: all women of reproductive age
• Urinalysis: mild pyuria/hematuria possible if appendix is near ureter/bladder

Imaging

• Ultrasound: first-line in children and pregnant women

• Findings: non-compressible tubular structure in RLQ, diameter >6 mm, appendicolith, periappendiceal fluid/abscess
• Limitation: operator-dependent

• CT abdomen/pelvis with IV contrast: most accurate common adult test if uncertain or complicated disease suspected

• Findings: dilated appendix >6 mm, wall thickening, fat stranding, appendicolith, abscess/phlegmon, free air/fluid

Classification and Differential Diagnosis

• Uncomplicated appendicitis: inflamed appendix without perforation, abscess, phlegmon or diffuse peritonitis
• Complicated appendicitis: gangrene, perforation, abscess, phlegmon or diffuse peritonitis
• GI: gastroenteritis, Meckel diverticulitis, cecal/sigmoid diverticulitis, Crohn/terminal ileitis, mesenteric lymphadenitis, colon cancer
• Urological/retroperitoneal: renal colic, UTI/pyelonephritis, pancreatitis
• Gynecological: ectopic pregnancy, ovarian torsion/cyst, PID, menstrual pain

IV. Treatment

Initial Management

• Surgical assessment, NPO, IV access, fluids if dehydrated/septic, analgesia/antiemetics
• Broad-spectrum antibiotics covering Gram-negative and anaerobic flora if appendicitis likely and operation or non-operative treatment planned

Surgical Treatment: Appendectomy

• Standard definitive treatment
• Laparoscopic appendectomy: preferred in most patients
• Open appendectomy: selected cases, resource-limited setting, or laparoscopy unavailable/contraindicated
• Open incisions: McBurney/Gridiron or Lanz
• Complicated appendicitis/peritonitis: antibiotics + urgent source control; postoperative antibiotics if complicated

Non-Operative Treatment

• Selected stable uncomplicated appendicitis: NPO, IV antibiotics, observation
• Best candidates: no appendicolith, no perforation, no abscess/phlegmon, no peritonitis, reliable follow-up
• Counseling: early failure and recurrence risk; appendicolith increases failure/perforation risk

Appendiceal Abscess / Phlegmon

• Stable localized abscess/phlegmon: IV antibiotics +/- image-guided percutaneous drainage if drainable
• Emergency operation if diffuse peritonitis, uncontrolled sepsis, free perforation or failed conservative/drainage treatment
• Older adults / recurrent symptoms: follow-up to exclude cecal or appendiceal tumor