Fact-sheet: Appendicitis
Updated on 04/09/2026 at 12:25 PM
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Definition
Acute inflammation of the vermiform appendix of the cecum promoted by luminal obstruction, which may result from an appendicolith (25% of cases), lymphoid hyperplasia, a foreign body, or more rarely a cecoappendiceal tumor or parasites.
4 stages: catarrhal, suppurative, gangrenous, perforated.
Complications: appendiceal phlegmon, acute peritonitis, appendiceal perforation, and periappendiceal abscess.
Several topographic forms: classic, retrocecal, subhepatic, pelvic, mesoceliac.
Clinical features
Peak incidence: 15-25 years.
Classic presentation: Epigastric pain migrating to the RLQ within a few hours.
Mild fever (38-38.5°C).
Guarding at McBurney's point +/- psoas sign.
Laboratory findings
Usually mild neutrophilic leukocytosis.
Ultrasound
Blind-ending tubular structure (appendix) distended to ≥7mm in diameter, non-compressible, with wall thickening.
Fluid collection frequently associated in the pouch of Douglas.
Pain on probe compression: sonographic McBurney's sign.
Echogenic appendicolith with posterior acoustic shadowing.
Doppler hyperemia of the appendiceal wall.
Inflammatory hyperechogenicity of the periappendiceal fat.
CT
Indicated when ultrasound is inconclusive.
Reference examination, to be performed with contrast injection
Swollen appendix with wall enhancement, particularly of the inflamed mucosa.
Transmural necrosis: absence of enhancement.
Periappendiceal fat stranding.
Appendicolith
Search for periappendiceal abscess, phlegmon, or pneumoperitoneum bubble indicating perforation.
MRI
Alternative in children and pregnant women when ultrasound is inconclusive.
Differential diagnosis
- Mesenteric lymphadenitis
- Ectopic pregnancy
- Crohn disease
- Cecal diverticulitis
- Torsion of ovary
- Acute salpingitis
- Mucocele of appendix and other appendiceal tumors
- Cecal carcinoma
- Cystic fibrosis