Lifetime risk: ∼8%Peak incidence: 10-19 years of age

Etiology: Obstruction of appendiceal lumen by- Lymphoid tissue hyperplasia- Fecalith- Less common: foreign bodies, worm infestations, intestinal infections, tumors (eg, carcinoid tumor)

Clinical presentation:- Progressive fever- Anorexia - Nausea, vomiting, diarrhea, and/or constipation- Abdominal pain: → Initially, dull migratory periumbilical pain (due to visceral peritoneum irritation) → After 4-24 hours, sharp RLQ pain (due to parietal peritoneum irritation by a distended and inflamed appendix) with rebound tenderness- Blumberg's sign: rebound tenderness caused upon suddenly ceasing deep palpation of the RLQ- McBurney point tenderness: an area one-third of the distance from the right anterior superior iliac spine to the umbilicus (in the RLQ)- Rovsing's sign: deep palpation of the LLQ causes RLQ referred pain- Psoas sign: RLQ pain with extension of the right leg against resistance (secondary to inflammation of a retrocecal appendix) - Obturator sign: RLQ pain with flexion and internal rotation of the right leg

Diagnostics:- ↑ CRP, mild leukocytosis (11,000-15,000 cells/μL) with left shift- Abdominal ultrasound: non-compressible and enlarged appendix (> 6–8 mm)→ Target sign→ Wall thickening→ Edema surrounding the appendix→ In perforation → intra-abdominal free fluid- Abdominal CT scan

Differential: Pseudoappendicitis (Yersiniosis), Meckel's diverticulum

Therapy:- Bowel rest (keep patient NPO), IV fluid therapy, and observation- Analgesia- Antibiotics with anaerobic and gram negative cover (eg, cefazolin and metronidazole) - Appendectomy

Complications: Gangrenous perforation, abscess