Acute Appendicitis

Appendicitis refers to inflammation of the appendix. The first appendectomy was completed by Claudius Amyand in 1735 when he operated on an 11-year-old male for a strangulated inguinal hernia and discovered the appendix in the hernial sac. The first intentional appendectomy was performed by Lawson Tait in 1880.

Pathophysiology

• Luminal obstruction from various etiologies
• Luminal obstruction leads to increased intraluminal pressure which decreases venous outflow causing lymphatic congestion resulting in tissue ischemia, inflammation, eventual necrosis, and perforation
• Intraluminal bacteria translocate beyond mucosa and potentiate the inflammatory process causing phlegmon or inflammatory mass

Epidemiology

• Peak incidence 10-30 years old

Presentation

• Periumbilical abdominal pain that migrates to RLQ pain
• Anorexia
• Nausea, vomiting
• Fever, tachycardia
• Rigidity → if present, points towards perforation (usually occurs 24 hours after symptom onset)

• McBurney point: ⅓ distance from right ASIS to umbilicus
• Psoas sign: pain with right hip extension
  • Secondary to peritoneal irritation
  • Specificity 95%, sensitivity 16%
  • Does This Patient Have Appendicitis? (JAMA 1996) 
• Rovsing sign: RLQ pain with palpation of LLQ
  • Due to peritoneal stretch and irritation from contralateral abdominal pressure
  • No study completed to demonstrate sensitivity or specificity
• Obturator sign: RLQ pain with right hip internal rotation
  • No study completed to demonstrate sensitivity or specificity
• Dunphy sign: RLQ pain with coughing

Workup

• Leukocytosis
  • Sensitivity 76%, specificity 52% 
  • Not highly predictive – absence doesn’t exclude appendicitis
• Pregnancy test should be obtained to rule out ectopic pregnancy

• CT w IV contrast
  • Most commonly used; effective and accurate
  • Thickened, inflamed appendix with surrounding “stranding” indicative of inflammation, >7 mm in diameter, mural enhancement or “target sign”
  • Sensitivity 76-100%, specificity 83-100% (Systematic Review: Computed Tomography and Ultrasonography to Detect Acute Appendicitis in Adults and Adolescents) 
• RLQ US
  • May have greater utility in pediatric or pregnant patients to avoid radiation
  • Success of study depends greatly on skill of the sonographer
  • Appendix diameter >6 mm, periappendiceal fat with echogenic enhancement, fluid within RLQ
  • Sensitivity 86%, specificity 81% (Systematic Review: Computed Tomography and Ultrasonography to Detect Acute Appendicitis in Adults and Adolescents) 
• MRI wo contrast
  • Reserved for pregnant patients or second-line imaging when RLQ US is inconclusive
  • Appendix dilation >7 mm, thickening >2 mm, presence of inflammation
  • Cons: higher cost, motion artifact

Treatment

• Nonoperative management
  • CODA trial (2021) compared nonoperative management of appendicitis to appendectomy by looking at >1500 patients
    • Appendicolith is 3x more likely to require appendectomy at 48 hours
    • Nonoperative management can be presented as alternative to appendectomy but patients must understand risk of recurrent symptoms, future hospitalization, and possible failure to diagnose appendiceal neoplasm
    • Concluded that nonoperative management with antibiotics were noninferior to appendectomy. Roughly 30% of patients will undergo appendectomy in 90 days. Patients with appendicolith are higher risk of need for appendectomy compared to patients without appendicolith.
  • APPAC III trial 
• Appendectomy
  • Avoid delay >6 hours if possible
  • Laparoscopic or open

Relevant Information

• Appendix orientation
  • Retrocecal (65%)
  • Pelvic (31%)
  • Subcecal (2.3%)
  • Preileal (1.0%)
  • Retroileal (0.4%)
• Fold of Treves
  • Bloodless fold; no sizable blood vessels
  • Peritoneal structure that extends from the antimesenteric border of the terminal ileum to the base of the appendix, or anterior surface of the mesoappendix, or both
  • Can aid in the recognition of the ileocecal region and base of the appendix

Complications

• Perforation: can lead to sepsis, increased risk with prolonged duration of symptoms; rigidity will be present upon physical exam

Scoring Systems

• No signs or symptoms have been shown to be uniquely predictive of appendicitis, so scoring systems have been developed to help with clinical diagnosis
• Alvarado scoring
  • 8-item clinical and laboratory variables
  • Scoring < 4 useful in excluding appendicitis; higher score lacks specificity
  • Most widely used and acceptable

• Pediatric Appendicitis Score (PAS)
• Appendicitis Inflammatory Response Score (AIRS)

Differential Diagnoses

• Crohn ileitis
• Mesenteric adenitis
• Intussusception
• Meckel diverticulum
• Ectopic pregnancy
• Testicular torsion
• Ovarian torsion
• Kidney stones
• Gastroenteritis
• Pelvic inflammatory disease
• Endometriosis
• Renal colic
• Irritable bowel disease